Sezonowe zaburzenie afektywne – Patofizjologia i mechanizm

Sezonowe zaburzenie afektywne
Patofizjologia i mechanizm

Sezonowe zaburzenia afektywne (SAD) to podtyp depresji charakteryzujący się nawracającymi epizodami depresyjnymi w określonych porach roku, najczęściej jesienią i zimą, z ustępowaniem objawów wiosną lub latem. Etiologia SAD jest wieloczynnikowa, obejmująca zaburzenia rytmu dobowego, zmniejszoną wrażliwość siatkówki na światło, dysfunkcję układu serotoninergicznego, zmiany w wydzielaniu melatoniny oraz czynniki genetyczne, w tym mutacje w genie PER3 i potencjalną rolę genu ZBTB20. Patofizjologia obejmuje opóźnienie fazy rytmu dobowego, co tłumaczy skuteczność porannej fototerapii, oraz zaburzenia w metabolizmie neuroprzekaźników, w tym zwiększoną aktywność monoaminooksydazy A (MAO-A) w okresie zimowym. SAD dotyka do 6% dorosłej populacji, a jego częstość wzrasta wraz z odległością od równika, co podkreśla rolę ekspozycji na światło słoneczne w patogenezie.

Patogeneza sezonowych zaburzeń afektywnych (SAD)

Sezonowe zaburzenia afektywne (SAD) stanowią podtyp zaburzeń depresyjnych, charakteryzujący się nawracającymi epizodami depresyjnymi, które pojawiają się w określonej porze roku (najczęściej jesienią i zimą) i ustępują wraz z nadejściem innej pory (zwykle wiosny lub lata). Zaburzenie to dotyka do 6% dorosłej populacji, a jego częstość występowania wzrasta wraz z odległością od równika, co sugeruje związek z ekspozycją na światło słoneczne.¹²³

Etiologia SAD jest złożona i wciąż nie w pełni poznana. Uważa się, że w rozwoju zaburzenia kluczową rolę odgrywa kombinacja czynników fizjologicznych, psychologicznych, genetycznych i środowiskowych. Wśród głównych mechanizmów patogenetycznych wymienia się: zaburzenia rytmu dobowego, zmniejszoną wrażliwość siatkówki na światło, zmiany w uwalnianiu neuroprzekaźników (serotoniny, melatoniny, dopaminy) oraz czynniki genetyczne.⁴¹

Zaburzenia rytmu dobowego

Jednym z głównych proponowanych mechanizmów patofizjologicznych SAD są zaburzenia rytmu dobowego (cyklu okołodobowego). Zredukowany poziom światła słonecznego w miesiącach jesienno-zimowych może zaburzać wewnętrzny zegar biologiczny organizmu i prowadzić do rozwoju objawów depresyjnych.⁵⁶

W literaturze występują dwie główne teorie wyjaśniające wpływ rytmu dobowego na rozwój SAD:

Hipoteza fotoperiodu – sugeruje, że krótsze dni i dłuższe noce w okresie zimowym mogą wywoływać depresję u osób podatnych poprzez przedłużone wydzielanie melatoniny. Ssaki, w tym ludzie, wykorzystują zmiany długości dnia do wykrywania zmian sezonowych, co wpływa na zachowania sezonowe głównie poprzez czas trwania nocnego wydzielania melatoniny.⁷⁸
Hipoteza przesunięcia fazowego – wskazuje, że opóźnienie fazy rytmu dobowego względem cyklu snu i czuwania może prowadzić do objawów SAD. Badania sugerują, że objawy fizjologiczne i psychologiczne u pacjentów z SAD są wynikiem przesunięcia fazy rytmu okołodobowego w miesiącach zimowych, gdy naturalne rytmy dobowe pacjentów, modulowane przez melatoninę, są opóźnione w stosunku do rzeczywistego cyklu snu i czuwania.⁷⁹¹⁰

Najczęściej SAD wiąże się z opóźnieniem fazy rytmu dobowego. Wyjaśnia to skuteczność porannej fototerapii, która może pomóc zresetować wewnętrzny zegar biologiczny do wcześniejszej fazy zsynchronizowanej z cyklem dzień-noc, co prowadzi do szybkiej poprawy stanu klinicznego.⁴¹¹

Zmiany w poziomie neuroprzekaźników

Serotonina

Nieprawidłowe funkcjonowanie układu serotoninergicznego w ośrodkowym układzie nerwowym jest istotnym czynnikiem w patogenezie SAD. Zmniejszona ekspozycja na światło słoneczne może prowadzić do spadku poziomu serotoniny, neuroprzekaźnika odpowiedzialnego za regulację nastroju.⁵¹²¹³

Badania wykazały zmniejszoną aktywność serotoninergiczną i zmienione poziomy białka transportera serotoniny u osób cierpiących na SAD. Eksperymenty z deplecją tryptofanu (prekursora serotoniny) potwierdziły rolę serotoniny w patogenezie, ponieważ wywoływały objawy depresyjne u pacjentów z SAD, którzy wcześniej odpowiedzieli na terapię jasnym światłem.¹⁴

Osoby z SAD mają wyższe poziomy transportera serotoniny (SERT) w okresie zimowym, co prowadzi do niższych poziomów serotoniny. Badacze uważają, że nieprawidłowa regulacja serotoniny może przyczyniać się do rozwoju sezonowych zaburzeń afektywnych, szczególnie gdy poziom światła słonecznego jest niższy.¹⁵¹⁶

Melatonina

Melatonina jest hormonem wydzielanym przez szyszynkę w warunkach zmniejszonego oświetlenia i ciemności. Zmiany sezonowe mogą zaburzać równowagę poziomu melatoniny w organizmie, co wpływa na wzorce snu i nastrój.⁵²

Jasne światło działa jako zeitgeber (zewnętrzny wskaźnik czasu), który wpływa na uwalnianie melatoniny. Istnieje odwrotna zależność między intensywnością ekspozycji na światło a ilością wydzielanej melatoniny. Ciemność stymuluje wydzielanie melatoniny przez szyszynkę w mózgu. Gdy dni są krótsze i ciemniejsze, produkuje się więcej melatoniny, co może prowadzić do hipersomnii (zwiększonej długości snu lub nadmiernej senności w ciągu dnia).⁴¹⁷¹⁸

Badania grupy dr. Wehra sugerują, że pacjenci z SAD mogą być bliżsi swoim korzeniom ssaczym niż inni; podczas gdy u zdrowych ochotników nie zaobserwowano sezonowych zmian, nocne wydzielanie melatoniny u pacjentów z SAD było dłuższe zimą niż latem.⁸

Inne neuroprzekaźniki i enzymy

SAD wiąże się również z innymi neuroprzekaźnikami, w tym dopaminą, norepinefryną i glutaminianem, chociaż dokładna patofizjologia nie jest jasna.¹

Istotną rolę może odgrywać także monoaminooksydaza A (MAO-A), enzym odpowiedzialny za rozkład neuroprzekaźników. Badania z wykorzystaniem pozytonowej tomografii emisyjnej (PET) wykazały, że u osób zdrowych poziom MAO-A w mózgu zmniejsza się od jesieni/zimy do wiosny/lata, podczas gdy u pacjentów z SAD ta sezonowa dynamika jest zaburzona. Ponadto, fototerapia jasnym światłem (BLT) prowadzi do znaczącego zmniejszenia poziomu MAO-A, co teoretycznie może skutkować zmniejszeniem degradacji serotoniny, prowadząc do wyższych poziomów serotoniny i ostatecznie działania przeciwdepresyjnego.¹⁹²⁰

Co ciekawe, badania wykazały, że osoby z sezonowymi zaburzeniami afektywnymi nie mają sezonowego rytmu monoaminooksydazy A. Ta nieprawidłowość może powodować nadmierny rozkład serotoniny w okresie zimowym, przyczyniając się do rozwoju sezonowych zaburzeń afektywnych.²¹

Czynniki genetyczne

Badania rodzinne i bliźniąt wykazały komponent genetyczny w rozwoju SAD. Chociaż naukowcy nie zidentyfikowali konkretnej mutacji genetycznej odpowiedzialnej za SAD, wyniki badań wskazują na rolę kilku genów w podatności na to zaburzenie.²²²¹

W badaniu asocjacyjnym całego genomu (GWAS) zidentyfikowano gen ZBTB20 jako potencjalny gen podatności na SAD. ZBTB20 koduje represor transkrypcyjny, który odgrywa kluczową rolę w neurogenezie. Chociaż nie osiągnięto istotności statystycznej na poziomie całego genomu, zbieżność dowodów genetycznych, genomicznych i biologicznych sugeruje, że szlaki regulowane przez ZBTB20 mogą być istotne w etiologii SAD.²²²³

Innym obiecującym odkryciem jest identyfikacja mutacji ludzkiego genu PER3 (należącego do rodziny genów okołodobowych Period), która wydaje się przyczyniać zarówno do nietypowych wzorców snu, jak i zwiększonej częstości występowania sezonowej depresji. To pierwszy ludzki gen bezpośrednio powiązany z sezonowymi zaburzeniami afektywnymi i pierwszy wyraźny znak mechanizmu, który mógłby łączyć sen z zaburzeniami nastroju.²⁴²⁵

Badania na myszach z wprowadzoną zmutowaną formą genu PER3 wykazały, że behawioralnie przypominały one ludzi z sezonowymi zaburzeniami afektywnymi, rozwijając objawy podobne do depresji, gdy były narażone na krótkie 4-godzinne dni i 20-godzinne noce.²⁶²⁷

Wyniki badań nad sezonowością i aktywnością genów wykazały zmiany w ekspresji genów w różnych porach roku, przy czym niektóre geny są bardziej aktywne latem lub zimą.¹⁴

Inne czynniki patogenetyczne

Niedobór witaminy D

Zaproponowano, że niski poziom witaminy D może odgrywać rolę w rozwoju SAD. U osób z sezonowymi zaburzeniami afektywnymi stwierdzono niedobór witaminy D, co może być spowodowane zmniejszoną ekspozycją na światło słoneczne i/lub niskim spożyciem pokarmów bogatych w witaminę D. Witamina D wpływa na aktywność serotoniny w mózgu. Jednak badania nie wykazały jednoznacznie, że suplementacja witaminą D może zapobiegać lub łagodzić objawy SAD.⁴²⁸¹⁷²⁹

Zmieniona wrażliwość siatkówki

Niektóre badania sugerują, że osoby z SAD mogą mieć problem z wrażliwością siatkówki na światło. Jedno z badań zidentyfikowało związek między SAD a mutacją, która zmniejsza wrażliwość oka na światło.²⁸²¹³⁰

Badania wskazują, że to mechanizm oczny odgrywa kluczową rolę w absorpcji terapii światłem. Sztuczna fototerapia jasnym światłem wnika do oka poprzez mechanizm receptorowy siatkówki. Bezwzględnie potrzebujemy tego sygnału ocznego rano, aby pozostać w synchronizacji z naszym zewnętrznym światem.³¹¹⁸³²

Zaburzenia cyklu temperatury ciała

Istnieją dowody, że SAD może być związane z odchyleniami w dziennych cyklach podstawowej temperatury ciała i hormonów metabolicznych (uwalniających energię), takich jak kortyzol.²⁸

Mechanizmy działania terapii w SAD

Fototerapia

Fototerapia jest jedną z najbardziej skutecznych metod leczenia SAD, z efektywnością sięgającą 85% przypadków. Terapia światłem ma na celu zastąpienie brakującego światła dziennego w okresie zimowym poprzez ekspozycję na jasne światło, które naśladuje naturalne światło zewnętrzne.³³²⁸

Mechanizm działania fototerapii nie został jednoznacznie ustalony, ale proponowane są różne hipotezy:

Przesunięcie fazy rytmu dobowego – istnieją dowody, że wielu pacjentów z SAD ma opóźnienie w rytmie dobowym, a jasna terapia światłem koryguje te opóźnienia.³⁴
Odwrócenie zwiększonego poziomu melatoniny, zmniejszonej transmisji 5-hydroksytryptaminy i dopaminy.³⁵
Regulacja wydzielania melatoniny – światło jest zeitgeberem (zewnętrznym wskaźnikiem czasu), który wpływa na uwalnianie melatoniny.⁴
Zwiększenie poziomu serotoniny – ekspozycja na światło może zwiększać poziom serotoniny w mózgu.³³

Metaanaliza badań nad fototerapią wykazała, że dla terapii światłem o średniej intensywności, kombinacja terapii rano i wieczorem dawała najlepszy efekt terapeutyczny, a działanie przeciwdepresyjne terapii światłem rano i wieczorem było lepsze niż pojedynczy impuls światła podawany o innych porach dnia. Ponadto, dane wykazały, że działanie przeciwdepresyjne pojedynczego impulsu światła było podobne dla światła porannego, południowego i wieczornego. Wyniki te potwierdziły hipotezę liczby fotonów i obaliły proponowane modele fotoperiodu, melatoniny i przesunięcia fazowego w SAD.³⁶

Farmakoterapia

Chociaż dane dotyczące leków psychoaktywnych i ich stosowania w leczeniu sezonowych zaburzeń afektywnych są ograniczone, inhibitory wychwytu zwrotnego serotoniny (SSRI) fluoksetyna i sertralina były najbardziej badane i wydają się skuteczne.³⁷

Według Amerykańskiego Towarzystwa Psychiatrycznego, SAD (duże zaburzenie depresyjne z wzorcem sezonowym) można leczyć całym zakresem leków dostępnych do leczenia dużego zaburzenia depresyjnego.³⁷

Leki przeciwdepresyjne działają poprzez modyfikację produkcji lub wykorzystania przez mózg określonych neuroprzekaźników i chemikaliów, które odgrywają kluczową rolę w regulacji nastroju i zarządzaniu reakcjami na stres.³⁸

Mechanizmy działania różnych grup leków stosowanych w SAD:

Selektywne inhibitory wychwytu zwrotnego serotoniny (SSRI) – działają poprzez hamowanie wychwytu serotoniny w ośrodkowym układzie nerwowym, co zwiększa jej poziom w przestrzeni synaptycznej. Leki te obejmują fluoksetynę, paroksetynę i sertralinę.³⁷³⁹
Inhibitory wychwytu zwrotnego serotoniny i noradrenaliny (SNRI) – hamują wychwyt zwrotny zarówno serotoniny, jak i noradrenaliny. Przykładem jest duloksetyna, której działanie przeciwdepresyjne teoretycznie wynika z serotoninergicznego i noradrenergicznego wzmocnienia w OUN.³⁹
Inhibitory wychwytu zwrotnego dopaminy/noradrenaliny – bupropion (Wellbutrin) działa poprzez regulację poziomu norepinefryny i dopaminy w mózgu. Jest zatwierdzony przez FDA do zapobiegania SAD, chociaż dowody na jego skuteczność w leczeniu SAD są bardziej ograniczone.³⁷⁴⁰
Inhibitory monoaminooksydazy (IMAO) – leki takie jak tranylcypromina i fenelzyna hamują enzym monoaminooksydazę, który jest odpowiedzialny za rozkład neuroprzekaźników, zwiększając tym samym endogenne stężenie epinefryny, norepinefryny i serotoniny.³⁹

Chociaż istnieją pewne dowody potwierdzające stosowanie leków przeciwdepresyjnych drugiej generacji w SAD, przegląd Cochrane wykazał niewystarczające dowody, aby wyciągnąć ogólne wnioski dotyczące ich skuteczności.²⁹

Terapia poznawczo-behawioralna

Terapia poznawczo-behawioralna (CBT) jest skuteczną metodą leczenia SAD. Pomaga ona pacjentom rozwijać strategie radzenia sobie z objawami i identyfikować negatywne wzorce myślenia związane z zaburzeniem.⁴¹²⁹

Jak wyjaśnia jeden z badaczy: „Nie kwestionuję, że istnieje silny komponent fizjologiczny w SAD i jest on z pewnością związany z cyklem światło-ciemność, ale twierdzę, że osoba ma pewną kontrolę nad tym, jak reaguje i radzi sobie z tym.”¹⁰

Inne metody leczenia

Inne metody leczenia stosowane w SAD to:

Suplementacja melatoniny – badano jako opcję leczenia SAD.²⁹
Suplementacja witaminy D – ze względu na jej rolę w regulacji serotoniny w mózgu.²⁹
Codzienne spacery na zewnątrz – nawet w pochmurne dni mogą znacznie poprawić objawy SAD, szczególnie w połączeniu z fototerapią. Badanie wykazało, że pacjenci, którzy codziennie rano spacerowali przez 60 minut w połączeniu z fototerapią, mieli większą poprawę objawów niż ci, którzy otrzymywali tylko fototerapię.²⁹
Regularne ćwiczenia fizyczne – badania wykazały, że ćwiczenia przez 20 minut co najmniej trzy dni w tygodniu mają podobną skuteczność jak przyjmowanie leków przeciwdepresyjnych.⁴²

Podsumowanie wiedzy o patogenezie SAD

Etiologia i patofizjologia sezonowych zaburzeń afektywnych jest złożona i obejmuje interakcję wielu czynników biologicznych, genetycznych i środowiskowych. Główne mechanizmy leżące u podstaw SAD to zaburzenia rytmu dobowego, zmiany w poziomie neuroprzekaźników (szczególnie serotoniny i melatoniny), czynniki genetyczne oraz zmniejszona wrażliwość siatkówki na światło.⁴³

Chociaż dokładny mechanizm patofizjologiczny nie jest jeszcze w pełni poznany, ostatnie postępy w określaniu molekularnych mechanizmów ludzkiego zegara dobowego i fototransdukcji światła w siatkówce zapewnią ważne nowe kierunki przyszłych badań nad etiologią i patofizjologią SAD.⁴³

Warto zauważyć, że sprzeczne wyniki niektórych badań mogą wskazywać, że SAD jest biologicznie heterogennym stanem, a hipoteza podwójnej podatności, która konceptualizuje sezonowość jako konstrukt wymiarowy, może mieć wartość heurystyczną w przyszłych badaniach.⁴³

Zrozumienie mechanizmów patogenetycznych SAD ma kluczowe znaczenie dla opracowywania skutecznych metod leczenia, z których najważniejsze to fototerapia, farmakoterapia (głównie SSRI i bupropion) oraz terapia poznawczo-behawioralna.²⁸⁴⁴⁴⁵

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Materiały źródłowe

#1 Seasonal Affective Disorder – StatPearls – NCBI Bookshelf
https://www.ncbi.nlm.nih.gov/books/NBK568745/
Seasonal affective disorder (SAD) poses a significant challenge to mental health, affecting mood and overall well-being, especially during months with reduced daylight hours. Recognized as a subtype of major depressive disorder and bipolar disorder, SAD typically presents with major depressive episodes in the fall or winter and alleviates by spring or summer. […] Notably, SAD’s prevalence increases with distance from the equator, suggesting a link to environmental light exposure. […] The etiology of SAD involves complex factors like circadian rhythm disruptions, changes in melatonin and serotonin levels, and photoperiod sensitivity. […] SAD is believed to have a multifaceted etiology, with various hypotheses suggesting that sunlight deficiency and hormonal changes play significant roles. SAD is associated with a seasonal pattern, typically starting in the fall and continuing into the winter months when daylight hours are shorter. The condition is linked to neurotransmitters like dopamine, norepinephrine, and glutamate, although the exact pathophysiology is unclear.
#2 Seasonal affective disorder – Wikipedia
https://en.wikipedia.org/wiki/Seasonal_affective_disorder
Seasonal affective disorder (SAD) is a mood disorder subset in which people who typically have normal mental health throughout most of the year exhibit depressive symptoms at the same time each year. […] It is commonly, but not always, associated with the reductions or increases in total daily sunlight hours that occur during the winter or summer. […] Various proximate causes have been proposed. One possibility is that SAD is related to a lack of serotonin, and serotonin polymorphisms could play a role in SAD, although this has been disputed. […] Another theory is that the cause may be related to melatonin, which is produced in dim light and darkness by the pineal gland, since there are direct connections, via the retinohypothalamic tract and the suprachiasmatic nucleus, between the retina and the pineal gland.
#3 Management of seasonal affective disorder | The BMJ
https://www.bmj.com/content/340/bmj.c2135
Low mood associated with a certain season (usually winter) is very common. For example, in the UK, up to 6% of adults have recurrent major depressive episodes with seasonal pattern, commonly known as seasonal affective disorder (SAD). […] Evidence suggests that SAD has a genetic element, with genes affecting serotonin metabolism (which has a seasonal pattern) being implicated in seasonal mood variations.
#4 Seasonal Affective Disorder (SAD): Background, Pathophysiology, Epidemiology
https://emedicine.medscape.com/article/2500054-overview
Seasonal affective disorder (SAD) is a syndrome typically used to describe a recurrent, seasonal pattern of depressive episodes. […] SAD is a relatively common syndrome with significant effects on mood and psychosocial functioning. […] The etiology of SAD is not completely understood. A combination of physiologic, psychologic, genetic and environmental factors likely play a role. […] Circadian phase delay, retinal subsensitivity to light, altered neurotransmitter release (e.g., serotonin, melatonin, dopamine), hypovitaminosis D and genetic variations in clock, monoamine and retinal photopigment genes have all been proposed mechanisms underlying the etiology of SAD. […] Given the change in photoperiod length (longer nights and shorter days) and that bright light therapy (BLT) has an antidepressant effect, circadian rhythms have been hypothesized to contribute to the onset of SAD. […] Most commonly, SAD is associated with a phase-delay in circadian rhythms. […] Bright light is a zeitgeber (external time cue) that affects melatonin release. […] It has been proposed that low vitamin D may play a role in the development of SAD.
#5 Seasonal affective disorder (SAD) – Symptoms & causes – Mayo Clinic
https://www.mayoclinic.org/diseases-conditions/seasonal-affective-disorder/symptoms-causes/syc-20364651
Seasonal affective disorder (SAD) is a type of depression that’s related to changes in seasons seasonal affective disorder (SAD) begins and ends at about the same times every year. […] The specific cause of seasonal affective disorder remains unknown. Some factors that may come into play include: […] The reduced level of sunlight in fall and winter may cause winter-onset SAD. This decrease in sunlight may disrupt your body’s internal clock and lead to feelings of depression. […] A drop in serotonin, a brain chemical (neurotransmitter) that affects mood, might play a role in SAD. Reduced sunlight can cause a drop in serotonin that may trigger depression. […] The change in season can disrupt the balance of the body’s level of melatonin, which plays a role in sleep patterns and mood.
#6 Overview – Seasonal affective disorder (SAD) – NHS
https://www.nhs.uk/mental-health/conditions/seasonal-affective-disorder-sad/overview/
The exact cause of SAD is not fully understood, but it’s often linked to reduced exposure to sunlight during the shorter autumn and winter days. […] The main theory is that a lack of sunlight might stop a part of the brain called the hypothalamus working properly, which may affect the: […] production of melatonin melatonin is a hormone that makes you feel sleepy; in people with SAD, the body may produce it in higher than normal levels […] production of serotonin serotonin is a hormone that affects your mood, appetite and sleep; a lack of sunlight may lead to lower serotonin levels, which is linked to feelings of depression […] body’s internal clock (circadian rhythm) your body uses sunlight to time various important functions, such as when you wake up, so lower light levels during the winter may disrupt your body clock and lead to symptoms of SAD. […] It’s also possible that some people are more vulnerable to SAD as a result of their genes, as some cases appear to run in families.
#7 Seasonal Affective Disorder – StatPearls – NCBI Bookshelf
https://www.ncbi.nlm.nih.gov/books/NBK568745/
While the underlying causes of SAD remain unclear, several hypotheses are proposed. These include disturbances in circadian rhythms, reduced retinal sensitivity, genetic factors, and dysregulation of neurotransmitters such as serotonin. […] One model suggests 2 contributing factors: a seasonal element and a depressive component, each driven by different mechanisms. For instance, seasonal changes in circadian rhythms, influenced by the length of daylight, may contribute to symptoms of SAD. Two main theories based on circadian rhythms have been proposed: the photoperiod hypothesis, which suggests that shorter daylight hours in winter may trigger depression in vulnerable individuals due to prolonged melatonin secretion, and the phase shift hypothesis, which proposes that misalignment between circadian rhythms and sleep may lead to symptoms of SAD.
#8 Seasonal affective disorder | The British Journal of Psychiatry | Cambridge Core
https://www.cambridge.org/core/journals/the-british-journal-of-psychiatry/article/seasonal-affective-disorder/06A6698BA5D4D55593F01B028960D41F
The pathophysiology of SAD is complex and intriguing. […] Mammals use changes in day length to detect seasonal changes, which in turn regulate seasonal behaviours, largely through the duration of nocturnal melatonin secretion. […] A recent paper by Dr Wehr’s group suggests that SAD sufferers may be closer to their mammalian roots than others; while healthy volunteers showed no seasonal change, the nocturnal melatonin secretion of patients with SAD was longer in winter than in summer.
#9 Winter makes me SAD: The biological story behind seasonal affective disorder and its potential treatments – ScIU
https://blogs.iu.edu/sciu/2019/03/05/winter-makes-me-sad/
To answer these questions, we need to look deeper into the physiological mechanisms that underlie SAD. More specifically, we must examine the processes that are responsible for maintaining the bodys circadian, or daily, rhythms. […] Studies suggest that the physiological and psychological symptoms displayed by SAD patients are the result of circadian phase shifting during the winter months, in which patients natural circadian rhythms, which are modulated by melatonin, are delayed relative to their actual sleep/wake cycle. […] While a few different theories have been proposed to explain the psychological symptoms associated with SAD, one hypothesis in particular, the phase-shift hypothesis, has garnered the most support from scientists. The phase-shift hypothesis suggests that SAD patients have delayed circadian rhythms relative to their sleep/wake cycle.
#10 Winter blues and the story of SAD | Wellcome Collection
https://wellcomecollection.org/stories/winter-blues-and-the-story-of-sad
Another theory is that people with SAD are less responsive to light, so that once light levels fall below a certain threshold particularly if sufferers are spending a lot of time indoors they struggle to synchronise their circadian clocks with the outside world. […] However, the leading theory is the phase-shift hypothesis: the idea that later sunrises in winter delay our internal rhythms so that theyâre no longer in tune with when we go to sleep and wake up. […] If this pattern were to become misaligned with the actual time of day, then those lows in mood might occur during the daytime instead. […] If our bodies were still in night mode when we woke up, we might also feel more tired and sluggish another common symptom of SAD. […] I dont argue that theres a strong physiological component to SAD, and its certainly tied to the light-dark cycle, she says. But I do argue that the person has some control over how they respond to and cope with that.
#11
https://www.healio.com/news/optometry/20120225/ocular-mechanism-key-to-light-therapy-for-seasonal-affective-disorder
The specific physiological event that corrects this problem is exposure to adequately timed early morning light. […] When light therapy resets the internal clock to an earlier phase synchronized with the day-night cycle, extremely rapid reversals in clinical depression may result. […] Artificial bright light therapy enters the eye through a retinal receptor mechanism, Dr. Terman said. […] The amount of light at night determines how much melatonin is released from the pineal gland and secreted into the bloodstream, Dr. Bergin said. An inverse relationship exists between the intensity of light exposure and the amount of melatonin secreted. […] Therefore, he said, people who are vulnerable to depression related to light deprivation have a critical need for regular light exposure to allay oversleeping and depression.
#12
https://healthmatch.io/seasonal-affective-disorder/reverse-seasonal-affective-disorder
SAD is a depressive mood disorder brought on by the changing seasons. Typically, this presents during the winter months when the day length decreases, reducing our exposure to sunlight. However, 20% of people with SAD have symptoms during the summer months. […] There is no clear answer to why this happens. Scientists have studied several variables, including sunlight exposure and temperature, but they haven’t associated a strong link with summer-pattern SAD. […] However, existing research shows a person with seasonal affective disorder in summer exhibits depressive tendencies, and the brain essentially cannot turn off. […] Researchers believe that the underproduction of serotonin causes depression. Serotonin is known as the happy chemical, and it’s important for mood regulation. Studies have found lower levels in people with depression.
#13 Seasonal Affective Disorder (SAD) (for Parents) | Nemours KidsHealth
https://kidshealth.org/en/parents/sad.html
Seasonal affective disorder (SAD) is depression that happens only at a certain time of year. […] The exact cause of SAD isn’t clear, but some kids’ and teens’ brains react differently to fewer hours of daylight. […] Daylight affects two chemicals in the brain: serotonin and melatonin. When its sunny, the brain makes more serotonin. High levels boost feelings of happiness and well-being. Low levels lead to depression. When its dark, the brain also makes more melatonin. High levels cause you to feel sleepy and have less energy. […] Shorter days and more hours of darkness in fall and winter may decrease serotonin and increase melatonin. This makes depression more likely to happen.
#14 Seasonal Affective Disorder – StatPearls – NCBI Bookshelf
https://www.ncbi.nlm.nih.gov/books/NBK568745/
The results of studies on seasonality and gene activity have variations in gene expression across seasons, with certain genes more active in summer or winter. […] Abnormal serotonin functioning in the central nervous system has also been implicated in SAD, with studies suggesting decreased serotonergic activity and altered serotonin transporter protein levels in affected individuals. Experimental studies have demonstrated the role of tryptophan depletion in triggering depressive symptoms in patients with SAD who had previously responded to bright light therapy, highlighting the involvement of serotonin in the pathogenesis.
#15
https://healthmatch.io/seasonal-affective-disorder/is-seasonal-depression-genetic
Seasonal affective disorder (SAD), also known as seasonal depression, is a common form of major depressive disorder that varies in severity. […] Research has identified a variety of causes of seasonal depression: […] If you have SAD, you underproduce serotonin. This hormone is responsible for mood regulation. […] People with SAD experience higher SERT levels during winter, resulting in low serotonin levels. Researchers think the failure to regulate serotonin can contribute to seasonal affective disorder, particularly when sunlight levels are lower. […] Seasonal affective disorder may have links to genetic mutations; however, scientists don’t believe there is a specific gene mutation that causes it. […] Identifying genes related to SAD vulnerability could help experts craft more optimized, individualized treatment programs.
#16 Brain monoamine oxidase A in seasonal affective disorder and treatment with bright light therapy | Translational Psychiatry
https://www.nature.com/articles/s41398-018-0227-2
Furthermore, we show that SAD may lack seasonal dynamics in brain MAO-A levels. […] The lack of a cross-sectional difference between patients and HC, in contrast to studies in non-seasonal depression, may be due to the milder symptoms typically shown by patients with SAD. […] As is the case in MDD, serotonergic changes are also thought to underlie development of SAD. […] Numerous molecular components of the serotonergic system are influenced by season and light, including the 5-HT1A-receptor and the serotonin transporter (SERT). […] Furthermore, seasonal regulation of SERT expression was shown to be altered in SAD. […] In addition, the efficacy of MAO-A inhibitors in SAD emphasizes that changes to MAO-A may play a role in the disorder’s pathophysiology. […] Our study was motivated by experiments showing increased MAO-A levels in non-seasonally depressed patients.
#17 How to Cope with Seasonal Affective Disorder (SAD) – BuzzRx
https://www.buzzrx.com/blog/winter-blues-or-seasonal-affective-disorder
Seasonal affective disorder, also known as seasonal depression or SAD, is a type of depression that is triggered by seasonal changes. This mood disorder commonly occurs during the colder fall and winter months. A fall in serotonin levels is believed to play a role in the development of SAD. Serotonin is a brain chemical (neurotransmitter) that regulates mood. […] According to experts in mental health services at Cedars Sinai, less sunlight can trigger chemical changes in the brain that can make you feel sluggish and sad. SAD occurs at about the same times every year because decreased exposure to sunlight disrupts the body’s internal clock and causes feelings of depression. […] There are also studies and clinical trials linking melatonin, a sleep-related hormone, to SAD. Melatonin helps to regulate the body’s circadian rhythm or natural sleep-wake cycle. Darkness prompts melatonin to be produced in the pineal gland in the brain. When the days are shorter and darker, more melatonin is made, leading to hypersomnia (increased sleep duration or excessive daytime sleepiness). […] Vitamin D deficiency has been found in people with SAD. This may be due to less sunlight exposure and/or low dietary intake of vitamin-D rich foods. However, research has not shown clearly that taking vitamin D supplementation can prevent or relieve SAD symptoms.
#18
https://www.healio.com/news/optometry/20120225/ocular-mechanism-key-to-light-therapy-for-seasonal-affective-disorder
The specific physiological event that corrects this problem is exposure to adequately timed early morning light. […] When light therapy resets the internal clock to an earlier phase synchronized with the day-night cycle, extremely rapid reversals in clinical depression may result. […] Artificial bright light therapy enters the eye through a retinal receptor mechanism, Dr. Terman said. […] The amount of light at night determines how much melatonin is released from the pineal gland and secreted into the bloodstream, Dr. Bergin said. An inverse relationship exists between the intensity of light exposure and the amount of melatonin secreted. […] Therefore, he said, people who are vulnerable to depression related to light deprivation have a critical need for regular light exposure to allay oversleeping and depression.
#19 Brain monoamine oxidase A in seasonal affective disorder and treatment with bright light therapy | Translational Psychiatry
https://www.nature.com/articles/s41398-018-0227-2
Increased cerebral monoamine oxidase A (MAO-A) levels have been shown in non-seasonal depression using positron emission tomography (PET). […] The serotonergic system is affected by season and light. Hence, this study aims to assess the relevance of brain MAO-A levels to the pathophysiology and treatment of SAD. […] Changes to cerebral MAO-A distribution (1) in SAD in comparison to healthy controls (HC), (2) after treatment with BLT and (3) between the seasons, were investigated in 24 patients with SAD and 27 HC using [11C]harmine PET. […] Cerebral MAO-A distribution volume (VT, an index of MAO-A density) did not differ between patients and HC at any of the three time-points. However, MAO-A VT decreased from fall/winter to spring/summer in the HC group, while SAD showed no change. […] In addition, BLT, but not placebo, resulted in a significant reduction in MAO-A VT.
#20 Brain monoamine oxidase A in seasonal affective disorder and treatment with bright light therapy | Translational Psychiatry
https://www.nature.com/articles/s41398-018-0227-2
We therefore hypothesized that the MAO-A may serve as an endophenotypic link between light, SAD symptoms and their treatment. […] However, we did not find a difference in MAO-A VT between SAD and HC in fall/winter before (PET1) or after BLT treatment (PET2), or in spring/summer (PET3). […] Our results suggest that changes to MAO-A VT in SAD may instead be based on dysregulation of seasonal changes to cerebral expression levels. […] In summary, these results suggest that the serotonergic pathology in SAD might rather be understood as altered dynamic regulation of expression, rather than a static change. […] MAO-A VT decreased after BLT. Lower MAO-A VT would in theory result in a reduction in 5-HT degradation, resulting in higher 5-HT levels and ultimately antidepressant effects. […] This is in analogy to the effects of monoamine oxidase inhibitors and other serotonergic antidepressants such as selective serotonin reuptake inhibitors.
#21
https://healthmatch.io/seasonal-affective-disorder/is-seasonal-depression-genetic
Research has correlated mutations in this gene with seasonal affective disorder. […] Variations in this gene are associated with a greater risk of developing SAD. […] One study has identified a link between SAD and a mutation that makes the eye less sensitive to light. […] However, people with seasonal affective disorder do not have this seasonal rhythm of monoamine oxidase A. This irregularity could be causing too much serotonin to be broken down during winter, contributing to the development of seasonal affective disorder. […] Studies have associated single nucleotide polymorphisms of RGS with depression. […] Genetics research may help experts understand why people react differently to treatment. […] Further research into identifying the genes that play a role in SAD could be valuable. […] While the ultimate cause for seasonal affective disorder remains unknown, genetics definitely play a role in the development of and in people’s susceptibility to this condition.
#22 Genome-wide association study of seasonal affective disorder | Translational Psychiatry
https://www.nature.com/articles/s41398-018-0246-z
Family and twin studies have shown a genetic component to seasonal affective disorder (SAD). […] The authors aimed to identify genetic risk variants for SAD through GWAS. […] No susceptibility loci for SAD were identified at a genome-wide significant level. The strongest association was at an intronic variant (rs139459337) within ZBTB20 (odds ratio (OR)=1.63,p=8.4107), which encodes a transcriptional repressor that has roles in neurogenesis and in adult brain. […] ZBTB20 is a candidate susceptibility gene for SAD, based on a convergence of genetic, genomic, and biological evidence. […] In the current study, we performed a meta-analysis of GWAS for SAD in 1380 cases and 2937 controls of European-American (EA) origin, selected from samples for GWAS of major depressive disorder (MDD) and of bipolar disorder (BD).
#23 Genome-wide association study of seasonal affective disorder | Translational Psychiatry
https://www.nature.com/articles/s41398-018-0246-z
We report that ZBTB20 is a candidate susceptibility gene for SAD, based on a convergence of genetic, genomic, and biological evidence. […] The strongest association evidence was at an intronic variant (rs139459337) within ZBTB20 (odds ratio (OR)=1.63,p=8.4107), which encodes a transcriptional repressor that plays a key role in neurogenesis. […] Our analysis has shown significant enrichment of SAD association signals for candidate gene targets of ZBTB20. This result implies that pathways regulated by ZBTB20 might be important in the etiology of SAD. […] In conclusion, our study identifies ZBTB20 as a candidate susceptibility gene for SAD. Further study in independent samples with the appropriate phenotype data is needed to confirm this association.
#24 Gene Linking Sleep and Seasonal Affective Disorder Found | UC San Francisco
https://www.ucsf.edu/news/2016/02/401646/gene-linking-sleep-and-seasonal-affective-disorder-found
A newly discovered human gene mutation appears to contribute both to unusual sleep patterns and to heightened rates of seasonal depression, according to new research from UC San Francisco. […] Now, by studying three members of a family in which many members experience both FASP and seasonal depression, also called Seasonal Affective Disorder (SAD), the researchers have identified a specific gene mutation that occurs in family members who experience both conditions, suggesting that the gene PER3, a member of the Period family of circadian genes appears to sit at the nexus of sleep and mood. […] This is the first human mutation directly linked to seasonal affective disorder, and the first clear sign of a mechanism that could link sleep to mood disorders, Ptek said. […] To understand how the mutated version of PER3 affects circadian rhythms and depression in the wintertime, Fu and Ptek introduced the mutated form of the gene found in the human FASP family into genetically engineered mice and simulated the effects of changing seasons by altering the length of day and night mice experienced in the lab.
#25 Gene linking sleep and seasonal affective disorder found | University of California
https://www.universityofcalifornia.edu/news/gene-linking-sleep-and-seasonal-affective-disorder-found
A newly discovered human gene mutation appears to contribute both to unusual sleep patterns and to heightened rates of seasonal depression, according to new research from UC San Francisco. […] The researchers have identified a specific gene mutation that occurs in family members who experience both conditions, suggesting that the gene PER3, a member of the Period family of circadian genes appears to sit at the nexus of sleep and mood. […] This is the first human mutation directly linked to seasonal affective disorder, and the first clear sign of a mechanism that could link sleep to mood disorders, Ptek said. […] To understand how the mutated version of PER3 affects circadian rhythms and depression in the wintertime, Fu and Ptek introduced the mutated form of the gene found in the human FASP family into genetically engineered mice and simulated the effects of changing seasons by altering the length of day and night mice experienced in the lab.
#26 Gene Linking Sleep and Seasonal Affective Disorder Found | UC San Francisco
https://www.ucsf.edu/news/2016/02/401646/gene-linking-sleep-and-seasonal-affective-disorder-found
Remarkably, the mutant mice behaved in many ways like humans with FASP, appearing quite normal when day and night were equal, but shifting their circadian rhythms and developing mild depression-like symptoms when exposed to 4-hour days and 20-hour nights. […] Why the PER3 mutation affects mood remains an open question, however, one which the researchers are eager to follow up in their seasonally-sensitive mutant mice by studying how brain circuits known to be connected to mood and depression are impacted when the mice are exposed to either long or short days.
#27 Gene linking sleep and seasonal affective disorder found | University of California
https://www.universityofcalifornia.edu/news/gene-linking-sleep-and-seasonal-affective-disorder-found
Remarkably, the mutant mice behaved in many ways like humans with FASP, appearing quite normal when day and night were equal, but shifting their circadian rhythms and developing mild depression-like symptoms when exposed to 4-hour days and 20-hour nights. […] Why the PER3 mutation affects mood remains an open question, however, one which the researchers are eager to follow up in their seasonally-sensitive mutant mice by studying how brain circuits known to be connected to mood and depression are impacted when the mice are exposed to either long or short days. […] People have known for decades that light and mood were linked, but this is our first real finger-hold on the problem.
#28 Winter makes me SAD: The biological story behind seasonal affective disorder and its potential treatments – ScIU
https://blogs.iu.edu/sciu/2019/03/05/winter-makes-me-sad/
Some studies also suggest that other factors may contribute to SAD, including abnormal melatonin secretion from the pineal gland; irregular retinal sensitivity to sunlight, which may result in atypical activity of photosensitive retinal ganglion cells; decreased vitamin D levels; and deviations in daily cycles of core body temperature and metabolic (i.e., energy-releasing) hormones, such as cortisol. Furthermore, there is evidence that SAD is a consequence of reduced synthesis or dysfunction of serotonin, a chemical messenger that modulates mood and regulates physiological processes related to cognition, reward, learning, and memory. […] Although the physiological irregularities that result in SAD are still being explored, several treatments are effective in alleviating its symptoms. […] Light therapy is one of the most successful treatment options for patients with SAD.
#29 Seasonal Affective Disorder
https://www.uspharmacist.com/article/seasonal-affective-disorder-1
Although there is some evidence supporting the use of second-generation antidepressants for SAD, a Cochrane review has highlighted insufficient evidence to draw overall conclusions regarding their efficacy. […] Psychotherapy, particularly cognitive-behavioral therapy (CBT), can help individuals develop coping strategies to manage symptoms and identify negative thought patterns associated with the disorder. […] Melatonin supplementation has also been explored as a treatment option for SAD. […] Additionally, low levels of vitamin D have been associated with SAD, as vitamin D plays a role in serotonin regulation in the brain. […] Daily walks outsideeven on cloudy dayscan significantly improve SAD symptoms, especially when combined with light therapy. […] A study showed that patients who took daily walks for 60 minutes each morning alongside light therapy had greater improvement in symptoms than those who only received light therapy.
#30 Seasonal Affective Disorder
https://www.uspharmacist.com/article/seasonal-affective-disorder-1
The exact cause of SAD remains unclear, but several theories have been proposed to explain its development. One theory suggests that disruptions in an individuals internal clock, known as circadian rhythm, play a role. […] Another related theory, the phase shift hypothesis, suggests that seasonal changes disrupt the timing of our circadian rhythm, affecting various bodily processes like melatonin production and body temperature regulation, potentially leading to winter blues symptoms. […] Additionally, individuals with SAD may have a problem with how sensitive their retinas are to light. […] Furthermore, individuals with winter depression often show increased activity of the serotonin transportera molecule responsible for removing serotonin (a neurotransmitter important for mood regulation) from circulation.
#31
https://www.healio.com/news/optometry/20120225/ocular-mechanism-key-to-light-therapy-for-seasonal-affective-disorder
Supplementation of light, particularly in the early hours of the day, has been known to have a salutary effect on major depressive disorders, as well as mood disorders that fall short of a psychiatric diagnosis. Light therapy was originally intended as a treatment specifically for seasonal affective disorder (SAD), but has since been found to be beneficial in treating depression at any time of year. […] Dr. Terman, a professor in the Department of Psychiatry at Columbia University, director of the Center for Light Treatment and Biological Rhythms at New York-Presbyterian Hospital and director of Clinical Chronobiology at New York State Psychiatric Institute, said an ocular mechanism plays a key role in the absorption of light therapy into the body. […] We now know from 20 years of research that it is an ocular mechanism; we are not responding to light stimulation through the skin, he said.
#32
https://www.healio.com/news/optometry/20120225/ocular-mechanism-key-to-light-therapy-for-seasonal-affective-disorder
We absolutely need this ocular signal in the morning to stay in synch with our external world, he said. […] Dr. Terman said an individuals internal clock is genetically predetermined, and often does not run on an exact 24-hour cycle. […] Dr. Terman said cumulative exposure to this narrow band of the visible spectrum might exacerbate the progression of age-related macular degeneration. […] Dr. Bergin agreed that UV light should be avoided in light therapy. […] Dr. Terman said, however, that some blue light exposure is important to the bodys circadian rhythm. […] Dr. Terman also discussed the recommended intensity of light exposure. […] Treatment with a light intensity of 10,000 lux usually calls for a duration of 30 minutes per day, he said. […] Dr. Bergin said optometrists are able to play a role in noticing signs of SAD and guiding patients toward proper treatment.
#33 Seasonal Affective Disorder: SAD Symptoms, Causes, Self-Care
https://www.helpguide.org/mental-health/depression/seasonal-affective-disorder-sad
Seasonal affective disorder (SAD) is a form of depression that occurs at the same time each year, usually in winter. […] While the exact causes of seasonal affective disorder are unclear, most theories attribute the disorder to the reduction of daylight hours in winter. The shorter days and reduced exposure to sunlight that occurs in winter are thought to affect the body by disrupting: […] Your body’s internal clock or sleep-wake cycle responds to changes between light and dark to regulate your sleep, mood, and appetite. […] The reduced sunlight of winter can lower your body’s production of serotonin, a neurotransmitter that helps to regulate mood. A deficit may lead to depression and adversely affect your sleep, appetite, memory, and sexual desire. […] Light therapy aims to replace the missing daylight of winter by exposing you to bright light that mimics natural outdoor light. […] Light therapy has been shown to be effective in up to 85 percent of SAD cases. […] Cognitive behavioral therapy (CBT) can be highly beneficial for people with seasonal depression. […] SSRI antidepressants work by acting on serotonin levels in the brain to reduce SAD symptoms.
#34 Seasonal affective disorder – Wikipedia
https://en.wikipedia.org/wiki/Seasonal_affective_disorder
Seasonal mood variations are believed to be related to light. An argument for this view is the effectiveness of bright-light therapy. […] There is evidence that many patients with SAD have a delay in their circadian rhythm, and that bright light treatment corrects these delays which may be responsible for the improvement in patients. […] The symptoms of it mimic those of Dysthymia or even major depressive disorder. […] There is also potential risk of suicide in some patients experiencing SAD.
#35 Seasonal Affective Disorders | AAFP
https://www.aafp.org/pubs/afp/issues/1998/0315/p1340.html
Seasonal affective disorder is a pattern of major depressive episodes that occur and remit with changes in seasons. […] While questions regarding the validity of seasonal affective disorder as a syndrome and the mechanism of action of light therapy continue to be investigated, the established effectiveness of light therapy in patients with winter depression supports the usefulness of assessment for this seasonal pattern and consideration of light therapy as an option in addition to existing treatment choices. […] Although phototherapy has proved effective in the treatment of winter depression, its mechanism of action has not been established. Several mechanisms have been advanced, including circadian phase shifting, or reversing the increased melatonin, decreased 5-hydroxytryptamine and decreased dopamine neurotransmission observed in SAD, but it remains unestablished whether phototherapy achieves its well-documented effects through any of these or other mechanisms. […] Predictors of a positive response to light therapy include disorders characterized by a history of hypersomnia, a preponderance of atypical vegetative symptoms and an increased intake of sweet foods in the afternoon, as well as a history of reactivity to ambient light.
#36 HKU Scholars Hub: Pathophysiological mechanism of seasonal affective disorder
https://hub.hku.hk/handle/10722/89451
Despite the long history in medicine, the pathophysiological mechanism(s) of seasonal affective disorder (SAD) remain largely unknown. […] By employing a meta-analytic methodology, the authors of this study attempted to verify the validity of different pathophysiological mechanism(s) proposed for SAD. […] The findings showed that for phototherapy of medium light intensity, a combination of morning-evening therapy regime yielded the best therapeutic effect, and the antidepressant effect of the morning-evening light regime was superior to a single pulse of light administered at other times of day. […] Furthermore, the data showed that the antidepressant effect of a single pulse of light was similar for morning, midday, and evening light. […] These findings supported the photon-count hypothesis and refuted the proposed photoperiod, melatonin, and phase-shifting models of SAD.
#37 Seasonal Affective Disorder (SAD) Medication: Antidepressants, SSRIs, Antidepressants, SNRIs, Antidepressants, Dopamine/Norepinephrine Reuptake Inhibitors, Antidepressants, TCAs, Antidepressants, MAO Inhibitors
https://emedicine.medscape.com/article/2500054-medication
The data are limited with regard to psychoactive medications and their use in the treatment of seasonal affective disorder. At the present time, the serotonin reuptake inhibitors (SSRIs) fluoxetine and sertraline have been the most studied and appear to be effective. […] According to the American Psychiatric Association, SAD (Major Depressive Disorder, with seasonal pattern) can be treated with the entire range of medication treatments available to treat Major Depressive Disorder. […] Of note, while bupropion XL is an established treatment for the prevention of SAD (and is FDA approved for this indication), the evidence for the treatment of SAD is more limited. […] The drugs mechanism of action is thought to be the potentiation of serotonergic activity in the CNS resulting from the inhibition of CNS neuronal reuptake of serotonin.
#38 Seasonal Affective Disorder: More Than Just Winter Blues | Rosecrance
https://www.rosecrance.org/blog/seasonal-affective-disorder-more-than-just-winter-blues/
Medications designed to treat depression, known as antidepressants, can be particularly beneficial for individuals experiencing SAD, especially when used on their own or in conjunction with talk therapy. These antidepressants function by modifying how the brain produces or utilizes specific neurotransmitters and chemicals that play crucial roles in regulating mood and managing stress responses.
#39 Seasonal Affective Disorder (SAD) Medication: Antidepressants, SSRIs, Antidepressants, SNRIs, Antidepressants, Dopamine/Norepinephrine Reuptake Inhibitors, Antidepressants, TCAs, Antidepressants, MAO Inhibitors
https://emedicine.medscape.com/article/2500054-medication
Fluoxetine is an antidepressant agent that is chemically unrelated to the tricyclic, tetracyclic, or other available antidepressants. It selectively inhibits presynaptic serotonin reuptake with minimal or no effect on the reuptake of norepinephrine or dopamine. […] Paroxetine is a potent selective inhibitor of neuronal serotonin reuptake. It also has a weak effect on norepinephrine and dopamine neuronal reuptake. […] Sertraline selectively inhibits presynaptic serotonin reuptake, with minimal or no effect on reuptake of norepinephrine or dopamine. […] Duloxetine is a potent inhibitor of neuronal serotonin and norepinephrine reuptake. Its antidepressive action is theorized to be due to serotonergic and noradrenergic potentiation in the CNS. […] Tranylcypromine inhibits the enzyme monoamine oxidase, which is responsible for the breakdown of neurotransmitters, thereby increasing endogenous concentrations of epinephrine, norepinephrine, and serotonin. […] Phenelzine is usually reserved for patients who cannot tolerate or do not respond to TCAs or SSRIs. Inhibits the enzyme monoamine oxidase, which is responsible for the breakdown of neurotransmitters, thereby increasing endogenous concentrations of epinephrine, norepinephrine, and serotonin.
#40 Bupropion (Wellbutrin, Zyban, and others): Uses, Side Effects, Interactions, Pictures, Warnings & Dosing – WebMD
https://www.webmd.com/drugs/2/drug-13509/wellbutrin-oral/details
Bupropion is used to treat depression, seasonal affective disorder (SAD), and to help you quit smoking. It works by regulating chemicals in your brain called norepinephrine and dopamine. […] Bupropion is commonly used to treat the following conditions. […] Seasonal affective disorder (SAD), also known as seasonal depression. […] Bupropion works to regulate chemicals in your brain called norepinephrine and dopamine.
#41 Psychiatry.org – Seasonal Affective Disorder (SAD)
https://www.psychiatry.org/patients-families/seasonal-affective-disorder
Seasonal affective disorder is a form of depression also known as SAD, seasonal depression or winter depression. […] SAD has been linked to changes in the brain prompted by shorter daylight hours and less sunlight in winter. […] SAD can be effectively treated in several ways, including light therapy, antidepressant medications, talk therapy or some combination of these. […] Light therapy involves sitting in front of a light therapy box that emits a very bright light (and filters out harmful ultraviolet (UV) rays). […] Talk therapy, particularly cognitive behavior therapy (CBT), can effectively treat SAD. […] With the right treatment, SAD can be a manageable condition.
#42 All about seasonal affective disorder – Mayo Clinic Health System
https://www.mayoclinichealthsystem.org/hometown-health/speaking-of-health/seasonal-affective-disorder-more
On average, SAD will last about five months of the year. […] Bright light therapy is considered an effective treatment for SAD. […] An antidepressant prescribed by a healthcare professional can be an effective treatment option. […] Research has shown that exercising for 20 minutes at least three days a week has similar effectiveness to taking an antidepressant. […] CBT is an effective treatment for SAD and clinical depression. […] Because SAD is tied to the changing seasons, the onset can be predicted, which sets a person up to better manage their symptoms.
#43 (PDF) Pathophysiology of seasonal affective disorder: a review
https://www.academia.edu/1371259/Pathophysiology_of_seasonal_affective_disorder_a_review
The study of the pathophysiology of seasonal affective disorder (SAD, also known as winter depression) has historically been intimately linked to investigations into the mechanisms of action of light therapy. This paper reviews the studies on the pathophysiology of SAD with emphasis on circadian, neurotransmitter, and genetic hypotheses. There is substantial evidence for circadian phase shift and serotonergic hypotheses, but conflicting results may indicate that SAD is a biologically heterogeneous condition. Recent progress in defining the molecular mechanisms of the human circadian clock and retinal phototransduction of light will provide important new directions for future studies of the etiology and pathophysiology of SAD. […] The etiology and pathophysiology of seasonal affective disorder (SAD) has been linked to the seasons and to light since its first conceptualization. Aspects of SAD that make it particularly amenable to biological investigation include the predictable recurrent episodes, the rapid response to a nonpharmacologic treatment, the specific neurovegetative features, and the availability of rich animal models of seasonality. This paper reviews new findings for the major biological hypotheses for SAD, focusing on circadian rhythms, neurotransmitters, and molecular genetics. Integrative issues and future directions for the study of SAD, including the heuristic value of a dual-vulnerability hypothesis that conceptualizes seasonality as a dimensional construct and the importance of studying endophenotypes, will be discussed.
#44 Winter makes me SAD: The biological story behind seasonal affective disorder and its potential treatments – ScIU
https://blogs.iu.edu/sciu/2019/03/05/winter-makes-me-sad/
In fact, this treatment is so successful that universities and public libraries in parts of the northern U.S. and Canada offer free light therapy stations to people suffering from SAD. […] Furthermore, recent work suggests that cognitive-behavioral therapy and medication may also be effective options for treating SAD. In particular, antidepressants and selective serotonin reuptake inhibitors (SSRIs), which increase serotonin levels in the brain, have had some success in relieving the psychological symptoms associated with SAD.
#45 Seasonal Affective Disorder
https://www.uspharmacist.com/article/seasonal-affective-disorder-1
SAD is a complex and undertreated psychiatric condition that can significantly impact individuals who experience symptoms. […] SAD presents various treatment options, ranging from nonpharmacologic to pharmacologic interventions, mainly aimed at alleviating symptoms of depression. […] By acknowledging awareness, facilitating access to resources, and promoting adherence to treatment regimens, pharmacists can help patients make crucial decisions in improving their mental health outcomes.