2-Minute Neuroscience: Seasonal Affective Disorder

Seasonal affective disorder is a subtype of depression or bipolar disorder in which symptoms appear at specific times of the year and go into full remission at other times. In this video, I discuss some of the hypothesized neurobiological mechanisms underlying seasonal affective disorder.

TRANSCRIPT:

Seasonal affective disorder is a subtype of depression or bipolar disorder in which symptoms appear at specific times of the year and go into full remission at other times. The condition most commonly develops during fall or winter, but spring or summer cases do also occur. In order to be diagnosed with seasonal affective disorder, someone must meet the criteria for major depressive disorder or bipolar disorder, but also display seasonal patterns with their symptoms for at least two years.

The mechanisms underlying seasonal affective disorder are not fully understood, and are likely not the same in every case. One hypothesis is that seasonal affective disorder is linked to a disruption in circadian rhythms, the 24-hour cycles that regulate the function of our bodies. According to this hypothesis, in some individuals circadian rhythms may not adjust appropriately when the length of the day changes with the seasons. This could lead to a misalignment of circadian rhythms and environmental light, as well as a misalignment of biological processes like melatonin release and sleep. While this does not seem to explain all cases of seasonal affective disorder, it does provide an explanation for why exposure to very bright light, as is done in bright light therapy, has been found to be effective in treating some cases of the disorder.

Several other hypotheses have been proposed to explain seasonal affective disorder, some of which might be also linked to circadian rhythm disruption. For example, studies have found that some individuals with seasonal affective disorder might have deficiencies in retinal sensitivity to light. Other studies suggest low levels of vitamin D could play a role in some cases, and abnormalities in levels of neurotransmitters like serotonin and norepinephrine have also been implicated.

REFERENCES:

Galima SV, Vogel SR, Kowalski AW. Seasonal Affective Disorder: Common Questions and Answers. Am Fam Physician. 2020 Dec 1;102(11):668-672. PMID: 33252911.

Rohan KJ, Roecklein KA, Haaga DAF. Biological and Psychological Mechanisms of Seasonal Affective Disorder: A Review and Integration. Current Psychiatry Reviews. 2009;5:37-47.

Sohn CH, Lam RW. Update on the biology of seasonal affective disorder. CNS Spectr. 2005 Aug;10(8):635-46; quiz 1-14. doi: 10.1017/s109285290001960x. PMID: 16041295.

[ilyas_elouchihi]

I'm a health psychology student and I never miss an upload by you! 😁

[Pixietink]

With the heatwaves my mental health is gone for a toss

[gaylecheung]

Absolutely agree, along with my internal clock

[Neurobsessed]

Do one on dyslexia and another on dyspraxia.

[robertoswalt]

In the 1990s I wondered to myself why I would choose to eat my lunch outside with weather extremes instead of inside at the break room table. I eventually tracked it down to my working in a room with no windows and poor lighting. As I started becoming aware of the effects of sun light on me, I realized that I could help my mood by using 5000K lighting.

[neurostudywithme]

Can you please do a video about habenula, thanks❤

[terenzo]

I wonder if there are any known cases of folks who live in Southern California where we don't really have well-defined seasons -- all the times of the year are roughly similar.

[FunkZoneFitness]

Santa Barbara has a weird May gray / June gloom phenomenon that’s debilitating for some

[Monica_M]

Interesting 🤔 I have noted my equilibrium is affected when there are changes in the barometric pressure.

[firstlast-emyq]

This is wrong! SAD is not a subtype of depression or bipolar disorder; it is only a SPECIFIER. A specifier and a subtype are both ways to provide more detail about a diagnosis, but they serve different purposes. Subtypes categorize distinct forms of a disorder, while specifiers add detailed descriptions that can apply across different subtypes.