Thursday, September 4, 2008

Seasonal mood disorders and the brain

Summer is almost over and fall will soon make its debut. Honestly, I can't wait, because I am sick of 90+ degree temperatures! Fall is my favorite season, but at the same time, I do have a tendency to get a bit sadder, missing the sunlight.

Seasonal mood disorders, also known as Seasonal Affective Disorder (SAD) affect many people worldwide. SAD is a type of depression that occurs cyclically with the change of seasons. The majority of people experience SAD during the fall and winter months, but it can also occur with the spring and summer months. Though symptoms do not necessarily qualify for major depression, SAD does impair the quality of life for certain individuals. Symptoms include depression, fatigue, changes in appetite, oversleeping, social withdrawal, anxiety, irritability, insomnia, agitation, increased sex drive. Some people also experience reverse SAD, with symptoms higher energy levels, increased sociability, and elevated moods.

The causes of SAD are unknown but clinicians feel circadian rhythms, melatonin, and serotonin can all have an impact. Other factors for SAD are a family history and living in northern locations. Treatment for SAD is similar to major depression with medications and psychotherapy. Light therapy can also be used for SAD during the fall/winter months.

Recent research for SAD has looked at the variable serotonin levels in the brain. In this article from the Archives of General Psychiatry, titled seasonal variation in human brain serotonin transporter binding, scientists studied the brain through Positron Emission Tomography (PET) scans. The serotonin transporter is significant in regulating the intensity and spread of serotonin signals across the brain.

In this study, 88 individuals underwent a PET scan to assess serotonin transporter binding potential value, an index of serotonin density. Each scan was grouped into fall and winter or spring and summer.

The results showed that individuals in the fall and winter group had significantly higher serotonin transporter binding potential value which means less serotonin was circulating throughout their brain than the spring and summer group.This may explain the hyposerotonergic symptoms like lack of energy, fatigue, oversleeping, and overeating that often occur during this time in those individuals who experience SAD. Thus, this provides more physiological evidence of the role of serotonin and variability of seasons throughout the brain.

5 comments:

KC Elaine said...

your posts are always so informative! thanks for that. fortunately I don't have SAD, but I do love the sunshine.

Tiptoe said...

Kyla, thanks for the compliment. Yes, sunshine is nice, as long as high humidity isn't involved. ;-)

Charlynn said...

I had a horrible time with SAD last year - it ended up leading back into full-blown clinical depression, which I have struggled with on and off in the past. Highs are already hitting no greater than the 70s here and I am in mourning of what was an awesome but awfully short summer.

I really should move somewhere with a warmer climate. :P

Tiptoe said...

Charlynn, yeah SAD can wind up getting out of hand. I hope you will be able to fight it off this year.

I hear you about the climate, but then again, I'd miss the seasons.

Charlynn said...

I'd miss the seasons, too, only we don't have them for long where I live. We virtually go from winter to summer, have summer for three months, a short fall, and then winter again. It's usually way too cold for too long around here for my liking. When my husband and I both finish our degrees, we should be able to get a job anywhere in the country. When that happens, I'd love to try someplace completely different from here and see how it is. :)