Seasonal Affective Disorder linked to mutation

The cold and short days of winter usually make people eat and sleep more. Some may even have cabin fever or claustrophobia from being indoors most days. These are normal reactions for most of us during the fall to winter season. However, a person who suffers from seasonal affective disorder may experience more serious reactions than just the "winter blahs".

A severe type of depression, seasonal affective disorder (SAD) affects about 6 percent of the US population. The symptoms and mood changes can be devastating, and come back year after year. It is usually treated with a light therapy where a SAD patient is exposed to bright light in the mornings to trick the brain into believing that the days are longer.

A new study  finds a mutation in the melanopsin gene makes a SAD patient require more light to function normally.  Melanopsin is a photopigment that helps regulate circadian rhythms and other non-visual responses in the eye. An individual with two copies of the mutation in the melanopsin gene is five times more likely to have symptoms of SAD, the Journal of Affective Disorders report in its December issue. Not every person with SAD has the mutation, but those who have the mutation may be predisposed to developing SAD. Of course,  further studies are needed, but understanding the melanopsin mutation may help improve treatments.

via: Science Daily; Image: Flickr