Scientists at The University of Copenhagen have revealed that they’re pretty confident they know what the cause of seasonal affective disorder is and why it affects some people and not others.
Research was conducted on 34 participants who volunteered to have brain scans performed. Although thirty-four people isn’t very many, the consistency of findings in 11 of them brought more certainty. 24 of the people did not suffer from seasonal depression while the other 11 did. This way the scientists could study the brain scans and see what was normal compared to what was not in the subjects who have SAD.
The findings were that in the eleven people scanned there was an increased production of a transporter protein that depletes serotonin. A serotonin transporter (SERT) moves serotonin back into nerve cells where it becomes inactive. As a result, the higher the SERT in patients the lower their serotonin levels.
The difference between people who are not affected by SAD and those who are is that individuals who don’t experience depression during the winter have serotonin levels that remain at a normal level. Individuals who have SAD may have a higher SERT (transport of serotonin back to an inactive state) which lowers the neurotransmitter.
What’s also important to note about this study is that it was designed to monitor activity in the brain throughout the year so that scientists could get a closer look during both summer and winter.
The major takeaway here is that the volunteers who had SAD experienced a major drop in serotonin during the winter months compared to others.