"The researchers studied 73 drug-free patients with seasonal affective disorder (SAD) and 70 people without the condition. People with SAD get depressed in the autumn and winter, and often go into remission in the spring and summer. So-called “bright light therapy” – where sufferers stare at brightly lit screens – can also relieve symptoms.Hmm....that's the reason my winter blue takes a spike in blistering cold, and that's why it takes a hike in summer bold. Who said "depression" cannot be rhythmic and poetic?
The researchers were interested in these patients’ serotonin transporter (SERT) – a molecule that "pumps" serotonin back into cells. SERT is expressed in blood platelets, so they drew blood at three points in time: in the autumn or winter (when patients were experiencing seasonal depression), after four weeks of light therapy, and again in summer.
They tested the platelets to see how much SERT was expressed there, and found levels were normal in both groups. They then measured how many times per minute the SERT would go to work removing serotonin, and here they found significant differences.
In blood taken during winter depression, SAD patients had significantly more removal events per minute than those in the healthy control group – about 350 compared with 200."
Chemical clue sheds light on winter depression