Brain Hormone Tied to Seasonal Affective Disorder
Serotonin levels shrink with the daylight, study finds
THURSDAY, Dec. 5, 2002 (HealthDayNews) -- New research on the hormone serotonin provides more proof that the effect of sunlight on brain neurotransmitters is a significant factor in seasonal mood disorders.
That's the finding of a report by Australian scientists in this week's issue of Lancet.
Previous evidence suggested serotonin plays a role in causing seasonal depression. However, scientists had found that concentrations of serotonin and other neurotransmitters, such as dopamine and norepinephrine, are normal in the cerebrospinal fluid of people with seasonal affective disorder.
The Australian researchers used a more accurate method of assessing serotonin concentrations in the brain. They measured the serotonin concentrations in blood vessels draining the brain.
They took blood samples from the jugular veins of 101 healthy men and compared serotonin levels based on weather conditions and seasons. They found the turnover of serotonin was lowest in the winter and the amount of serotonin produced by the brain was directly linked to prevailing sunlight duration.
The National Mental Health Association has more about seasonal affective disorder.