Serotonin System Dysfunction:
Independent correlations with  suicidal
behavior and depression
Deficient serotonergic neurotransmission has been
hypothesized as a cause of major depression for 30
years. Depression is a complex disorder and
involves many brain regions.
Deficient serotonergic function is also associated
with suicidal behavior. Suicidal behavior involves
a basic decision regarding life or death, likely
involving a small part of the brain.