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Stress, Short Serotonin Gene May Have Role in Depression

Serotonin transporter gene variant in combination with life stress overactivates amygdala

THURSDAY, Oct. 12 (HealthDay News) -- A combination of stress and having a variant of the serotonin transporter gene may predispose a person to depression by causing overactivation of the amygdala, according to a report published online Oct. 10 in the Proceedings of the National Academy of Sciences Early Edition.

Turhan Canli, Ph.D., of Stony Brook University in Stony Brook, N.Y., and colleagues used brain imaging analysis, genotyping and questionnaires to investigate the underlying neural mechanism causing depression in individuals carrying the serotonin gene variant. The variation is caused by a shortened repeat length in a region controlling expression of the serotonin transporter gene.

In subjects with the short version of the gene, the investigators found that the amygdala responded differently to negative emotional stimuli and was overactivated in the resting state compared with those with the long version. The differences were even more pronounced in subjects with high stress.

"Life stress also differentially affected, as a function of serotonin transporter genotype, functional connectivity of the amygdala and hippocampus with a wide network of other regions, as well as gray matter structural features, and affected individuals' level of rumination," the authors write. "These interactions may constitute a neural mechanism for epigenetic vulnerability toward, or protection against, depression."

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