Reduced gray matter brain volumes are associated with variants of the serotonin transporter gene in major depression

The serotonergic system is involved in the pathophysiology of major depression as well as in the early central nervous system development and adult neuroplasticity. The aim of the study was to examine in 77 patients with major depression and 77 healthy controls the association between the triallelic polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) and gray matter (GM) brain volumes measured with 1.5 T magnetic resonance imaging. Voxel-based morphometry were estimated on magnetic resonance images and genotyping was performed. We found that healthy controls have a strong association between the 5-HTTLPR and GM volumes of the dorsolateral prefrontal cortex, left anterior gyrus cinguli, left amygdala as well as right hippocampus, whereas there is no such association in patients with major depression. Healthy subjects carrying the S- or LG-allele have smaller GM volumes than those with the LA-allele, indicating that 5-HTTLPR contributes to the development of brain structures. Patients with depression show reduced GM volumes, particularly when they are homozygous for the LA-allele, suggesting that these patients are more vulnerable for morphological changes during depressive episodes.