Serotonin transporter gene status predicts caudate nucleus but not amygdala or hippocampal volumes in older persons with major depression

BackgroundAlthough the short allele of the serotonin transporter promoter polymorphism (5-HTT) has been linked to increased risk of major depression in early adult life, its relationships with late-life depression and to changes in subcortical nuclei remain unclear.Methods5-HTT genotypes (SS, SL, LL) were determined for 45 older persons with major depression (mean age = 52.0, sd = 12.8) and 16 healthy controls (mean age = 55.8, sd = 10.3). MRI-derived volumes of the amygdala, hippocampus, caudate and putamen were determined by reliable tracing techniques.ResultsIn those with depression, the short allele of 5-HTT was associated with smaller caudate nucleus volumes. Although hippocampal and amygdala volumes were smaller in those with depression as compared with control subjects, 5-HTT gene status did not predict this reduction in size.LimitationsThe findings are limited by the number of clinical and control participants.ConclusionsReduced caudate nucleus volume in older patients with major depression was associated with the short allele of the 5-HTT gene. This regional brain change may be a consequence of early developmental expression as well as later vascular or degenerative effects of this genotype.