Caudate nucleus volumes and genetic determinants of homocysteine metabolism in the prediction of psychomotor speed in older persons with depression.

The authors sought to determine whether caudate nucleus volumes or specific genotypes predict psychomotor slowing in older persons with depression. Forty-seven persons with depression (mean age=51.8 years, SD=12.4) and 20 healthy volunteers (mean age=56.1 years, SD=9.8) underwent clinical assessments, a neuropsychological test of psychomotor speed (part A of the Trail Making Test), high-resolution magnetic resonance imaging scans, and genotyping for the apolipoprotein E epsilon4 allele and a mutation of the methylenetetrahydrofolate reductase enzyme. Multivariate analyses revealed that psychomotor speed was uniquely predicted by age, a diagnosis of depression, right caudate nucleus volume, and mutation of the methylenetetrahydrofolate reductase enzyme. Psychomotor slowing, a key clinical and cognitive phenomenon in older persons with depression, is predicted by reduced caudate nucleus volumes and genetic determinants of homocysteine metabolism.