Late-onset minor and major depression: early evidence for common neuroanatomical substrates detected by using MRI

Abstract

The purpose of our study was to examine the neuroanatomical correlates of late-onset minor and major depression and to compare them with similar measures obtained from nondepressed controls. Our study groups were comprised of 18 patients with late-onset minor depression, 35 patients diagnosed with late-onset major depression, and 30 nondepressed controls. All subjects were scanned by using a 1. 5-tesla MRI scanner. Absolute whole brain volume and normalized measures of prefrontal and temporal lobe volumes were obtained and used for comparison among groups. Our findings indicate that patients with minor depression present with specific neuroanatomical abnormalities that are comparable with the major depression group but significantly different from the controls. Normalized prefrontal lobe volumes show a significant linear trend with severity of depression, with volumes decreasing with illness severity. Whole brain volumes did not differ significantly among groups. These findings have broad implications for the biology of late-life depression and suggest that there may be common neurobiological substrates that underlie all clinically significant forms of late-onset mood disturbances.

Figure 1

A bar graph depicting normalized prefrontal and temporal lobe volumes in the three groups. CTL, controls; MIN, minor depression; MDD, major depression; F/CV, prefrontal volume/cranial volume; T/CV, temporal lobe volume/cranial volume. ∗, significantly different from controls, P < 0.05. SD bars are depicted in the figure.

Figure 2

A regression plot for normalized prefrontal volume in all of the three groups after age and gender corrections. F/CV, prefrontal volume/cranial volume