A volumetric study of MRI signal hyperintensities in late-life depression

Objective: An increase in white-matter lesions has been previously described in older subjects with depression. The authors investigated whether the regional location varied between depressed and normal subjects and determined the relationship of magnetic resonance (MR) signal hyperintensities to known clinical risk factors for vascular disease. Methods: Authors used automated image-processing software to determine volumes of signal hyperintensities from MR brain scans of older people with depression (N = 29; mean age: 76 years) and normal subjects of similar age (N=32). Results: Overall, subjects with depression had a significantly greater frontal-lobe white-matter lesion volume than normal subjects (0.35% versus 0.22%). However, after excluding subjects with hypertension, diabetes, or ischemic heart disease (leaving 14 depressed and 15 normal subjects), we found even greater differences between groups, with a larger volume of MR signal hyperintensities in the frontal region of the depressed group, but no difference in the basal ganglia or parietal and occipital lobes. Conclusion: The results support the "vascular depression" hypothesis and suggest that those with depression but without traditional vascular risk factors may be much more susceptible to cerebrovascular disease than normal subjects. The mechanisms for this increased susceptibility remain to be determined.