THE PATHOPHYSIOLOGIC BASIS FOR LATE-LIFE DEPRESSION - IMAGING STUDIESOF THE AGING BRAIN

Available evidence on late-life depression does not support the concep t that psychological or social factors are the sole contributors. Seve ral studies suggest that there is a lower genetic lending to late-onse t depression; thus, late-life depression may be attributable to other factors, such as cerebrovascular changes. With magnetic resonance imag ing (MRI), researchers can note, examine subtle cerebrovascular change s in the brain. The aging process and related medical illnesses are as sociated with leukoencephalopathy, which includes periventricular hype rintensities and deep white-matter hyperintensities (DWMH), also assoc iated with carotid atherosclerosis; both characteristics are detectabl e on MRI scans. Brain MRI studies of older depressed patients suggest that cerebrovascular pathology plays a major role in etiology, and ima ging studies of stroke patients can clarify neuroanatomic substrates f or the emergence of depression. There is also a correlation between th e severity, of DWMH and the severity, of myocardial infarction. Other possible etiologies for late-life depression include endocrine disorde rs and the phenotypic apolipoprotein E alleles E4/4 and E4/3.