BRAIN-STEM EVOKED-RESPONSE ABNORMALITIES IN LATE-LIFE DEPRESSION WITHVASCULAR-DISEASE

Objective: The purpose of this study was to examine whether the brains tem evoked responses of geriatric depressed patients with vascular dis ease show greater changes in wave V latency after increased stimulatio n than do responses of geriatric depressed patients without vascular d isease and elderly comparison subjects with and without vascular disea se. Method: Geriatric patients with unipolar depression (N=53) were re cruited from a university psychiatric hospital. Elderly comparison sub jects (N=23) were recruited through advertisements. All subjects were assessed for depressive symptoms, cognitive performance, overall medic al burden, vascular disease, and disability. Brainstem evoked response was elicited at stimulation rates of 11.4 and 80.0 clicks/sec. Result s: The interaction between depression and vascular disease had a signi ficant effect on change in wave V latency. This effect was synergistic , more than an additive effect. Post hoc comparisons showed that the d epressed patients with vascular disease had greater changes in wave V latency than did the depressed patients without vascular disease, comp arison subjects with vascular disease, and comparison subjects without vascular disease. Linear discriminant function analysis showed that 8 2% of the subjects with abnormal changes in wave V latency (sensitivit y: 75%, specificity: 81%) could be identified on the basis of ratings for depression and for vascular disease. Conclusions: Demyelination af flicting the pens and mesencephalon may explain the greater change in wave V latency for the brainstem evoked response in depressed patients with vascular disease. Further studies combining brainstem evoked res ponse with brain imaging may determine whether depression develops onl y after vascular disease leads to demyelination.