COGNITIVE PERFORMANCE IN TESTS SENSITIVE TO FRONTAL-LOBE DYSFUNCTION IN THE ELDERLY DEPRESSED

The paper reports the profile of impairment across a variety of cognit ive functions with special emphasis on tests sensitive to frontal lobe dysfunction, in 24 elderly depressed patients during and on recovery from mood disorder, compared with 15 age- and sex-matched controls. Tr aditional neuropsychological tests and a recently developed battery of computerized tests (CANTAB) were used. Impairments were found in the depressed group compared to controls and to themselves on recovery acr oss all domains examined. The depressed group showed deficits on visuo spatial recognition memory, attentional shifting at the extra-dimensio nal shift stage and in measures of both processing and motor speed wit hout impaired accuracy in a visual search task. Impairments were also found on a planning task with disproportionately increased numbers of moves needed for more difficult problems and evidence of both slowed m otor response and increased processing time once the task was commence d. Performance on recovery improved across all tasks. Comparisons were made with the performance of patients suffering from dementia of the Alzheimer type (DAT) and Parkinson's disease on similar tests. Respons e latencies in test performance were found to correlate with the numbe r of episodes of depression suffered and with ventricular size on CT s can, as measured by computerized planimetry. On recovery, residual dep ression scores correlated with latency of test performance and with ve ntricular brain ratio. The results, thus, show that depression in the elderly is associated with a significant degree of deficit on tests se nsitive to frontostriatal dysfunction. Some of the deficits appear spe cific to depression and some do not remit following clinical recovery. However, these impairments have to be interpreted in the context of a broad profile of cognitive deficit.