Recognition memory and response bias in elderly demented, depressed, and demented/depressed patients




McQuaid, Monica Mary

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Elderly depressed patients are often referred for a neuropsychological examination to evaluate their cognitive abilities and to assist in making a differential diagnosis of dementia vs. depression when the etiology of presenting symptoms is unclear. Indices of discrimination (i.e., the ability to identify target from distractor items during recognition memory testing) and response bias (i.e., the probability of saying "yes" to an item when uncertain if it is a target or a distractor) have been suggested as useful aids when making such a differential diagnosis. Prior research indicated that discrimination abilities were significantly better in depressed elderly as compared to demented elderly and that depressed patients used the most conservative response strategy (i.e., they tended to say "no" more often when uncertain) while demented patients had a more liberal response style (i.e., they tended to say "yes" more often). However, little is known about the performance of patients with dementia complicated by depression. This study attempted to address the nature of discrimination ability and response bias in patients with dementia complicated by depression, as compared to demented patients without affective symptoms and depressed patients without cognitive impairment. Results indicated that demented and demented/depressed groups had poorer discrimination abilities than the depressed group. Discrimination abilities of the demented and the demented/depressed groups were similar. Pattern of responses, however, reflected a significantly more conservative response bias in the demented/depressed group as compared to the demented group. The demented/depressed group were also more conservative than the depressed group, but this comparison did not reach statistical significance. These results suggest that the combined effects of dementia and depression have a "conservatizing" effect on response bias in demented/depressed patients. This "conservatizing" effect may provide useful information when considering if an underlying depression exists in a demented patient.



Depression in old age, Memory in old age, Older people, Mental health