A dissociation in the relation between memory tasks and frontal lobe tests in the normal elderly.

In this study a group of elderly subjects were examined on three tests of frontal lobe function. Two of these tests, FAS word fluency and the Alternate Uses Test, were considered tests of spontaneous flexibility, as defined by Eslinger and Grattan [Neuropsychologia 31, 17-28, 1993]. The third, the modified Wisconsin Card Sorting Test (WCST), is considered a test of reactive flexibility. Performance on two tests of memory, release from proactive interference (PI) and a matched recall and recognition test was also measured. The elderly were shown to be impaired on all tests when compared with young controls. Analysis revealed that release from proactive interference was significantly correlated with performance on alternative uses but not WCST while the size of subjects' discrepancy between recall and recognition correlated strongly with WCST but not with Alternate Uses. In addition there was a strong correlation between the two measures of spontaneous flexibility but these measures did not correlate with WCST. Performance on the two measures of memory was also uncorrelated. The data indicate that the pattern of frontal deterioration in the elderly does not comprise a single deficit and, furthermore, that the relationship between frontal dysfunction and normal age-related memory loss is not unidimensional.