Neuropsychological performance in Lewy body dementia and Alzheimer's disease

Background Lewy body dementia(LBD) is emerging as a common cause of degenerative dementia. However, LED cannot yet be diagnosed with certainty in life. There is some preliminary evidence that the pattern of cognitive impairment in LED is different from that in Alzheimer's disease (AD). We set out to compare the performance on different subtests of the Cambridge Cognitive Examination (CAMCOG) of LBD patients and AD patients who were similar in overall degree of cognitive impairment. Methods All patients were recruited from a memory clinic. LED (n=17)was diagnosed according to the MeKeith clinical criteria. AD (n=17)was diagnosed according to NINCDS-ADRDA criteria. The performances of LED and AD patients on the neuropsychological subscales of the CAMCOG were compared by applying Hotelling's multivariate test of significance and subsequent univariate F tests. Results There were no statistically significant differences between the two groups on Mini-Mental State Examination and global CAMCOG rating. Hotelling's test with LED and AD as the between-group factor and the neuropsychological subtests from CAMCOG as dependent variables revealed a statistically significant group effect (P < 0.05). Univariate F tests showed that recall (P < 0.02) and praxis (P < 0.003) significantly contributed to this effect. Conclusions These results suggest that there may be different neuropsychological profiles in the two conditions, with IBD subjects being better on recall but worse on praxis than those with AD.