[The profile of memory disturbance in early Lewy body dementia differs from that in Alzheimer's disease].

It may be difficult to distinguish Lewy body dementia (LBD) from Alzheimer's disease (AD) especially at an early stage. Clinical diagnostic criteria for LBD still lack sensitivity. We compared memory performance in early AD and LBD to identify features that may help to distinguish these two conditions. Patients with Mini Mental State scores equal or above 18 were consecutively selected retrospectively from the University Out-patient Memory Clinic database. Probable LBD and AD were respectively diagnosed according to the international consensus criteria and the NINCDS-ADRDA criteria. Short-term memory was assessed with the digit span subtest of the Wechsler Memory Scale and the Corsi block-tapping test. Long term verbal memory was assessed with a French version of the Grober and Buschke test. Long-term visual memory was tested with the recall of four geometric figures of the CERAD battery. There was no difference between the two groups in short-term or long-term visual memory. Except for the immediate and first free recalls, DCL patients performed significantly better than AD patients in all subtests of the Grober and Buschke test. The more striking differences were seen with the third total and delayed total recall. These results highlight the differences of memory impairment pattern in early LBD and AD. Episodic verbal memory is better in LBD patients who benefit more from cues, reflecting the subcortical component of the disease. Such neuropsychological data should be validated prospectively and further be part of the diagnostic criteria.