Differential episodic and semantic memory performance in Alzheimer's disease and vascular dementias

Differential performance on measures of episodic and semantic memory were examined in AD, cortical vascular dementia (CVaD), subcortica] vascular dementia (SVaD), and controls. Groups were matched on age, education, and gender; dementia groups also were matched on severity. Recognition/retrieval differences were found only between SVaD and AD groups, not between CVaD and AD. Thus, recognition/retrieval differences are likely secondary to subcortical pathology rather than to vascular etiology per se. Similarly, significant numbers of memory errors were associated with cortical pathology, regardless of etiology. Error rate differences were found only between SVaD and AD groups, not between CVaD and AD. Finally, rapid forgetting was unique to AD; however, since no difference was found between SVaD and AD, rapid forgetting may occur only as AD progresses. No semantic memory measure differentiated AD from either CVaD or SVaD subjects. Results suggest that some previously reported episodic differences may be due to cortical versus white matter subcortical pathology, rather than to AD versus vascular etiology.