A comparison of semantic memory in vascular dementia and dementia of Alzheimer's type

Abstract

Objective: To determine whether semantic memory is impaired in vascular dementia and to assess the utility of semantic memory measures in differentiating vascular dementia from dementia of Alzheimer's type (DAT).

Design: Case-control study.

Patients: Ten patients with Cambridge Mental Disorders in the Elderly (CAMDEX) diagnosis of 'definite' mild or moderate vascular dementia (mean age 77) were individually matched with 10 patients with a CAMDEX diagnosis of 'definite' DAT on the basis of age, education, sex, premorbid IQ (as measured by the National Adult Reading Test) and performance on the Cambridge Cognitive Examination (CAMCOG). In addition, 10 age, sex and education matched volunteer or relative controls were assessed.

Outcome measures: A detailed semantic memory test battery consisting of five subtests: category fluency, picture naming, picture sorting, word-picture matching and generation of verbal definitions.

Results: Compared to normal controls, both patient groups were impaired on all subtests of the semantic battery with the exception of the word-picture matching test. No differences were found between the vascular dementia and DAT groups on any of the measures.

Conclusions: Impairment of semantic memory is a feature of both vascular dementia and DAT. Tests of semantic memory appear, therefore, of little value in differentiating between these two major causes of dementia. Further work is required to determine whether the nature of the processing deficit is the same in these conditions.