Neuropsychological performance in Alzheimer's disease and vascular dementia: comparisons in a memory clinic population

Objectives: To compare the performances of two matched groups of patients with Alzheimer's disease (AD) and vascular dementia (VaD) on a battery of neuropsychological tests.

Methods: 325 patients attending a memory clinic were given a detailed multi-disciplinary diagnostic assessment, including a battery of neuropsychological tests administered by a psychologist and a speech and language therapist. The performances of two groups of patients meeting ICD-10 criteria for AD (n = 103) and VaD (n = 68) were compared, adjusting for age, gender, dementia severity and pre-morbid IQ. Patients with co-morbid depression and mixed AD+VaD were excluded.

Results: After adjustment, the AD and VaD groups differed significantly on the Graded Naming Test (VaD superior), AMIPB Complex Design immediate and delayed recall (VaD superior), the Trail Making Test error score (Part B) (VaD superior), and Verbal Picture Description (VaD superior).

Conclusions: These findings support previous evidence that language function and non-verbal memory are selectively more impaired in AD. The better performance by VaD patients on the Trail Making Test (B) runs counter to previous suggestions that there is an excess of frontal executive dysfunction in this disorder. It may be that this test is more sensitive to the early impairment of concurrent manipulation of information in AD.