Alzheimer's disease, depression and normal ageing: merit of simple psychomotor and visuospatial tasks

A brief psychometric test battery was used to differentiate Alzheimer's disease (AD) patients from patients with depression and healthy age-matched control subjects. The purpose was to investigate the discriminative value of simple psychomotor and visuospatial tasks that were implemented in a computer-assisted test battery.

Manumotoric coordination, discrimination reaction time and performance on a visuospatial pattern-matching task were assessed. Subjects were 30 patients with the diagnosis of probable AD (mild to moderate), 22 patients with a major depression and 15 healthy normal control subjects.

Discrimination reaction time separated the three groups most distinctly, but general level of cognitive functioning was a significantly confounding variable. There were no differences between the AD and the depressed patients when the MMSE was used as a covariate. Substantial deficiencies in manumotoric coordination were found in both demented and depressed patients. The visual pattern-matching task yielded longer reaction times in both patient groups than in the control group.

Translated into neuropsychological terms, these data suggest deficiencies in basic central operations, a slowing of central information processing and attentional deficits in AD and depressed patients. Psychomotor tasks were able to distinguish effectively healthy elderly persons from AD and depressed patients. This test battery, however, appears to be limited in differentiating AD from depression.