Spatial working memory in Alzheimer's disease: A study using the Corsi block-tapping test.

The Corsi block-tapping test was developed as a non-verbal task to measure spatial memory. In this test, cubes are tapped by the examiner in novel sequences of increasing length after which participants are required to reproduce each sequence immediately.

Objectives: To evaluate spatial working memory in Alzheimer's disease (AD) patients.

Methods: 30 elderly control subjects (21 women, 9 men) and 30 patients with probable Alzheimer's disease (15 women and 15 men), with 8 or more years of schooling, were evaluated with the Mini-Mental State Examination (MMSE), digit span and Corsi block-tapping test. Proportions were compared using Chi-Square, and continuous variables with the Mann-Whitney tests.

Results: AD patients were older than controls (p=0.014), but there were no differences regarding gender or educational level between these groups. The performance on the Corsi block-tapping test differed between AD and control individuals (p=0.010), and between patients with moderate dementia and controls (p=0.032), but not between control individuals and patients with mild dementia (p=0.090).

Conclusions: In the present study, AD patients with moderate dementia showed impairment in spatial working memory while those with mild dementia did not. This finding may be due to the relatively small sample size, but it is also possible that spatial memory may be normal in the initial (limbic) phase of AD.