The impact of the native language of Alzheimer's disease and normal elderly individuals on their ability to recall digits

Recent studies have indicated that Spanish-speaking Alzheimer's disease (AD) patients perform more poorly than English-speaking patients on the Digit Span subtests of the Wechsler Adult Intelligence Scale-Revised (WAIS-R). In the current investigation, the performance of English-speaking and Spanish-speaking Alzheimer's disease patients (N = 119) and normal elderly controls (N = 91) were compared with regards to their capacity to remember digit strings of different lengths. Subjects were administered the standard version of the Digit Span subtest of the WAIS-R as well as a modification of the test (chunking task) in which the numbers were presented in pairs (e.g. 27, 41, 46, 12, etc.). Results indicated that both English-speaking groups, AD patients as well as normal controls, had significantly higher scores on all aspects of the standard Digit Span tasks relative to their Spanish-speaking counterparts (forward, backward, and total scores). In contrast, English-speaking and Spanish-speaking AD groups did not differ with regards to their performance on the two digit chunking task forward score. Similar performance on all aspects of the chunking task was evidenced in the English-speaking and Spanish-speaking normal elderly control groups. These findings have important implications for the development of more culture and language appropriate cognitive test batteries for AD patients and the normal elderly.