Slower speed-of-processing of cognitive tasks is associated with presence of the apolipoprotein ε4 allele

Detection of preclinical cognitive deficits is important for identifying those at greatest risk for such disorders as Alzheimer’s disease. However, available neuropsychological measures may not be sufficiently sensitive to preclinical cognitive impairment, particularly in high functioning or younger older adults. This study utilizes a battery of computerized cognitive tests (Cognometer) designed to provide a more sensitive measure of age-related cognitive performance by incorporating speed-of-processing components. Fifty-one community-dwelling older adults were administered the Cognometer battery, which incorporates speed-of-processing components into measures of verbal, spatial and working memory, attention, and visuo-spatial ability. Performance of 18 subjects with the ε4 allele was compared to that of 33 subjects without the ε4 allele. A brief battery of standard neuropsychological measures was also administered. No significant differences were observed between the two groups with respect to performance on any of the neuropsychological measures. However, with respect to the Cognometer battery, individuals with the ε4 allele were significantly slower in performing all the cognitive tasks, with the exception of the visuo-spatial task. With respect to performance, the two genotype groups did not differ significantly except on immediate memory, with the ε4 group exhibiting increased errors. Overall, the ε4 group was significantly slower in performing all of the Cognometer memory tasks. These findings provide continued support for the negative impact of the ε4 allele on cognition and further suggest that speed-of-processing during memory tasks may have the potential to detect subtle cognitive deficits.