Attention and CERAD test performances in cognitively impaired elderly subjects

Attention plays a fundamental role in cognitive performance and is closely interrelated with all major cognitive domains. In this retrospective study, we correlated different measures of attention with standard cognitive parameters in 85 cognitively impaired elderly individuals presenting with cognitive complaints to a memory clinic.

Z-scores of all relevant cognitive parameters of a extended Consortium to Establish a Registry for Alzheimer's disease (CERAD-Plus) neuropsychological battery were correlated with tonic and phasic alertness, inhibition, and divided attention, assessed by a computerized test battery of attention. The pooled sample consisted of 36 patients with the diagnosis of mild AD, 30 patients with mild cognitive impairment, and 19 patients with major depressive disorder.

Subjects of all diagnostic groups exhibited normal results in all subtests of attention. Reaction times of neither the tonic nor the phasic alertness task were correlated with any parameter of memory and global cognition. However, significant correlations were obtained between reaction times in the alertness tasks and the trail-making tests. Omissions in the divided attention task yielded the strongest correlations with deficits in cognitive performance, particularly in the verbal learning tasks, the Boston naming test, and the trail-making tests.

Our data demonstrate the relative independency of the CERAD-Plus on the variability of attention and particularly alertness suggesting its robustness in psychiatric memory clinic settings. Moreover, CERAD-Plus subtests correlated considerably with failure rates in divided attention, suggesting that impairment in divided attention tasks may be early markers of cognitive impairment.