The Broad Importance of Cognitive Impairments in Aging-Related Disorders

This series of interesting and important studies focuses on the importance of cognitive functioning in the elderly, across a variety of different neuropsychiatric conditions. These articles examine the importance of cognitive factors in the risk for older individuals in the development of disruptive behavior disorders 1 and suicide attempts, 2 as well as the genetic susceptibility factors for cognitive changes associated with anticholinergic exposure 3 and changes in patterns of cortical activity associated with cognitive demands in cases with identified mild to moderate dementia. 4 Consistent with considerable research on individuals with identified neuropsychiatric conditions, cognitive impairment leads to dysfunction in the ability to perform everyday living skills. 5 Clearly evident in all of these articles is the substantial importance of cognitive impairments in late life adjustment. As important, however, is the indication that not all cognitive impairments are the same. Global cognitive ability is repeatedly found to not be a potent predictor of these highly specific and different elements of outcome. Impaired functioning in executive abilities is consistently found to be more strongly related than general cognitive deficits to later disruptive behaviors, functional disability, and risk for suicide. Further evidence for the importance of this brain system in the elderly is presented by Hermann et al. 4 , who associated reduced prefrontal regional activity with poor performance on a measure of verbal fluency. One of the important findings of the current set of articles is that the assessment of impaired executive ability in the elderly can be accomplished with high validity with clinical rating scales, as well as performance-based measures. The convergence of these findings across different assessment methods and populations underscores the importance of regular assessment of executive abilities in older individuals in whom there is any suspicion of cognitive changes. These impairments seem to be predictive of the risk for later cognitive and functional changes, which may have multiple implications for intervention planning to avert negative impacts from these changes as well. The fact that executive functioning impairments predict risk for suicide attempts, functional disability, and disruptive behavior means that such an assessment may have substantial importance for subsequent treatment planning. Another of the articles in this issue reveals the highly interesting finding that genotypic variation predicts vulnerability to the adverse cognitive effects of anticholinergic medications. The APOE-4 gene is already well understood to relate to the risk for Alzheimer disease and for cardiovascular risk factors. What the findings of Pomara et al. 3 suggest is not only scientifically important—that the effects of variation in this gene may have a direct impact on the cholinergic system— but also that this gene may influence cholinergic sensitivity in the otherwise healthy older individuals. This is a particularly important issue in the general medical treatment of the elderly, where excessive cholinergic burden leads to cognitive changes and risk for delirium and falls. The findings of these studies suggest that cognitive functioning may be the key linkage between several apparently disparate outcomes in aging-related con