Age- and Dementia-Associated Impairments in Divided Attention: Psychological Constructs, Animal Models, and Underlying Neuronal Mechanisms

Abstract

Following a brief description of the psychological construct ‘divided attention’, impairments in divided attention and related executive functions are discussed as the major variable in the development and manifestation of age- and dementia-associated cognitive impairments. Neuropsychological and functional imaging studies in humans have indicated that dorsolateral and ventrolateral prefrontal, cingulate, parietal and premotor cortical areas are involved in the mediation of dual task performance. Furthermore, reduced activity in these areas has been suggested to mediate age- and dementia-associated impairments in divided attention. Experimental studies in animals have provided strong support for the hypothesis that cholinergic projections terminating in all cortical areas and layers crucially mediate the performance in tasks that tax processing capacity and/or the allocation of processing resources to competing demands. This specification of the ‘cholinergic hypothesis’ is evaluated in light of recent critical accounts of the role of this system in the development of age- and dementia- related cognitive disorders. The converging animal experimental and human neuropathological, as well as neuropsychological, evidence indicates that decreases in the integrity of cortical cholinergic inputs represent a necessary, possibly even sufficient, neuronal process mediating the impairments in divided attention and the resulting, broad decline in cognitive functions.

Reduction in hippocampal cholinergic innervation is unrelated to recognition memory impairment in aged rhesus monkeys

“…In addition, a study of cholinergic lesions in marmosets demonstrated that, when hippocampal inputs alone are interrupted, monkeys could perform simple visual discriminations but not conditional visuospatial discriminations (Ridley et al, 1999). Recent data also suggest that the cholinergic system and performance of prefrontal cortexassociated executive functions may be one locus of interaction (reviewed in Robbins, 2000;Sarter and Turchi, 2002), and further studies are necessary to dissociate the role of cortical versus hippocampal cholinergic input on relational memory. Viewed together, these results suggest that cholinergic input to the hippocampus plays a significant modulatory role on complex hippocampal information processing.…”

Where attention falls: Increased risk of falls from the converging impact of cortical cholinergic and midbrain dopamine loss on striatal function

“…Impairments in the ability to divide attention, as typically assessed by dual task performance, are generally correlated with chronological age (Crossley and Hiscock, 1992; Salthouse et al, 1995; for review see Sarter and Turchi, 2002). This main effect of age is typically interpreted as reflecting a decrease in the overall capacity for information processing or a decline in the executive management of such resources (Craik et al, 2010; Tombu and Jolicæeur, 2003).…”

The Influence of Short-term Strength Training on Health-related Quality of Life and Executive Cognitive Function

“…Impairment of executive function results in difficulties with activities of daily living, such as making a meal that might involve sequentially and flexibly washing, cutting, and boiling food (Carlson et al, 1999). Executive function is known to decrease with age (Cepeda et al, 2001;Verhaeghen and Cerella, 2002), and most dementia patients (Dishman et al, 2006;Sarter and Turchi, 2002) show impaired executive function. In recent years, physical exercise has been considered to contribute to the prevention of decrease in executive function in the elderly Kramer et al, 2003;McAuley et al, 2004).…”