61 The Impact of Cognitive Reserve on Executive Function in Dementia

Abstract

Objective:Cognitive reserve (CR) refers to how flexibly and efficiently the individual makes use of available brain resources. Early-life education, midlife social and occupational activities, and later-life cognitive and social interactions are associated with greater CR. Years of education, premorbid intellectual (IQ) functioning, linguistic ability, and occupational complexity are often used as proxies of CR. CR theory seeks to explain discrepancies between the extent of disease pathology and clinical presentation amongst individuals with dementia. In the presence of Alzheimer’s Disease (AD) pathology, higher CR is associated with slower declines in executive functioning (EF). The current study examined the correlation between CR and EF performance across various stages of dementia severity as measured by the total score on the Clinical Dementia Rating Scale (CDRS).Participants and Methods:The study cohort consisted of 269 individuals who had completed measures of EF and the CDRS from phase 1 of the Alzheimer’s Disease Neuroimaging Initiative (ADNI). Individuals who scored less than 2 on the CDRS were included in the MCI group (n=197), while individuals that scored 2 or higher on the CDRS were included in the dementia group (n=73). A simple linear regression was utilized to compare the MCI group to dementia group across CR and EF performance.Results:There was significant correlation between CR and EF performance in the MCI group as quantified on total CDRS score (F (200) = .353, p = .0, p < .05). CR was not observed to be predictive of EF in the dementia group (F (200) = .031, p = .666, p > .05).Conclusions:Findings are consistent with prior research suggesting CR is protective during early stages of dementia, but not in the later disease stages. As prior research has shown the expression of dementia is based on a complex interaction between genetic and lifestyle factors that are unique to each person, future research exploring the potentially protective role of CR amongst pre-symptomatic adults with a genetic predisposition for developing dementia may expand our understanding of the potential role of CR on dementia prevention and progression.