Influence of cognitive reserve on neuropsychologic functioning in Alzheimer's disease type sporadic in subjects of Spanish nationality

Objective: To evaluate the influence of cognitive reserve or brain reserve capacity on neuropsychologic performance in Spanish patients with Sporadic Late Onset Alzheimer Disease. Background: The three authors of this paper are professors who teach in psychology departments in different Spanish universities of recognized prestige. Methods: The sample used in this study comprised 97 subjects divided into two groups: one of 51 subjects diagnosed with Sporadic Late Onset Alzheimer Disease and another of 46 subjects who, with no family history of dementia at the time of examination, showed no type of neurologic or psychiatric disorder, nor did they have any record of alcoholism or drug-addiction. The evaluation of each subject in the clinical group consisted of a full neurologic examination, a neuropsychologic evaluation with a battery of tests designed for this study, and an assessment of mood with the Beck Depression Inventory. Cognitive reserve scores were based on a combination of years of education, a measure of occupational attainment, and an estimate of premorbid intelligence. Empirically derived factor scores and clinical summary ratings summarized performance on a battery of neuropsychologic tests. Results: The subjects with Alzheimer's disease with low cognitive reserve scores exhibited significantly greater deficits in measures of memory, attention language, executive functioning, and visuospatial performance than did the subjects with Alzheimer's disease with high cognitive reserve. Early neuropsychologic impairments in Alzheimer's disease are most evident in individuals with lower cognitive reserve. Conclusions: Our results reveal that patients diagnosed with Alzheimer's disease who have a high cognitive reserve attain a higher neuropsychologic performance than those with a low reserve. These results support the theory on the important protective role of education as well as that of certain occupational aspects (such as mental and cognitive demands from one's usual work) in the incidence of cognitive deterioration and dementia. These factors would increase cognitive reserve by requiring greater and more efficient communicative capacity from subjects as would participation in complex tasks that require the setting in motion of cognitive resources and capabilities.