Cognitive deficits in the elderly: interactive theories and a study of environmental effects on psychometric intelligence.

Abstract

Problems related to psychometric measures of intelligence are discussed with regard to both the general characteristics and metric properties (validity, reliability and sensibility) of mental tests, and interindividual differences (cultural background, education, life contents and age-cohorts). Currently used standard intelligence tests explore the structure of intelligence only in part, so a distinction must be made between true actual intelligence, potential inheritance of intelligence, and psychometrical or scored intelligence. The correct use of intelligence testing, however, does provide some relevant and objective information regarding the evolution of cognitive structure during adulthood and in relationship to aging. Cognitive performance in the elderly follows a downward curve that is not explained as a result of aging on physiological responses (i.e., reaction time delay, signal-noise ratio in the CNS, degenerative loss of cortical cells, etc.). Biologically based theories of intelligence cannot explain the large individual differences in cognitive abilities observed in subjects who have very similar physical characteristics. Cognitive approaches to intelligence enable us to better understand the causal factors of the cognitive deficits in the elderly, and an interactive model permits us to fully integrate both the individual differences in cognitive abilities and the large consistency in performances. We compared the cognitive performances of two groups of elderly subjects, ranging in age from 65 to 97 years; we observed some statistically significant effects on cognitive deficit that could be explained as fully deriving from emotional and extra-cognitive responses to environmental changes.