Cognitive reserve, age, and their relation to attentional and executive functions

The main objective of this research was to establish the relation between age, cognitive reserve (CR), and attentional and executive functions. One hundred and sixty healthy participants aged 20 to 65 years old completed a wide battery of frontal-lobe tasks using classical tests that assess planning and control of movement, problem solving, and inhibition of automatic response, visuomotor tracking, focused and sustained attention, shifting, spontaneity and reasoning. The total sum of the score in premorbid IQ (by means of the Weschsler Adult Intelligence Scale Vocabulary subtest), educational level, and type of profession was used as a proxy of CR. Subjects were divided into groups of low or high CR. Multiple linear and logistic analyses revealed that age is a predictor of the 20Q Test, Terman Merril's Picture task, Similarities, Digit Span (backward), Trail-Making Tests, Porteus Maze Trace, the "A" Letter Cancellation Test, and reciprocal inhibition. CR is a predictor of the Controlled Oral Word Association Test, Trail-Making Tests A and B, Digit Span (forward), and Similarities. In conclusion, a higher CR score is associated with better performance in almost all tests employed. But it has a significant contribution to performance on verbal fluency, behavioral spontaneity, reasoning, divided and complex attention, and working memory functions, which are mainly related to the dorsolateral prefrontal area.