Deterioration of frontal lobe function in normal aging: influences of fluid intelligence versus perceptual speed.

A group of young participants were compared with 2 groups of older participants (young-old, 65-74 years and old-old, 75 years or over) on a range of frontal lobe tasks. They were also assessed on the Digit Symbol Substitution Test (DSST), a test of digit cancellation (DC), the AH4 test of fluid intelligence, and the National Adult Reading Test (NART)-a measure of crystalized intelligence. Reliable age differences on all frontal measures except word fluency (FAS) were found.