Measures of brain and hippocampal volume in 40 healthy young (aged 18–30 years) and 36 healthy elderly (aged 60–83 years) subjects were compared with composite cognitive function scores in three conceptual domains: memory ability, processing speed, and general fluid intelligence. Through a series of general linear models testing the relationship between these brain measures and cognitive performance scores, a significant positive relationship between hippocampal volume and fluid intelligence ability was found in elderly subjects but not in young. No relationship between the other cognitive domains and brain or hippocampal volume was found. The findings suggest a role of hippocampal atrophy in the decline in fluid intelligence in the elderly. (JINS, 2011, 17, 000–000)

Cognitive reserve is a hypothetical construct that has been used to inform models of cognitive aging and is presumed to be indicative of life experiences that may mitigate the effects of brain pathology. The purpose of this study was to evaluate the construct validity of cognitive reserve by examining both its convergent and its discriminant validity across three different samples of participants using structural equation modeling. The cognitive reserve variables were found to correlate highly with one another (thereby providing evidence of convergent validity), but demanding tests of discriminant validity indicated that, in two of the samples, the cognitive reserve construct was highly related to an executive functioning construct. (JINS, 2009, 15, 558–569.)