Hippocampal atrophy relates to fluid intelligence decline in the elderly.

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.