Intelligence quotient-adjusted memory impairment is associated with abnormal single photon emission computed tomography perfusion.

Cognitive reserve among highly intelligent older individuals makes detection of early Alzheimer's disease (AD) difficult. We tested the hypothesis that mild memory impairment determined by IQ-adjusted norms is associated with single photon emission computed tomography (SPECT) perfusion abnormality at baseline and predictive of future decline. Twenty-three subjects with a Clinical Dementia Rating (CDR) score of 0, were reclassified after scores were adjusted for IQ into two groups, 10 as having mild memory impairments for ability (IQ-MI) and 13 as memory-normal (IQ-MN).

IQ-based norms for highly intelligent adults.

This study presents normative data of commonly used neuropsychological tests administered to 75 individuals with high levels of intelligence (estimated IQ > or = 120). Participants were living independently in the community with ages ranging from 44 to 86. To avoid including individuals with an incipient dementia, we selected subjects who scored within the normal range on all cognitive tests for at least a two-year period.