OBJECTIVE: This study was designed to evaluate the relation between
intelligence and a variety of measures of brain structure. METHOD: Magnetic
resonance imaging scans were used to measure the volume of the intracranial
cavity, cerebral hemispheres, lateral ventricles, temporal lobes,
hippocampus, caudate, and cerebellum, as well as the overall volume of gray
matter, white matter, and CSF, in 67 healthy, normal volunteers.
Intelligence was measured with the Wechsler Adult Intelligence
Scale--Revised. RESULTS: Full-scale IQ was found to be significantly
correlated with intracranial, cerebral, temporal lobe, hippocampal, and
cerebellar volume but not with caudate and lateral ventricle volume. There
were also significant correlations of full- scale, verbal, and performance
IQ with overall gray matter volume but not with white matter or CSF volume.
Gender differences were noted in the pattern and number of correlations
between the volume of the brain and its subregions and full-scale, verbal,
and performance IQ. CONCLUSIONS: The results suggest that the size of some
cerebral structures may account for a significant, but modest, proportion
of the variance in human intelligence.