Intelligence and brain structure in normal individuals.
OBJECTIVE
This study was designed to evaluate the relation between intelligence and a variety of measures of brain structure.


METHODS
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.
Andreasen
N C
NC
Mental Health Clinical Research Center, University of Iowa Hospitals and Clinics, Iowa City 52242.
Flaum
M
M
Swayze
V
V
O'Leary
D S
DS
Alliger
R
R
Cohen
G
G
Ehrhardt
J
J
Yuh
W T
WT
D001921:Brain / Q000033:anatomy & histology*; D002421:Caudate Nucleus / Q000033:anatomy & histology; D002531:Cerebellum / Q000033:anatomy & histology; D002540:Cerebral Cortex / Q000033:anatomy & histology; D002552:Cerebral Ventricles / Q000033:anatomy & histology; D005260:Female; D007839:Functional Laterality; D006624:Hippocampus / Q000033:anatomy & histology; D006801:Humans; D007360:Intelligence; D008279:Magnetic Resonance Imaging; D008297:Male; D012737:Sex Factors; D013702:Temporal Lobe / Q000033:anatomy & histology; D014888:Wechsler Scales