Relation of EEG alpha background to cognitive function, brain atrophy, and cerebral metabolism in Down's syndrome. Age-specific changes
O. Devinsky, S. Sato, R. A. Conwit and M. B. Schapiro
EEG Laboratory, National Institute of Neurological Disorders and Stroke, Bethesda, Md. 20892.
We studied 19 young adults (19 to 37 years old) and 9 older patients (42 to
66 years old) with Down's syndrome (DS) and a control group of 13 healthy
adults (22 to 38 years old) to investigate the relation of
electroencephalographic (EEG) alpha background to cognitive function and
cerebral metabolism. Four of the older patients with DS had a history of
mental deterioration, disorientation, and memory loss and were demented.
Patients and control subjects had EEGs, psychometric testing, quantitative
computed tomography, and positron emission tomography with fludeoxyglucose
F 18. A "blinded" reader classified the EEGs into two groups--those with
normal alpha background or those with abnormal background. All the control
subjects, the 13 young adult patients with DS, and the 5 older patients
with DS had normal EEG backgrounds. In comparison with the age-matched
patients with DS with normal alpha background, older patients with DS with
decreased alpha background had dementia, fewer visuospatial skills,
decreased attention span, larger third ventricles, and a global decrease in
cerebral glucose utilization with parietal hypometabolism. In the young
patients with DS, the EEG background did not correlate with psychometric or
positron emission tomographic findings, but the third ventricles were
significantly larger in those with abnormal EEG background. The young
patients with DS, with or without normal EEG background, had positron
emission tomographic findings similar to those of the control subjects. The
mechanism underlying the abnormal EEG background may be the neuropathologic
changes of Alzheimer's disease in older patients with DS and may be
cerebral immaturity in younger patients with DS.
