EEGs during wake and sleep were performed on 420 patients without evidence of organic brain disease, with each decade represented up to and including the 70's. The distribution of the major frequency of the background rhythm shows a shift of the peak from 9 c/sec to 10 c/sec from the first to the second decade, then a flattening of this peak in the next two decades, an increase in the slower alpha frequencies in the 60's and a significant loss of the higher frequencies in the 70's when the major peak shifts back to 9 c/sec. Hyperventilation changes gradually decreased with age; delta patterns rapidly decreased after the first decade, theta activity gradually decreased, and focal slowing as maintained at approximately 20% at all ages, except for the first decade when no such focal changes were seen. The peak incidence of photic driving responses occurred during the 40's with a lower incidence during both the younger, but especially during the older age groups. Positive EEG findings include a gradual increase in sharp waves with age, except for a definite peak in the 40's. Slow waves also increased with age but show an abrupt increase in the 70's, mainly from slowing judged mild to moderate in degree, involving the frontal, temporal and occipital areas. These EEG findings were discussed with reference to other relevant studies and provide a base-line for judging abnormality in routine EEGs on patients with suspected organic brain disease.
|Original language||English (US)|
|Number of pages||9|
|Journal||Electroencephalography and Clinical Neurophysiology|
|State||Published - Jan 1 1977|
ASJC Scopus subject areas
- Clinical Neurology