The results of a double-blind study evaluating the EEG and behavioral effects of chlorpromazine hydrochloride and dyphenhydramine hydrochloride on 29 children indicate that EEG findings alone can show whether or not a child is receiving medication. There was also a significant correlation between the more marked clinical behavior changes and the more marked EEG changes. The EEG effects of both drugs included slow alpha waves and generalized slowing, in the case of diphenhydramine hydrochloride, high voltage 4 to 6 cycle per second activity was uniformly produced by the relatively high doses used in this study.
Korein J, Fish B, Shapiro T, Gerner EW, Levidow L. EEG and Behavioral Effects of Drug Therapy in ChildrenChlorpromazine and Diphenhydramine. Arch Gen Psychiatry. 1971;24(6):552-563. doi:10.1001/archpsyc.1971.01750120068012