For the purpose of determining psychotropic properties of antiparkinsonian substances, the author has carried out a quantitative analytic study on EEG changes induced by six marketed antiparkinsonian drugs in young normal volunteers. The drugs were six antiparkinsonian agents, l-dopa (LDP) 100 mg, trihexyphenidyl (THP) 2 mg, 4 mg, biperiden (BPD) 1 mg, 2 mg, 5 mg, mazaticol (MZC) 4 mg, 8 mg, amantadine (AMD) 100 mg, bromocriptine (BMC) 1.25 mg, 2.5 mg, and amitriptyline (ATP) 25 mg, haloperidol (HPD) 3 mg, diazepam (DZP) 3 mg, inert placebo (PLB) as active and inactive controls. They were orally given to six healthy male volunteers respectively with two weeks interval and pre-drug, one, three, six hour post-drug EEGs were recorded and analyzed using our computer system with the periodgram technique. Placebo-controlled differences between pre- and post-drug EEGs were statistically treated with the principal component analysis. THP, BPD and MZC produced a marked decrease of alpha frequency associated with increases of slow and fast activities. In addition, MZC induced a slight delirious state with visual and auditory hallucinations at 8 mg in five of six subjects. EEG profiles of these drugs appeared very close to those of thymoleptics but the clinical observations suggest some psychodysleptic property of MZC at a higher dose. LDP provoked a decrease of lower alpha frequency and an increase of lower fast activity that may suggest central stimulant or mood elevating effects. BMC and AMD induced a decrease of slow activity associated with increases of higher alpha activity and lower fast activity in EEG and suggested their vigilance enhancing effects. Based on the current experience, it would be appropriate to use six EEG bands classification (delta, theta, lower alpha, higher alpha, lower beta, higher beta) instead of the fundamental four bands (delta, theta, alpha and beta) in pharmaco-EEG, as far as multivariate analysis of psychotropic drug profile is concerned. It must be noted that the higher part of alpha frequency present a completely different response from the lower part to the centrally effective drugs. Furthermore, psychiatrists should be as prudent as possible when prescribing antiparkinsonian drugs for prevention and treatment of drug induced extrapyramidalism.
