A quantitative EEG analysis of the effects of baclofen on man

Abstract

The therapeutic potential of aminoacid derivatives has been recognized because of the important role aminoacides play in neurotransmission. Among the aminoacids derivatives tested in clinic, beta (parachlorophe-nyl)- gamma amino butyric acid (baclofen) a GABA derivative has proved to be very useful. The present investigation has been directed to estimate to what extent this drug is active at the brain level. Since normal volunteers given psychoactive substances would, to a certain extent, exhibit the same range of behavioural and physiological effects observed in the patient's population (Fink 1977) and in order to avoid the complexity of discriminating among the many drugs used in psychotic patients, non psychotic, male volunteers, in patients of age range 36–69 years were selected. These patients presented a long period of mild alcohol abuse without major complication, and exhibiting normal physical and laboratory findings.

All patients showed a predominant symptom of mild depression. The investigation began after the patients had been deprived of alcohol for at least 4 weeks. No medicine was given during the 2 weeks prior to the beginning of the study. The daily amount of baclofen given was 30 mg divided in 3 doses. One of the participants selected also received placebo in a double blind trial. The Brief Psychiatric Rating Scale (BPRS) and Standardized Hamilton Interview for Depression (SHID) were used together with routine progress notes for clinical evaluation.

EEGs were recorded prior to drug treatment as well as after 2,5, 12, 19 days of treatment and 2 days following the end of the treatment. A control EEG was also taken one week later. Routine visual assessment and automatic analysis completed by multivariant statistics of EEG spectral values were performed.

The changes of the power content in individual frequency bands were expressed in term of computerized EEG profiles. Furthermore, the whole EEG frequency pattern in each patient was compared with those obtained in normal subjects of different ages. The hypothetical age calculated from the EEG spectral measures could then be related to the actual age of the patient. A ratio between both ages has been proved to be a reliable indicator of EEG normality or abnormality.