Quantitative EEG abnormalities in recently abstinent methamphetamine dependent individuals

Objective: Methamphetamine exposure is associated with long-lasting reductions in markers for dopaminergic neurons in preclinical models and probably in humans. Quantitative electroencephalography (EEG) has been used to characterize abnormalities in brain function in a number of disorders, including cocaine dependence, but this technique has not been used to characterize abnormalities associated with methamphetamine dependence. Methods: The sample included 11 methamphetamine dependent subjects and 11 non-drug using volunteers. Methamphetamine dependent subjects were hospitalized for 4 days to document abstinence; non-drug using volunteers were studied as outpatients. EEGs were recorded in the eyes-closed resting state, and absolute EEG power in each frequency band (0.5–4, 4–8, 8–12, and 12–20 Hz) was quantitated using a fast Fourier transform. EEG power was log-transformed prior to analysis. Conventional, EEG tracings were interpreted by a qualified electroencephalographer who was blinded to the subjectsʹ identity. Results: Methamphetamine dependent volunteers with 4 days of abstinence had increased EEG power in the delta and theta bands. Power in the alpha and beta bands did not differ between the groups. Within the methamphetamine dependent group, a majority of the conventional EEGs were abnormal (64%), compared to 18% in the non-methamphetamine using group. Conclusions: Recently abstinent methamphetamine dependent subjects demonstrate QEEG abnormalities that are consistent with a generalized encephalopathy. Significance: Encephalopathic changes in brain electrical activity, as found here in methamphetamine dependence, are frequently associated with a range of cognitive and psychiatric abnormalities, suggesting further avenues of investigation.