Electro-encephalography spectral analysis of heroin addicts compared with abstainers and normal controls

Previous studies have shown that opiates slow the EEG and, in high doses, reduce the threshold of seizure activity. The present work looks at computerized EEG analyses (in the Fast Fourier Transform-FFT-method) of heroin addicts, recent abstainers and normal controls, with the aim of comparison and delineation of group characteristics. Examinations of 60 taped EEG recordings were performed: 20 subjects were current heroin users, 20 were recent abstainers and 20 were normal controls. Statistical analysis was performed for the relative frequency of wave bands. To amplify the known findings of slowing in heroin users, specific ratios were calculated: the alpha ratio (namely, the 8.0-9.5 Hz to 9.5-12.0 Hz ratio) and the delta to low alpha ratio. The specificity and sensitivity of the FFT method were evaluated through the use of discriminant analysis. The EEG was also recorded on conventional paper and evaluated by a neurologist.

The addicts had a higher alpha ratio. The abstainers had a slowing of their alpha waves, a high incidence of delta waves and a delta to low alpha ratio that was relatively high. As a function of time from the beginning of abstinence, this ratio decreased. Abstainers for more than 80 days and controls had identical EEGs. The FFT method had 50% sensitivity for the addicts and 70% for the abstainers, while the specificity was 55%. In contrast, the neurologist's reading of the EEG had a very low sensitivity (25% for the addicts, 30% for the abstainers and 20% for the controls) and a 70% specificity.