ABSTRACT
Majority of the opioid-dependence and withdrawal studies are dominated with many inconsistencies and contradictions. One of the reasons for such inconsistencies may be methodological while performing EEG analysis. To overcome methodological limitations, in the present study we examined the composition of electroencephalographic (EEG) brain oscillations in broad frequency band (0.5-30 Hz) in 13 withdrawal opioid-dependent patients and 14 healthy subjects during resting condition (closed eyes). The exact compositions of brain oscillations and their temporal behaviour were assessed by the probability-classification analysis of short-term EEG spectral patterns (SPs). It was reported that early withdrawal had a generalized effect: the activity in all EEG channels was affected nearly equally. EEG of withdrawal patients was characterized by (a) different dominant SP types (had unique SP types which describe beta-frequency band), (b) increased number of SP types observed in each EEG channel, (c) a larger percentage of alpha(2)-, beta- and poly-rhythmic activity, and by a smaller percentage of delta-, - and alpha(1)-rhythmic activity, (d) predominantly right-sided asymmetry and (e) longer periods of temporal stabilization for alpha- and beta-brain oscillations and by shorter periods of temporal stabilization for -activity when compared with control subjects. When taken together, these findings suggest a considerable reorganization of composition of brain oscillations, which reflects a disorganization process and an allostatic state with neuronal activation in EEG of opioid withdrawal patients.