Resting-State Electroencephalographic Coherence in Recently Abstinent Methamphetamine Users

 Long-term use of Methamphetamine (MA) can impose some deficits by its toxicity on the brain structure and function. It can also alter brain electrical activity and cortico-cortical neural connections. The coherence index of electroencephalography reflects the temporal integration of electrical oscillations between different sites of the brain and could be affected by the chronic use of MA.

 In this study, we aimed to compare quantitative electroencephalography (QEEG) coherence as an index of brain connectivity between methamphetamine users and healthy people.

 In this descriptive-analytical study, 18 patients with methamphetamine abstinence and 18 healthy people with no history of psychiatric illness were evaluated. Electroencephalography was recorded during eyes-open and eyes-closed states for each group, and then, the analysis for coherence between different twin electrodes was performed. The evaluation was done on occipital, temporal, frontal, and parietal lobes. Repeated-measures ANOVA and t-test were conducted for statistical analysis (P < 0.05).

 Coherence differences in frontal, temporal, and occipital lobes were not significant while coherence was significantly different in parietal lobes between the groups (P = 0.03), so that a decrease in C3-CZ electrode coherence in both delta and theta bands in methamphetamine users was significant (P = 0.03 and P = 0.01, respectively).

 It was revealed that brain coherence could be changed after the chronic use of MA, especially in slow waves. This could be an indicator of structural and functional damage in the neuronal population and show less regional integration in cortical areas in MA users, possibly due to substance toxicity.