An EEG component differed in methamphetamine-dependent participants without psychosis history, while reaction times and error rates showed no significant group differences. The finding does not establish a diagnostic EEG test for methamphetamine-associated psychosis.
Huang and colleagues recruited 31 healthy controls, 14 methamphetamine-dependent participants without psychosis history and 24 with a history of methamphetamine-associated psychosis. One participant in the nonpsychosis group was excluded because of EEG data quality, leaving 13 in that group for analysis. Participants performed an addiction Stroop task involving drug-related and neutral words during scalp EEG recording.
Drug-related words elicited a more negative N200 amplitude over left-anterior electrodes in the nonpsychosis group compared with controls. The authors did not find the same pattern in the psychosis-history group. Other measured components, P300 and N450, did not show significant amplitude differences, and component latencies were also nonsignificant.
There were no significant group differences in reaction time or error rate. Thus, the EEG result cannot be reported as demonstrated slowing or poorer accuracy on the task. Associations between N200 amplitude and selected impulsivity ratings were observed in the small nonpsychosis subgroup, supplying a hypothesis about attentional processing rather than a universal marker of methamphetamine effects.
This was an observational human comparison during abstinence, not an experiment inducing psychosis or administering methamphetamine. Small and unequal subgroups limit precision, especially for within-group correlations. A significant comparison with controls in one group and a nonsignificant comparison in another does not itself prove a reliable diagnostic separation between the two clinical groups. No sensitivity or specificity threshold was validated for classifying an individual’s psychosis history. EEG measures time-linked electrical activity; it does not establish drug concentration, current intoxication or the cause of a particular real-world action.
See the separation between neural signals and behavioral performance for a complementary study.