Fronto-temporal alterations and affect regulation in methamphetamine dependence with and without a history of psychosis

Methamphetamine (MA) has been shown to have neurotoxic effects associated with brain structure changes and schizophrenia-like psychotic symptoms. Although these abnormalities may in turn be related to cognitive impairment and increased aggression, their association with affect dysregulation is less well studied. We investigated cortical thickness and subcortical volumes in 21 participants with MA dependence, 19 patients with MA-associated psychosis (MAP), and 19 healthy controls. Participants' affect regulation abilities were assessed through self-report scales on emotion reactivity (ERS) and difficulties in emotion regulation (DERS) and correlated with differences in cortical thickness. MAP patients showed thinner cortices in the fusiform and inferior temporal gyrus (ITG), orbitofrontal (OFC) and inferior frontal gyrus (IFG), and insula, compared to the MA group. MAP also showed significantly lower hippocampal volumes relative to MA and CTRL. Both clinical groups showed impairment in affect regulation, but only in MAP was this dysfunction associated with thinner cortices in ITG, OFC and IFG. Our findings suggest significant differences in cortical thickness in MA dependence with and without psychosis. Lower fronto-temporal cortical thickness and smaller hippocampal volumes in MAP are consistent with neuroimaging findings in other psychotic disorders, supporting the notion of MAP being a useful model of psychosis.