Subcortical volumes, frontal cortical thickness, and pro-inflammatory cytokines in schizophrenia versus methamphetamine-induced psychosis

Background Clinical features of schizophrenia and methamphetamine-induced psychosis (MAP) have significant overlap. Schizophrenia is associated with alterations in subcortical volumes, cortical thickness and pro-inflammatory cytokines that may correlate with clinical features. However, analogous work on MAP is lacking. This study compared subcortical volumes, cortical thickness and pro-inflammatory cytokines in individuals with schizophrenia, MAP, and healthy controls. It also assessed associations of neuroimaging measures and cytokine levels with each other, with illness duration and symptom severity in schizophrenia and MAP, and with duration of substance use in MAP. Methods Participants included 36 individuals with schizophrenia, 27 with MAP, and 32 healthy controls matched for age and sex. Diagnosis was determined using the Structured Clinical Interview for Axis I Disorders and symptom severity was assessed using the Positive and Negative Syndrome Scale. Structural T1-weighted images were acquired using a 3 Tesla magnetic resonance imaging scanner. Serum peripheral cytokine concentrations levels were measured using a multiplex bead array. Analysis of covariance was used to compare measures across groups. Results Individuals with schizophrenia and with MAP had decreased left amygdala volumes and frontal cortical thickness compared to healthy controls. Individuals with schizophrenia had increased volumes in bilateral caudate, putamen, and nucleus accumbens compared to healthy controls, and increased right globus pallidus and NAcc volumes compared to MAP. Individuals with MAP had increased right orbitofrontal cortical thickness compared to healthy controls. Decreased left amygdala volumes and frontal cortical thickness were significantly associated with longer illness duration in schizophrenia, and with longer duration of methamphetamine use in MAP. There was no significant difference across groups in cytokine levels, and no significant associations of cytokine levels with neuroimaging or clinical measures. Conclusion This study found overlaps and differences in the neurobiology of schizophrenia and MAP, a finding that is consistent with previous research. Further studies with larger sample sizes and more robust measures are needed to understand immune mechanisms underlying these conditions. ### Competing Interest Statement The authors have declared no competing interest.