Subcortical grey matter alterations in cocaine dependent individuals with substance-induced psychosis compared to non-psychotic cocaine users

After prolonged psychostimulant abuse, transient psychotic symptoms referred to as “substance-induced psychosis” (SIP) can develop - closely resembling symptoms observed in schizophrenia spectrum disorders. The comparability in psychotic presentation between SIP and schizophrenias suggests that similar underlying neural deficits may contribute to the expression of psychosis across these disorders. To date, neuroanatomical characterization of grey matter structural alterations in SIP has been limited to methamphetamine associated psychosis, with no studies controlling for potential neurotoxic effects of the psychostimulant that precipitates psychosis. To investigate grey matter subcortical alterations in SIP, a voxel-based analysis of magnetic resonance images (MRI) was performed between a group of 74 cocaine dependent nonpsychotic individuals and a group of 29 individuals with cocaine-associated psychosis. The cocaine-associated psychosis group had significantly smaller volumes of the thalamus and left hippocampus, controlling for age, total brain volume, current methamphetamine dependence, and current marijuana dependence. No differences were present in bilateral caudate structures. The findings of reduced thalamic and hippocampal volumes agree with previous reports in the schizophrenia literature, suggesting alterations of these structures are not specific to schizophrenia, but may be common to multiple forms of psychosis.