UBC Theses and Dissertations
Investigation into the symptom severity and neuroanatomy of stimulant-induced psychosis in a marginalized population Alexander, Peter
Psychosis is expressed in many mental disorders and often varies in the way symptoms are presented. Two forms that have similar psychotic profiles are schizophrenia spectrum disorders (SZ) and stimulant induced psychosis (SIP). The similar profiles suggest a common mechanism involved in the development of psychosis, and the pattern of symptoms expressed in SIP and SZ. There are limited studies on the severity of psychotic symptoms in SIP and the associated drug involved. Few studies have compared brain connectivity and structural abnormalities associate with SIP and SZ. Attempting to shed light on the underlying mechanisms involved in the expression of psychosis in SIP, two studies were performed; 1) compare symptom severity of SIP between cocaine and methamphetamine dependent individuals, and 2) compare brain alterations between idiopathic psychosis and SIP individuals with and without stimulant dependence. In study 1, symptom severity was analyzed using the three and five factor models of the positive and negative syndrome scale (PANSS) between a group of 153 cocaine dependent (CD), 38 methamphetamine dependent (MD), and 32 concurrent cocaine + methamphetamine dependent (CMD) subjects defined by DSM-IV-TR criteria. The MD group was associated with more severe positive symptoms on the PANSS. The CMD group did not have an increase in psychosis severity. To investigate brain abnormalities that may be involved in the positive symptom profile of SIP, study 2, a voxel-based grey matter region of interest (ROI) approach using magnetic resonance imaging (MRI) and whole brain diffusion tensor imaging (DTI) analysis was employed. Three groups of 39 SZ subjects with stimulant dependence (SZ-dependent), 39 SIP subjects with stimulant dependence (SIP-dependent), and 18 SZ subjects without stimulant dependence (SZ-nondependent) were compared. The voxel-based analysis observed SZ-dependent group presented with significantly reduced planum temporale and parietal operculum volumes compared to the SIP-dependent group. Using tract-based spatial statistics (TBSS) to assess white matter tracts, the SIP-dependent group had reduced fractional anisotropy and increased radial diffusivity compared to the SZ-dependent group. The results characterize the effects that different stimulant drugs have on symptom severity and the specific areas of the brain that potentially promote positive psychotic symptom profile of SIP.
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