Doctoral Degrees (Psychiatry)

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Browsing Doctoral Degrees (Psychiatry) by browse.metadata.advisor "Du Plessis, Stefan"

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    The impact of cannabis and methamphetamine use on clinical and functional aspects of outcome in first-episode Schizophrenia patients : a longitudinal study
    (Stellenbosch : Stellenbosch University, 2021-12) Scheffler, Frederika; Emsley, Robin (Psychiatrist); Du Plessis, Stefan; Kilian, Sanja; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Psychiatry.
    ENGLISH SUMMARY : Schizophrenia spectrum disorders, which schizophrenia, schizophreniform, and schizoaffective are severe and disabling disorders by a range of symptoms that psychosis, apathy and withdrawal, mood and impairment. "ness, hereafter referred to as schizophrenia spectrum or SSD, often starts to manifest during adolescence or early adulthood, and may have a lifelong This negative impact already conferred by schizophrenia spectrum disorders is further by a high rate of comorbid substance use. Despite high rate of comorbid substance abuse in schizophrenia spectrum disorders in South Africa, this population has remained under-researched in our setting. Specifically, cannabis and methamphetamine are two most commonly elicit substances in the Western Cape. Although there is literature on the role of cannabis and in the context of SSD, a number of questions as yet remain unanswered. Addressing such questions is necessary, especially in the South African context as resources for mental health are limited. The primary objective of this study was to investigate the impact of cannabis and methamphetamine use on baseline symptom severity and brain structure, and on clinical outcomes over 24 months of treatment with a long-lasting injectable antipsychotic in patients with a Schizophrenia spectrum disorder. Based on the nature of our cohort, as well as recent developments in the literature, we focussed specifically on the effects of cannabis and methamphetamines, as the two most used illicit substances in our region, and because of the availability of good data on these substances. We hypothesised that firstly, use is associated with poor psychopathology outcomes and higher relapse rates in first-episode schizophrenia spectrum disorder patients for whom treatment adherence is assured (objective I); cannabis methamphetamine have independent, and dose- time-dependant effects on cognitive functioning in first-episode schizophrenia spectrum disorder patients (objective II); cannabis use is with pre-treatment hippocampal volume reductions in first-episode schizophrenia patients compared to matched controls (objective III); First-episode schizophrenia spectrum disorder patients who use cannabis are at risk for treatment-emergent metabolic syndrome changes (objective IV). Regarding the selection of brain structural regions, we choose the hippocampal subfields, based on the recent development of software to accurately measure the subfields, together with an emerging literature on the relevance of the hippocampus in substance abuse. Specifically, this project investigated differences between First-Episode Schizophrenia Spectrum Disorder patients with and without cannabis and/or methamphetamine use in terms of relapse rates, psychopathology, functionality and quality of life, cognitive function, body mass and metabolic changes, and pre-treatment volumes. This sample consisted of 126 patients with a schizophrenia spectrum disorder and 100 healthy controls were similar in age, sex, and educational attainment. Each sub-study reported on in the present dissertation included a subset of the larger sample based upon the inclusion and exclusion criteria for each sub-study. First, regarding treatment response, we found little evidence for an effect of cannabis use on clinical improvement over 24 months in schizophrenia spectrum disorder patients. That being said, relapse events were more common in cannabis users compared to their non-using counterparts. Our findings point to an important role for non-adherence in previously reported poorer treatment outcomes in cannabis users, and a direct effect for cannabis in reducing the relapse threshold. Second, we found that methamphetamine use, but not cannabis use, was associated with poorer cognitive performance over the treatment period. Third, we found differential illness-specific associations with cannabis use and hippocampal subfield volumes, specifically subiculum volumes in cannabis using first-episode SSD patients. And lastly, compared to non-users, first-episode SSO patients who used cannabis gained less weight and showed less deterioration of lipid pones during the treatment period. Both cannabis and methamphetamine influence outcome over first two years of treatment in first-episode spectrum disorders. Some of our findings were contrary to our expectations have become foundation for future projects. In conclusion, our study highlights the benefits of the use of long-acting injectable antipsychotics for first-episode schizophrenia disorders, perhaps particularly in individuals who are currently using substances.