Centre for Youth Mental Health - Research Publications

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Author: McGorry, Patrick × Start date: 2012 × End date: 2012 ×

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    The Impact of Cannabis Use on Cognitive Functioning in Patients With Schizophrenia: A Meta-analysis of Existing Findings and New Data in a First-Episode Sample
    Yuecel, M ; Bora, E ; Lubman, DI ; Solowij, N ; Brewer, WJ ; Cotton, SM ; Conus, P ; Takagi, MJ ; Fornito, A ; Wood, SJ ; McGorry, PD ; Pantelis, C (OXFORD UNIV PRESS, 2012-03)
    Cannabis use is highly prevalent among people with schizophrenia, and coupled with impaired cognition, is thought to heighten the risk of illness onset. However, while heavy cannabis use has been associated with cognitive deficits in long-term users, studies among patients with schizophrenia have been contradictory. This article consists of 2 studies. In Study I, a meta-analysis of 10 studies comprising 572 patients with established schizophrenia (with and without comorbid cannabis use) was conducted. Patients with a history of cannabis use were found to have superior neuropsychological functioning. This finding was largely driven by studies that included patients with a lifetime history of cannabis use rather than current or recent use. In Study II, we examined the neuropsychological performance of 85 patients with first-episode psychosis (FEP) and 43 healthy nonusing controls. Relative to controls, FEP patients with a history of cannabis use (FEP + CANN; n = 59) displayed only selective neuropsychological impairments while those without a history (FEP - CANN; n = 26) displayed generalized deficits. When directly compared, FEP + CANN patients performed better on tests of visual memory, working memory, and executive functioning. Patients with early onset cannabis use had less neuropsychological impairment than patients with later onset use. Together, these findings suggest that patients with schizophrenia or FEP with a history of cannabis use have superior neuropsychological functioning compared with nonusing patients. This association between better cognitive performance and cannabis use in schizophrenia may be driven by a subgroup of "neurocognitively less impaired" patients, who only developed psychosis after a relatively early initiation into cannabis use.
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    Risk factors for relapse following treatment for first episode psychosis: A systematic review and meta-analysis of longitudinal studies
    Alvarez-Jimenez, M ; Priede, A ; Hetrick, SE ; Bendall, S ; Killackey, E ; Parker, AG ; McGorry, PD ; Gleeson, JF (ELSEVIER, 2012-08)
    BACKGROUND: Preventing relapse is an essential element of early intervention in psychosis, but relevant risk factors and precise relapse rates remain to be clarified. The aim of this study was to systematically compile and analyse risk factors for and rates of relapse in the early course of psychosis. METHODS: Systematic review and meta-analysis of English and non-English language, peer-reviewed, longitudinal studies, with a minimum 12-month follow-up and at least 80% of participants diagnosed with a first episode of psychosis (FEP) that reported risk factors for relapse. RESULTS: Of 153 potentially relevant articles, 29 were included in the study. Pooled prevalence of relapse of positive symptoms was 28% (range=12-47%), 43% (35-54%), 54% (40-63%) at 1, 1.5-2, and 3 years follow-up, in that order. A total of 109 predictors were analysed, with 24 being assessed in at least 3 studies. Of those, 20 predictors could be extracted for meta-analysis. Medication non-adherence, persistent substance use disorder, carers' critical comments (but not overall expressed emotion) and poorer premorbid adjustment, increased the risk for relapse 4-fold, 3-fold, 2.3-fold and 2.2-fold, respectively. CONCLUSIONS: Clinical variables and general demographic variables have little impact on relapse rates. Conversely, non-adherence with medication, persistent substance use disorder, carers' criticism and poorer premorbid adjustment significantly increase the risk for relapse in FEP. Future studies need to address the methodological limitations of the extant research (e.g. definition of relapse), focus on the identification of protective factors and evaluate theoretically derived models of relapse.
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    Phenylthiocarbamide (PTC) perception in ultra-high risk for psychosis participants who develop schizophrenia: Testing the evidence for an endophenotypic marker
    Brewer, WJ ; Lin, A ; Moberg, PJ ; Smutzer, G ; Nelson, B ; Yung, AR ; Pantelis, C ; McGorry, PD ; Turetsky, BI ; Wood, SJ (ELSEVIER IRELAND LTD, 2012-08-30)
    Reports suggesting that schizophrenia participants are more likely to be phenylthiocarbamide (PTC) non-tasters when compared to controls have recently been controversial. If supported, a genetic-based phenotypic variation in PTC taster status is implicated, suggesting a greater illness risk for those participants with recessive alleles for the TAS2R38 receptor. Should PTC insensitivity be a schizophrenia endophenotype, then it would be expected in follow-up of ultra high-risk for psychosis participants who later develop schizophrenia (UHR-S). UHR-S was hypothesised to show reduced PTC sensitivity compared to those who were previously at risk, but did not transition (UHR-NP). PTC perception was assessed in 219 UHR participants at long-term follow-up, of whom 53 had transitioned to psychosis (UHR-P) during the follow-up period. Fifteen of the 219 participants were diagnosed with schizophrenia. Seventy-eight had a family history of psychotic disorder. No differences in PTC taster status were found in UHR participants based upon transition to psychosis status, schizophrenia diagnosis, or family history of schizophrenia. This report indicates that schizophrenia development among UHR participants is not associated with PTC tasting deficits and fails to support previous findings that inability to detect the bitter taste of PTC is a schizophrenia endophenotype.