Alasdair Barr

Associate Professor

Relevant Degree Programs

Affiliations to Research Centres, Institutes & Clusters


Graduate Student Supervision

Doctoral Student Supervision (Jan 2008 - Nov 2020)
Acute cardiometabolic side effects of clozapine in rodents (2020)

No abstract available.

A preclinical evaluation of antipsychotic drug-induced metabolic side-effects: A focus on glucose dysregulation and insulin resistance (2013)

No abstract available.

Master's Student Supervision (2010 - 2018)
Antipsychotic prescribing patterns on admission to and discharge from a tertiary care program for treatment-resistant psychosis at Riverview Hospital (2017)

The treatment of psychosis typically requires the use of only one antipsychotic. Even in instances of treatment-resistant psychosis, the atypical antipsychotic clozapine has proven to be effective when used on its own. However, antipsychotic polypharmacy is commonly prescribed despite a lack of evidence for this practice. This concurrent use of two or more antipsychotics can also prolong the time before clozapine is tried. Antipsychotic polypharmacy should be reserved for instances of clozapine-resistant psychosis if it is to be used at all.In this retrospective study, data were collected from individuals who were referred to a tertiary care program for treatment-resistant psychosis. The main objectives were to compare the use of antipsychotic monotherapy to polypharmacy in treatment-resistant psychosis and to characterize within-individual changes in treatment and symptomatology secondary to hospitalization.At admission, individuals who were prescribed only one antipsychotic were comparable to those who were prescribed at least two antipsychotics with regard to demographics and symptom severity. The use of drugs other than antipsychotics was also similar between groups. However, the magnitude of antipsychotic utilization was greater in individuals who were receiving antipsychotic polypharmacy. In addition, a greater proportion of these individuals received excessive doses at admission. Similar findings were observed when monotherapy and polypharmacy were compared at discharge.Three important patterns were identified when investigating within-individual changes. First, fewer individuals were on polypharmacy at discharge. This was accompanied by a general decrease in both the number of antipsychotics prescribed and the magnitude of antipsychotic utilization. Second, the number of individuals who were prescribed clozapine had increased by discharge. Those who were already prescribed clozapine at admission typically had their doses increased. Third, improvements in symptomatology were observed across all of the subscales included in the Positive and Negative Syndrome Scale (PANSS). However, only 57.9% of individuals experienced a relative reduction in PANSS scores greater than 20%.Based on these findings, it is possible to alleviate the symptoms of psychosis in treatment-resistant psychosis while reducing antipsychotic utilization. Although this may seem counterintuitive, an increase in the use of clozapine and a decrease in antipsychotic polypharmacy may have contributed to clinical improvement.

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Neuroanatomical Correlates of Psychostimulant-Associated Psychosis (2016)

After prolonged psychostimulant abuse, some individuals develop transient psychotic symptoms referred to as “substance induced psychosis” (SIP), which closely resemble the symptoms observed in schizophrenia spectrum disorders. The comparability in psychotic presentation between SIP and the schizophrenias suggests that similar underlying neural deficits may contribute to the emergence of psychosis across these disorders. Anatomically, only a small number of studies have attempted to characterize the structural alterations in SIP – all of which solely focus on methamphetamine associated psychosis. To further characterize the nature of psychostimulant-associated psychosis, three investigations were performed to identify 1) gray matter abnormalities, 2) white matter abnormalities, and 3) environmental risk factors of current symptom severity in psychostimulant dependent individuals with and without a DSM-IV diagnosis of substance-induced psychosis. To investigate gray matter abnormalities in study 1, a voxel-based analysis of magnetic resonance images (MRI) was performed between a group of 74 cocaine dependent nonpsychotic (CDN) individuals and a group of 29 individuals with cocaine-associated psychosis (CAP). The CAP group had significantly smaller volumes of the thalamus and left hippocampus, controlling for age, total brain volume, current methamphetamine dependence, and current marijuana dependence.To investigate white matter abnormalities in study 2, diffusion tensor imaging was employed in a group of individuals with cocaine-associated psychosis (CAP; n=24) and a cocaine dependent nonpsychotic group (CDN; n=43). Tract based spatial statistics (TBSS) was used to investigate group-differences in white matter diffusion parameters. The cocaine-associated psychosis group showed significantly lower fractional anisotropy values than the cocaine dependent nonpsychotic group (p
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Delirium after transcatheter aortic valve implantation : a retrospective chart review of associated risk factors and outcomes (2011)

A retrospective chart review was performed to determine the incidence and risk factors of delirium after transfemoral and transapical transcatheter aortic valve implantation (TAVI), and open-heart aortic valve replacement (AVR) (n = 45 per group). A number of secondary outcomes were also compared between the surgeries, including 24-hour, 30-day, 1-year and 2-year mortality; time spent in intensive care; total length of hospitalization; need for emergency cardiopulmonary bypass during operation (for TAVI procedures only); and frequencies of postoperative complications. Delirium occurred significantly less frequently in transfemoral TAVI (16%) than in transapical TAVI (51%) or open-heart AVR (38%) (p
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