G. N. Smith

University of British Columbia - Vancouver, Vancouver, British Columbia, Canada

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Publications (33)137.5 Total impact

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    ABSTRACT: Reduced cortical gray-matter volume is commonly observed in patients with psychosis. Cortical volume is a composite measure that includes surface area, thickness and gyrification. These three indices show distinct maturational patterns and may be differentially affected by early adverse events. The study goal was to determine the impact of two distinct obstetrical complications (OCs) on cortical morphology. A detailed birth history and MRI scans were obtained for 36 patients with first-episode psychosis and 16 healthy volunteers. Perinatal hypoxia and slow fetal growth were associated with cortical volume (Cohen's d = 0.76 and d = 0.89, respectively) in patients. However, the pattern of associations differed across the three components of cortical volume. Both hypoxia and fetal growth were associated with cortical surface area (d = 0.88 and d = 0.72, respectively), neither of these two OCs was related to cortical thickness, and hypoxia but not fetal growth was associated with gyrification (d = 0.85). No significant associations were found within the control sample. Cortical dysmorphology was associated with OCs. The use of a global measure of cortical morphology or a global measure of OCs obscured important relationships between these measures. Gyrification is complete before 2 years and its strong relationship with hypoxia suggests an early disruption to brain development. Cortical thickness matures later and, consistent with previous research, we found no association between thickness and OCs. Finally, cortical surface area is largely complete by puberty and the present results suggest that events during childhood do not fully compensate for the effects of early disruptive events.
    Psychological Medicine 12/2014; FirstView:1-13. DOI:10.1017/S003329171400292X · 5.94 Impact Factor
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    European Archives of Psychiatry and Clinical Neuroscience 10/2013; · 3.53 Impact Factor
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    ABSTRACT: Fibers connecting fronto-temporal and fronto-medial structures that pass through the anterior limb of the internal capsule (ALIC) subserve executive and psychomotor functioning. Both of these functions are adversely affected in schizophrenia, and may be abnormal at illness onset. In a study of first-episode psychosis, we used diffusion tensor imaging (DTI) and cognitive testing to examine ALIC integrity. Fourteen early psychosis patients and 29 healthy volunteers were included. Symptoms were assessed with the Positive and Negative Syndromes Scale (PANSS). All structural and diffusion scans were acquired on a GE Signa 1.5T scanner. A T1-weighted 3D FSPGR Inversion Recovery imaging series was acquired for manual seeding in structural space. Diffusion tensor imaging (DTI) was performed, and all DTI images were co-registered to structural space. Seeds were manually drawn bilaterally on the coronal plane at a specified location. Diffusion images were post-processed for subsequent Tract-based Spatial Statistics (TBSS) analysis. First-episode psychosis patients had significantly smaller fronto-medial and fronto-temporal AIC tract volumes compared to healthy volunteers on the left and the right (p-values<0.04). No differences in mean fractional anisotropy (FA) were seen within either left or right tracts (p-values>0.05), nor did TBSS reveal any other differences in FA values between groups in other regions. Relationships between tract volumes and symptom severity were not observed in this study.
    Schizophrenia Research 08/2012; 141(1):29-34. DOI:10.1016/j.schres.2012.06.042 · 3.92 Impact Factor
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    ABSTRACT: Abnormalities in connectivity are thought to contribute to the symptoms of schizophrenia. Accumulating evidence suggests that antipsychotic medication affects both subcortical and cortical grey and white matter volumes. The goal of this study was to investigate the effects of antipsychotic medication on two white matter tracts: a subcortical-cortical tract, the anterior and posterior limbs of the internal capsule; and a cortical-cortical tract, the corpus callosum. Magnetic resonance imaging was conducted on 10 chronic schizophrenia patients treated with typical antipsychotics and 20 healthy controls at baseline. Patients were switched to olanzapine and both groups were rescanned after 1 year. At baseline, the volume of the anterior limb of the internal capsule was 24% smaller in typical-treated patients than controls (p = 0.009). Patients treated with greater amounts of chlorpromazine-equivalent daily dosage had smaller anterior internal capsule volumes at baseline (r = -0.65, p = 0.04). At follow-up, after being switched to olanzapine, there were no significant differences between patients and controls. Patients with schizophrenia had a significant 25% increase in anterior internal capsule volume from baseline to follow-up compared with controls (p = 0.04). These effects were most prominent in the anterior limb of the internal capsule, which consists of fronto-thalamic pathways, and were not statistically significant in the posterior limb of the internal capsule or corpus callosum. Olanzapine may be effective in normalizing fronto-thalamic structural connectivity in schizophrenia.
    Journal of Psychopharmacology 04/2010; 25(5):621-9. DOI:10.1177/0269881110363314 · 3.59 Impact Factor
  • G.N. Smith · J Boydell · R.M. Murray · S Flynn · K McKay · M Sherwood · W.G. Honer ·
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    ABSTRACT: The risk for schizophrenia in immigrants to Europe is approximately three times that of native-born populations. Discrimination and marginalization may influence the risk for schizophrenia within migrant populations. The primary objective of the present study was to determine whether the risk associated with migration was also evident 100 years ago. A second objective was to determine whether changing social stresses are associated with changes to the incidence of schizophrenia. During the first two decades of the twentieth century, the Provincial Mental Hospital was the sole provider of psychiatric services in British Columbia, Canada. Detailed clinical records have been preserved for 99.5% of 2477 patients who had a psychiatric admission between 1902 and 1913. Diagnoses were made after a detailed file review and 807 patients met DSM-IV criteria for first-episode schizophrenia, schizophreniform disorder, schizoaffective disorder, or psychosis not otherwise specified. Diagnoses had high inter-rater reliability. The incidence of schizophrenia in migrants from Britain or Continental Europe was compared with that in the Canadian-born population using indirect standardization and Poisson models. Migration from Britain or Continental Europe to Canada in the early twentieth century was associated with an increased rate of schizophrenia; IRR=1.54, (95% CI=1.33-1.78). Incidence increased over time in immigrants but not in the native-born population and this increase occurred during a period of economic recession. Migration was a risk factor for schizophrenia a century ago as it is today. This risk occurred in white migrants from Europe and increased during a period of increased social stress.
    Schizophrenia Research 11/2006; 87(1-3):205-11. DOI:10.1016/j.schres.2006.06.024 · 3.92 Impact Factor
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    ABSTRACT: The thalamus is the gateway for sensory and motor information en route to the cortex. Information is processed via thalamocortical and corticothalamic pathways coursing through the internal capsules. In this study, we investigated the relationship between the anterior limb of the internal capsule, posterior limb of the internal capsule, and thalamus in first-episode psychosis (FEP). Twenty-nine FEP subjects (26 DSM-IV schizophrenia, 2 schizoaffective disorder, 1 psychosis not otherwise specified) and 22 healthy volunteers participated in this study. Anterior limb of the internal capsule (AIC), posterior limb of the internal capsule (PIC), and the thalamus volumes were manually determined from MRI scans. FEP subjects had reduced AIC volumes (F(1,45)=6.18, p=0.017) and thalamic volumes (F(1,45)=8.00, p=0.007) compared to healthy volunteers. PIC volumes did not differ. Significant correlations between AIC volumes and thalamic volumes were observed in subjects with FEP, but not in healthy volunteers. Negative relationships between thalamic volumes and symptom severity were also observed. The AIC and thalamic volumes were reduced in subjects with FEP compared to healthy volunteers. Abnormalities in thalamocortical and orticothalamic pathways may contribute to functional disruption of neural circuits in psychosis.
    Schizophrenia Research 11/2006; 87(1-3):89-99. DOI:10.1016/j.schres.2006.05.002 · 3.92 Impact Factor
  • T.S. Ehmann · I Khanbhai · G.W. MacEwan · G.N. Smith · W.G. Honer · S Flynn · S Altman ·
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    ABSTRACT: Factor analytic studies of the Positive and Negative Syndrome Scale (PANSS) have consistently isolated a factor that is frequently labeled as 'cognitive'. The present study sought to further explore the factor by examining the relationships between 4 versions of the cognitive factor and a set of neuropsychological tests. Thirty-seven inpatients diagnosed with schizophrenia or schizoaffective disorder were assessed with the PANSS and neuropsychological measures. Verbal intelligence and verbal memory were found to be most closely associated with cognitive factor scores. A global rating of illness severity showed greater relationships to cognitive variables than any cognitive factor. The PANSS cognitive factor may reflect verbal ability and memory, but is not sufficiently comprehensive to be considered as a replacement for direct assessment of cognitive functioning.
    Psychopathology 10/2004; 37(5):253-8. DOI:10.1159/000081022 · 2.08 Impact Factor
  • T S Ehmann · T Kragelj · G N Smith · E Higgs · S W Flynn · S Altman · G W MacEwan · W G Honer ·
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    ABSTRACT: The assessment of outcomes after treatment with antipsychotic medication is fundamental to clinical care and research. The Routine Assessment of Patient Progress (RAPP) is a reliable multidimensional scale that employs nurses' ratings of symptoms and functioning in psychiatric inpatients. The present study sought to extend validity evidence for the RAPP by examining its ability to reflect changes associated with treatment by antipsychotic medications. The use of a different sample in this study also provided the opportunity to replicate earlier validity data collected on the original set of patients. Ninety-seven separate trials were conducted, involving 65 consecutive admissions to a unit that specializes in the assessment and treatment of patients with long standing severe psychiatric disorders. The RAPP, along with the Positive and Negative Syndrome Scale and global measures of severity, were administered at baseline and at the end of each trial. Both factor scores and clinically-derived subscales were analysed for sensitivity to change. Patients were globally rated as improved, unchanged or worsened at the end of the medication trial. Results indicated that the RAPP factor, clinical scale and total scores compared favourably to other outcome measures in patients rated as improved or worse. In patients rated as unchanged, RAPP scores displayed significantly less change than did the PANSS scores. These findings support the validity of the RAPP as an outcome measure in treatment trials.
    Journal of Psychopharmacology 01/2004; 17(4):425-9. DOI:10.1177/0269881103174006 · 3.59 Impact Factor
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    ABSTRACT: Schizophrenia unfolds during the late period of brain maturation, while myelination is still continuing. In the present study, we used MRI and T2 relaxation analysis to measure the myelin water fraction in schizophrenia. In schizophrenia (n=30) compared with healthy subjects (n=27), overall white matter showed 12% lower myelin water fraction (P=0.031), with the most prominent effects on the left genu of the corpus callosum (36% lower, P=0.002). The left anterior genu was affected in both first-episode (P=0.035) and chronic patients (P=0.011). In healthy subjects, myelin water fraction in total white matter and in frontal white matter increased with age, and with years of education, indicating ongoing maturation. In patients with schizophrenia, neither relation was statistically significant. Post-mortem studies of anterior frontal cortex demonstrated less immunoreactivity of two oligodendrocyte-associated proteins in schizophrenia (2',3'-cyclic nucleotide 3'-phosphodiesterase by 33%, P=0.05; myelin-associated glycoprotein by 27%, P=0.14). Impaired myelination in schizophrenia could contribute to abnormalities of neural connectivity and persistent functional impairment in the illness.
    Molecular Psychiatry 10/2003; 8(9):811-20. DOI:10.1038/sj.mp.4001337 · 14.50 Impact Factor

  • Schizophrenia Research 03/2003; 60(1):198-199. DOI:10.1016/S0920-9964(03)81124-6 · 3.92 Impact Factor
  • G. N. Smith · L. Lupton · W. G. Honer ·

    Schizophrenia Research 03/2003; 60(1):50-50. DOI:10.1016/S0920-9964(03)80149-4 · 3.92 Impact Factor

  • Schizophrenia Research 03/2003; 60(1):200-200. DOI:10.1016/S0920-9964(03)81129-5 · 3.92 Impact Factor
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    ABSTRACT: The areas of function affected by major mental disorders are more diverse than the list of core symptoms assessed by many psychiatric rating scales, and the cross-sectional picture obtained in mental status interviews often fails to capture important data. Information on patient function can be obtained from measures that are based on extended observation and complement symptom-focused assessments. The Routine Assessment of Patient Progress (RAPP) is a 21-item rating scale that assesses both functional and psychiatric symptoms. It is usually completed by nursing staff who have observed patients over a 1-week period. Previous research has shown it to be reliable, valid, simple to complete, and of substantial value for patient care and diagnosis. The present study sought to examine the psychometric structure of the RAPP to define what domains of symptoms and behavior it measures. RAPP scores obtained from 165 psychotic inpatients were submitted to a factor analysis. A five-factor solution was derived in which 18 of 21 RAPP items were assigned to factors. The factors were labeled aggression, positive symptoms, negative symptoms, somatization/anxiety, and organic/ disorganization. The RAPP factors were moderately correlated with conceptually similar factor scores derived from the Positive and Negative Syndrome Scale (PANSS). RAPP aggression scores were validated with an independent clinical measure of aggression. Patients who were independently rated as improved over their hospital stay showed significant improvement on all RAPP factors, and unimproved patients showed stability or deterioration on RAPP measures. The data indicate that RAPP factors assess domains of psychopathology that are moderately correlated with both global ratings and symptom-focused scales. The RAPP's sensitivity to change suggests it is a valid measure of treatment outcome that could be used in controlled trials, as well as standard care outcome evaluation.
    Comprehensive Psychiatry 01/2001; 42(1):32-8. DOI:10.1053/comp.2001.16557 · 2.25 Impact Factor

  • European Neuropsychopharmacology 09/2000; 10:306-306. DOI:10.1016/S0924-977X(00)80350-8 · 4.37 Impact Factor

  • Schizophrenia Research 01/2000; 41(1):127-127. DOI:10.1016/S0920-9964(00)90610-8 · 3.92 Impact Factor
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    ABSTRACT: Substantial variability in age at onset of illness and course of illness exists between patients with schizophrenia. Recent studies suggest that age at illness onset may be useful in defining biologically and clinically distinct subgroups of patients. Two hundred and ten males with schizophrenia were classified as early-onset or adult-onset according to their age at first hospitalization. Birth history, clinical functioning and treatment response was assessed in a subgroup of patients. Brain anatomy was assessed from CT scans in all patients and in 32 non-psychiatric control subjects. Patients with an early-onset were likely to have a history of obstetric complications, a poor response to neuroleptic treatment, and showed no relationship between ventricle size and duration of illness. Adult-onset patients were less likely to have obstetric complications, more likely to respond to treatment in the first years of illness, and showed an association between brain structure and duration of illness. The distinction between early- and adult-onset patients may have important aetiological and treatment implications.
    Psychological Medicine 06/1998; 28(3):645-53. DOI:10.1017/S0033291797006405 · 5.94 Impact Factor
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    ABSTRACT: Clozapine and risperidone are used in treatment-resistant schizophrenia. At present, there are few reported comparisons of these drugs in this population. We report on a consecutive series of treatment-resistant schizophrenics given either clozapine or risperidone in open clinical trials. Subjects were treated with clozapine (n = 57) or risperidone (n = 29). Pretreatment GAF, CGI, and PANSS scores did not differ between the groups, nor did demographic variables including age, age at first hospitalization, years ill, number of previous hospitalizations, or gender. The mean treatment trial was 12.1 weeks, with mean doses of clozapine 420 mg, and risperidone 7.75 mg. The length of the trial did not differ significantly between the groups. Response was taken to be a 20% decrease in the PANSS score. Using repeated measures ANOVA, PANSS total scores (F = 5.3, p = 0.02) and positive subscore (F = 7.4, p = 0.008) showed greater improvement in the clozapine group than the risperidone group, while other PANSS subscores showed a trend toward greater improvement with clozapine. The PANSS-derived factors of excitement (F = 6.7, p = 0.01), psychosocial withdrawal (F = 3.8, p = 0.05), and psychomotor retardation (F = 3.9, p = 0.05) improved more in the group treated with clozapine. The GAF (F = 10.9, p = 0.0014), CGI (F = 11.5, p = 0.0011), and CGI improvement (p = 0.0001) scores also improved more in the clozapine group. Of the clozapine group, 25 (44%) responded, while 8 (28%) of the risperidone group responded to treatment. Clozapine had better efficacy in subjects with treatment-resistant schizophrenia compared to risperidone, although risperidone appears to yield better response rates than those previously reported for typical antipsychotics. Double-blind, controlled trials of risperidone are needed to establish its efficacy in treatment-resistant schizophrenia.
    Pharmacopsychiatry 02/1998; 31(1):25-9. DOI:10.1055/s-2007-979291 · 1.85 Impact Factor

  • Schizophrenia Research 01/1998; 29(1). DOI:10.1016/S0920-9964(97)88717-8 · 3.92 Impact Factor

  • Schizophrenia Research 12/1997; 29(1):17-17. DOI:10.1016/S0920-9964(97)88330-2 · 3.92 Impact Factor

  • Schizophrenia Research 12/1997; 29(1):16-17. DOI:10.1016/S0920-9964(97)88328-4 · 3.92 Impact Factor