Do atypical antipsychotics really enhance smoking reduction more than typical ones?: the effects of antipsychotics on smoking reduction in patients with schizophrenia.

Whether atypical antipsychotics (AAs) can enhance smoking reduction in schizophrenic patients remains controversial because of methodological limitations in existing studies. This study explored whether certain types of antipsychotics predict smoking reduction in schizophrenic patients. Three hundred eight smoking, predominantly male schizophrenic patients (271/308 [88.9%]) participated in an 8-week open-label study with antismoking medications (high-dose, low-dose nicotine transdermal patch and bupropion). Antipsychotics were classified into (1) typical antipsychotics (TAs) and (2) AAs, including multiacting receptor-targeted antipsychotics (clozapine, olanzapine, and quetiapine), serotonin-dopamine antagonists (risperidone), D2/D3 receptor antagonists (amisulpride), and partial dopamine receptor agonists (aripiprazole). A general linear model was used to explore whether types of antipsychotic predict changes in the number of cigarettes smoked per day (CPD) and the score of the Fagerstrom Test for Nicotine Dependence (FTND) while controlling for confounding factors. The type of antipsychotic (TAs or AAs) was not significantly associated with smoking cessation (n = 21; χ = 1.8; df = 4; P = 0.77). Regarding smoking reduction, the type of antipsychotic was significantly predictive of a change in the CPD (P = 0.027; partial eta square = 0.055) and FTND scores (P = 0.002; partial eta square = 0.073). The 95% confidence intervals of the estimated means of change in the CPD and FTND scores did not contain zero only among subjects on TAs or clozapine.These findings suggest that TAs and clozapine enhance smoking reduction compared with nonclozapine atypical antipsychotics in schizophrenic patients. The mechanisms underlying the effects of various antipsychotics on smoking reduction remain unclear and warrant future study.

Decreased brain serotonin transporter binding in the euthymic state of bipolar I but not bipolar II disorder: a SPECT study.

OBJECTIVES: Previous positron emission tomography studies have demonstrated that serotonin transporter (SERT) binding in the midbrain is decreased in the depressive state of bipolar disorder (BD). The aim of this study was to assess SERT binding in the midbrain of patients in a euthymic state of BD. METHODS: Twenty-eight healthy controls and 24 patients in a euthymic state of medicated BD were recruited. Euthymic state was defined as Montgomery-Asberg Depression Rating Scale scores < 10 and Young Mania Rating Scale scores < 7 within a consecutive eight-week period. Single photon emission computed tomography with the radiotracer (123)I-ADAM was used to measure SERT binding in the midbrain. An equilibrium ratio model was used for data analysis. Specific uptake ratio (SUR), which represents availability of SERT binding in the midbrain, was the primary measurement outcome. RESULTS: The averaged SURs were not different between healthy controls and BD patients in euthymic state (p = 0.27). However, a three-way ANCOVA analysis comparing SURs in healthy controls, bipolar I disorder (BD I) patients, and bipolar II disorder (BD II) patients, covarying education duration and sex, showed that the averaged SURs were significantly lower in BD I than BD II patients and healthy controls (p = 0.042). The decreased SURs in BD I patients were well correlated with duration of illness (R = -0.742, p = 0.014) only. CONCLUSIONS: Our findings demonstrate that there is differential biological regulation in BD I and BD II patients after stable treatment, which may support the existence of a dichotomy in BD.

Effects of haloperidol and risperidone on cerebrohemodynamics in drug-naive schizophrenic patients.

BACKGROUND: Use of antipsychotics may be associated with cerebrovascular adverse events in psychotic patients. In this study, the effects of haloperidol and risperidone on the cerebral hemodynamics and the possible relationships between antipsychotics and cerebrovascular risks tendency were evaluated by Transcranial Doppler ultrasonography (TCD). METHODS: Twenty drug-nai ve schizophrenic patients and 20 normal control subjects were included. The patients were divided into haloperidol- and risperidone-treated groups and received treatment for 8 weeks double-blindly. The subjects' cerebral blood flow mean velocities (MV) and pulsatility index (PI) were measured weekly by TCD. The Positive and Negative Syndrome Scale for schizophrenia (PANSS) was used to assess the patients' psychopathological symptoms. RESULTS: Increased MV and decreased PI were found significantly in drug-nai ve schizophrenic patients than normal subjects before treatment (p<0.01). The decreased PI could be normalized after 8 weeks of antipsychotic treatment, while the increased MV could not. Treatment with haloperidol could significantly increase the PI than the treatment with risperidone (p<0.01) throughout the treatment course. The PANSS scores of both groups were significantly improved (p<0.05) at the endpoints of treatment. CONCLUSIONS: Our findings indicate that haloperidol may affect the cerebral hemodynamics in drug-naive schizophrenics more prominently than that of risperidone via TCD monitoring.

Association between frailty and its individual components with the risk of falls in patients with schizophrenia spectrum disorders.

Frailty is common among older people who carry an increased risk for poor outcomes, including falls, physical disabilities, infections, and mortality. However, the prevalence of frailty and the prognostic influence of frailty status are poorly understood in adults with schizophrenia. The present study aimed to assess the predictive ability of frailty and its individual components for the risk of falls in patients with chronic schizophrenia. Frailty status was assessed at baseline by using Fried frailty criteria after the enrollment of 561 patients with chronic schizophrenia. The patients were followed up for 18 months, and the outcome of the study was the incidence of falls. The mean age of the patients was 53.8 years, and a total of 35.3% were females. One-quarter (25.3%) of patients received typical antipsychotics. The prevalence of frailty was 10.2% at baseline. During follow-up, 40 patients (7.1%) experienced falls. Frailty status was associated with increased susceptibility to falling with an unadjusted hazard ratio of 5.27 (95% confidence interval: 2.75-10.10) and a hazard ratio of 4.65 (95% confidence interval: 1.88-11.54) after multivariate adjustment. Among the components of frailty, the most significant association was observed between low physical activity and falls (p < 0.05). In conclusion, frailty is highly prevalent in patients with chronic schizophrenia and is associated with the risk of adverse clinical events. Further studies are needed to explore the mechanisms underlying the relationship between schizophrenia and frailty in an attempt to develop an appropriate treatment plan for improving clinical outcomes for these patients.

The Alpha-2A Adrenergic Receptor Gene -1291C/G Single Nucleotide Polymorphism is Associated with the Efficacy of Methylphenidate in Treating Taiwanese Children and Adolescents with Attention-Deficit Hyperactivity Disorder.

OBJECTIVE: The therapeutic effect of methylphenidate (MPH) in treating attention-deficit/hyperactivity disorder (ADHD) has been related to the alpha-2A adrenergic receptor (ADRA2A) gene -1291C/G single nucleotide polymorphism (SNP). We investigated the effect of MPH in treating Taiwanese children and adolescent with ADHD and its relation to the ADRA2A gene -1291C/G SNP. METHODS: The subjects with DSM-IV ADHD diagnosis underwent a titration period to find out the dose of MPH for maintenance treatment. After 4 weeks maintenance treatment, the effect of MPH was evaluated by the Swanson, Nolan and Pelham version IV total scores. The subjects with more than 25% score reduction were referred to responders and those with ≥50% improvement were considered as better responders. The -1291C/G variant of the ADRA2A gene was identified by DNA sequencing and what relevance it has to the MPH response was examined by binary logistic regression analysis. RESULTS: Of the 59 subjects, 44 (74.6%) were responsive to MPH treatment and the responsiveness was not shown to be associated with the ADRA2A gene -1291C/G SNP. As the responsive subjects were categorized as moderate responders and better responders and subjected to statistical analysis, the GG homozygotes showed a greater chance to have a better response to MPH treatment than CC homozygotes (p=0.02), with an odds ratio of 32.14 (95% CI=1.64-627.80). CONCLUSION: The ADRA2A gene -1291C/G SNP is associated with the efficacy of MPH for the treatment of ADHD in Taiwanese children and adolescents. The responsive subjects bearing homozygous -1291G allele are more likely to have a better response to MPH treatment.

Effects of antipsychotics on cognitive performance in drug-naive schizophrenic patients.

It has been reported that antipsychotics may improve cognitive function in the treatment of schizophrenia. The present study examined the effect of haloperidol and risperidone on cognitive performance in schizophrenic patients. 95 healthy subjects and 68 schizophrenic patients were recruited for comparison of cognitive function. As 20 of the 68 schizophrenic patients were drug-naive, they were randomly divided into two groups and double-blinded for treatment with either haloperidol or risperidone for an 8-week period. Each subject received Wisconsin Card Sorting Test (WCST) and Maze paradigms for cognitive function performance. For schizophrenic patients, the Positive and Negative Syndrome Scale (PANSS) was used for evaluation of clinical symptoms. Results demonstrated that in both WCST and Maze paradigms the 68 schizophrenic patients had worse cognitive performance compared with healthy subjects. Of the 20 drug-naive schizophrenic patients from the 68 in-patients, both haloperidol and risperidone improved the clinical symptoms. Maze tasks performance was improved progressively after haloperidol and risperidone treatment, although improvement was greatest with risperidone. Both haloperidol and risperidone had no evident effect on WCST performance. Our findings suggest that Maze paradigms may be an ideal tool for evaluation of pharmacological treatment effects on cognitive function in schizophrenic patients. Furthermore, risperidone may have more treatment benefits than haloperidol on cognitive performance in drug-naive schizophrenic patients.

Cigarette smoking has a differential effect on the plasma level of clozapine in Taiwanese schizophrenic patients associated with the CYP1A2 gene -163A/C single nucleotide polymorphism.

OBJECTIVE: The efficacy of clozapine clearance has been shown to be associated with smoking and genetic polymorphism of CYP1A2. This study aims to investigate the effect of smoking on the plasma level of clozapine in Taiwanese schizophrenic patients and its relevance to the CYP1A2 gene -163A/C single nucleotide polymorphism. MATERIALS AND METHODS: A total of 143 hospitalized schizophrenic patients who had received clozapine therapy for at least 14 days were enrolled in this study. The trough plasma concentration of clozapine was measured with LC/MS/MS. The -163A/C variant in the CYP1A2 gene was identified by DNA sequencing and restriction fragment length polymorphism analysis. The effect of smoking on the clozapine level was examined by multiple linear regression analysis and its relation to the -163A/C variant of the CYP1A2 gene was analyzed using a general linear model with Bonferroni correction. RESULTS: Patients with smoking habits showed a significantly lower plasma level of clozapine than those without smoking habits (P=0.022) and the difference in clozapine levels between smokers and nonsmokers appeared to be significant in the individuals carrying the homozygous -163A allele (P=0.02). It was also found that nonsmokers carrying the -163A allele tended to have higher plasma levels of clozapine. This tendency was not found in the individuals with smoking habits. CONCLUSION: Cigarette smoking has a significant impact on the plasma level of clozapine in Taiwanese schizophrenic patients carrying the homozygous -163A allele in the CYP1A2 gene. Cigarette smoking may increase the clearance of clozapine in these patients.

Validation of a five-factor model of a Chinese Mandarin version of the Positive and Negative Syndrome Scale (CMV-PANSS) in a sample of 813 schizophrenia patients.

OBJECTIVES: The Positive and Negative Syndrome Scale (PANSS) is one of the most widely used instruments for measuring the severity of schizophrenia. However, until now, there has not been a published, validated Chinese Mandarin version of the five-factor model PANSS with confirmatory factor analysis (CFA) for schizophrenic patients in Taiwan. METHODS: A total of 813 subjects were recruited. Internal consistency was evaluated with Cronbach's alpha coefficient. For test re-test reliability, 57 patients were reassessed and intra-class correlation coefficients were calculated. For validity, exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) using a Structured Equation Model were implemented to identify the factor model. RESULTS: The Cronbach's alpha coefficient was 0.928. The intra-class coefficient was 0.878 (95% CI: 0.79-0.92). The final model was composed of five factors. EFA explained a total of 64.2% of the variance. CFA indicated a good fitting model. Except for the PANSS items G7 (motor retardation), G8 (uncooperativeness), N5 (abstract thinking), and G10 (disorientation), this study found that the items loaded on these factors were similar to the consensus items published in prior studies. CONCLUSIONS: In summary, these findings support the Chinese Mandarin version of the PANSS as a reliable and valid instrument for the assessment of the severity of psychopathology in hospitalized, stable patients with schizophrenia. More effective and specific treatment models targeting sub-culture differences are expected to be developed in future studies.

Estrogen supplementation for female schizophrenics treated with atypical antipsychotics.

It has been suggested that estrogen supplementation can augment the treatment effects of typical antipsychotic medication. We report the use of estrogen supplementation for four female chronic inpatients. These patients were diagnosed with schizophrenia or schizoaffective disorders and were treated with atypical antipsychotics. Premenstrual exacerbation of psychiatric symptoms had been noted for all patients. Daily oral conjugated estrogen (Premarin 0.625 mg) was administered for three months continuously, and patients were assessed using the Nurses' Observation Scale for Inpatient Evaluation. Attenuation of premenstrual aggravation of psychiatric symptoms during menstruation was noted for two of the four cases, with substantial improvement noted for one of these. After Premarin treatment was discontinued, three patients were assessed as worse than the pre-supplementation phase using the evaluation scale. This finding is suggestive of individual variability for response to estrogen supplementation, with a possible association for onset age. Caution is advised where estrogen is used to treat schizophrenic patients taking atypical antipsychotics.

Amisulpride versus risperidone in the treatment of schizophrenic patients: a double-blind pilot study in Taiwan.

BACKGROUND AND PURPOSE: The atypical antipsychotics, amisulpride and risperidone, have different receptor affinity characteristics. Although the relative efficacy of both drugs compared to conventional antipsychotics is well established, it remains unclear how the efficacy of amisulpride compares with risperidone. There have been no controlled studies comparing amisulpride to risperidone in Asian patients. The purpose of this study was to compare the efficacy and safety of amisulpride with that of risperidone in Taiwanese schizophrenic patients. METHODS: Patients with productive positive symptoms (n = 48) were enrolled into this double-blind, randomized pilot study for 6 weeks. Patients received either amisulpride (400-800 mg/day) or risperidone (4-8 mg/day). Positive and Negative Syndrome Scale (PANSS), Clinical Global Impression (CGI), Social and Occupational Functioning Assessment Scale (SOFAS), and patients' subjective responses to treatment were assessed during the trial period. Adverse events were recorded at each follow-up visit. RESULTS: At the end of the trial, the mean dosage was 630 +/- 134 mg/day and 6.88 +/- 1.54 mg/day for amisulpride and risperidone, respectively. There was no significant difference in the reduction of the PANSS total score (amisulpride -24.1 versus risperidone -28.4, p = 0.999), the PANSS positive subscale score (amisulpride -6.8 versus risperidone -8.3, p = 0.467), the PANSS negative subscale score (amisulpride -5.6 versus risperidone -6.4, p = 0.999), or the CGI score between the two groups. The extrapyramidal symptom ratings, the improvement in the SOFAS (amisulpride 11.1 versus risperidone 10.0) and the subjective response (amisulpride 82% versus risperidone 83%) were comparable. No serious adverse events were recorded in either treatment group. There was a statistically significant body weight gain in the risperidone group. In contrast, there was a statistically, though not clinically, significant reduction of blood pressure and heart rate in the amisulpride group. CONCLUSIONS: This study suggests that amisulpride is as effective as risperidone in the treatment of patients with schizophrenia. Both drugs were well tolerated, but had different side effect profiles.

Prevalence and associated factors of comorbid skin diseases in patients with schizophrenia: a clinical survey and national health database study.

OBJECTIVES: To examine the epidemiology of and possible risk factors for skin diseases in patients with schizophrenia. METHODS: All of 337 patients with schizophrenia were recruited from the therapeutic community of a psychiatric hospital and underwent a detailed skin examination. The National Health Insurance Research Database (NHIRD) was used to compare the prevalence of skin diseases between patients with schizophrenia and those without. RESULTS: In the clinical survey, fungal infection (61.4%) and dermatitis (46.9%) were the most common skin diseases. Clozapine users had a lower risk of fungal infection than those on typical antipsychotics [odds ratio (OR)=0.49, 95% confidence interval (CI)=0.30-0.81]. Obese patients were more likely to have fungal infections than those without (OR=1.93, 95% CI=1.20-3.09), and those with diabetes had an increased risk of bacterial infection than those without (OR=2.0, 95% CI=1.06-3.75). NHIRD revealed that the overall prevalence of skin diseases, including infections, dermatitis, hyperkeratosis, pilosebaceous disease, androgenic alopecia, xerosis and stasis, were higher in patients with schizophrenia than in those without (75.1% vs. 72.6%, P=.01). CONCLUSIONS: The prevalence of skin diseases is high in patients with schizophrenia, for whom proper skin care is necessary to improve their life quality.

Rapid development of fatal bowel infarction within 1 week after clozapine treatment: a case report.

Although there have been reported fatalities associated with clozapine-induced bowel infarction, in all of these cases, the patients had taken clozapine for months to years. We present here the case of a 47-year-old single man who died suddenly due to bowel infarction and sepsis 1 week after taking clozapine.

Validation of Chinese version of the MacArthur Competence Assessment Tool for Clinical Research (MacCAT-CR) in patients with schizophrenia spectrum disorders.

There is a lack of validated instruments assessing the decision-making capacity to consent to clinical research of patients with schizophrenia spectrum disorders who speak Chinese. This study aimed to determine the validity and reliability of the Chinese version of MacArthur Competence Assessment Tool for Clinical Research (MacCAT-CR). The MacCAT-CR using a hypothetical study, the Positive and Negative Syndrome Scale (PANSS), the Mini-Mental State Examination (MMSE) assessed 139 patients with schizophrenia or schizoaffective disorder. The Cronbach's alpha coefficient was 0.74. The intra-class coefficients for understanding, appreciation, and reasoning scores ranged from 0.53 to 0.81. Regarding validity, the understanding, appreciation and reasoning scores were negatively correlated with the PANSS (r ranged from -0.27 to -0.33), and the negative subscale score (r ranged from -0.31 to -0.37) as well as positively correlated with the MMSE (r ranged from 0.26 to 0.43). All pvalues were less than 0.01. The factor analysis explained 57.6 % of the total variance; specifically, Components 1 and 2 contributed 44.5% and 13.1 % of the variance respectively. These findings indicate that the Chinese version of the MacCAT-CR is a reliable and valid instrument to assess the decision-making capacity to consent to clinical research of patients with schizophrenia spectrum disorders.

Validation of the Taiwanese Mandarin version of the Personal and Social Performance scale in a sample of 655 stable schizophrenic patients.

OBJECTIVES: The aim of this study was to determine the validity and reliability of the Taiwanese Mandarin version of the Personal and Social Performance scale (TMV-PSP) using a structured interview and a computerized scoring calculator. METHODS: In total, 655 patients with schizophrenia or schizoaffective disorder were assessed with the TMV-PSP, the Positive and Negative Syndrome Scale (PANSS), the Global Assessment of Functioning-Severity (CGI-S), the Mini-Mental State Examination (MMSE), activities of daily living (ADL) and instrumental activities of daily living (IADL). Construct validity was assessed by factorial analysis. The internal consistency and temporal stability of the PSP were obtained by calculating intra-class correlation coefficients. RESULTS: The Cronbach's alpha coefficients of the TMV-PSP were 0.73. The patients' PSP showed a negative correlation with the PANSS (r = -0.65) and its subscales, including positive (r = -0.35), negative (r = -0.67), general factors (r = -0.62) and the CGI-S scores (r = -0.47). The PSP showed a positive correlation with MMSE scores (r = 0.59), ADL (r = 0.45) and IADL scores (r = 0.6). All p-values for the correlation coefficients were less than 0.001. Good test-retest reliability was obtained (intraclass coefficient = 0.91, 95 CI: 0.82-0.96, p = 0.0001). Factor analysis explained a total of 83.6% of the variance, with Component 1 contributing 58.4% and Component 2 contributing 24.8%. CONCLUSIONS: These findings indicate that the TMV-PSP using a structured interview and a computerized scoring calculator is a reliable and valid instrument for the assessment of social functioning in patients with schizophrenia.

Effects of video game playing on cerebral blood flow in young adults: a SPECT study.

To study the impact of video game playing on the human brain, the effects of two video games playing on cerebral blood flow (CBF) in young adults were determined. Thirty healthy subjects comprising 18 males and 12 females who were familiar with video game playing were recruited. Each subject underwent three sessions of single photon emission computed tomography (SPECT) with a bolus injection of 20 mCi (99m)Tc ECD IV to measure their CBF. The first measurement was performed as baseline, the second and third measurements were performed after playing two different video games for 30 min, respectively. Statistic parametric mapping (SPM2) with Matlab 6.5 implemented on a personal computer was used for image analysis. CBF was significantly decreased in the prefrontal cortex and significantly increased in the temporal and occipital cortices after both video games playing. Furthermore, decreased CBF in the anterior cingulate cortex (ACC) which was significantly correlated with the number of killed characters was found after the violent game playing. The major finding of hypo-perfusion in prefrontal regions after video game playing is consistent with a previous study showing reduced or abnormal prefrontal cortex functions after video game playing. The second finding of decreased CBF in the ACC after playing the violent video game provides support for a previous hypothesis that the ACC might play a role in regulating violent behavior.

Pharmacoeconomic evaluation of schizophrenia in Taiwan: model comparison of long-acting risperidone versus olanzapine versus depot haloperidol based on estimated costs.

Antipsychotics are the keystone in schizophrenia treatment. Although the benefits of the new generation of antipsychotics has been demonstrated over the last decade, the issues of patient compliance and higher purchasing price of atypical antipsychotics remain unresolved. Risperidone is the only atypical antipsychotic agent with long-acting formulation. Long-acting risperidone is a water-based injection and it has been associated with a low level of pain. The aim of the present study was to test whether an improvement in compliance with the use of a long-acting risperidone, compared with olanzapine and depot haloperidol, can increase the effectiveness and the cost-effectiveness indexes. An economic comparison model with decision tree, rather than a prospective design with real clinical drug trial, was applied. The unit cost for each medical procedure was obtained from the claimed-database of the Bureau of National Health Insurance in Taiwan. An executive committee simulated the incidence of extrapyramidal side-effects and proposed a therapeutic model for each strategy based on a literature review. The probabilities of treatment response of different agents and those of different mental health states were estimated by the executive committee and 10 senior psychiatrists who were randomly selected. Sensitivity analysis was performed for drug cost-effectiveness and compliance improvement for using long-acting risperidone. The results showed that long-acting risperidone is more cost-effective than either olanzapine or depot haloperidol for treating schizophrenia patients whose conditions are stable and whose illness duration ranges from 1 to 5 years. The comparison model with the Kaplan-Meier decision tree may serve as an alternative to prospectively designed studies for cost-effectiveness of atypical antipsychotics.

Smoking in chronic schizophrenic inpatients in taiwan.

OBJECTIVE: This study investigated the prevalence of smoking and its association with the clinical characteristics of Chinese inpatients with chronic schizophrenia. METHOD: Schizophrenic patients hospitalized in chronic wards were assessed using Brief Psychiatric Rating Scale (BPRS), Abnormal Involuntary Movements Scale (AIMS) and Folstein Mini-Mental Status Examination (MMSE) testing. RESULTS: Of 257 patients, 105 smoked and 4 had ceased. Males exhibited a higher prevalence of smoking than females (p < 0.001). Smoking was not significantly associated with age at onset (AAO), chlorpromazine equivalents, MMSE, AIMS, BPRS positive symptom subscale, BPRS negative symptom subscale or total BPRS scores. Smokers had higher BPRS general subscales. CONCLUSION: Compared to the general population, smoking prevalence was slightly higher in schizophrenic males, double in schizophrenic females, but no difference in refractory schizophrenic clozapine users. Smoking did not affect patient AAO or daily antipsychotic dose. Patients with a higher BPRS general subscale may smoke to relieve affective symptoms.

Association of muscarinic m1 receptor genetic polymorphisms with psychiatric symptoms and cognitive function in schizophrenic patients.

OBJECTIVE: The cholinergic system is important in the search for the pathophysiology of schizophrenia due to its role in cognitive function, interaction with the dopamine system in brain regions relevant to schizophrenia, side effects of antipsychotic medication and potential antipsychotic effect of muscarinic receptor antagonists. This study investigated the association of type I muscarinic receptor (CHRM1) genetic polymorphisms with the clinical characteristics of chronic schizophrenic inpatients. METHODS: We determined the genotype of CHRM1 genetic polymorphisms in 243 schizophrenic patients hospitalized in chronic care wards. Psychotic symptoms were assessed using the Brief Psychiatric Rating Scale (BPRS), and cognitive function was assessed using the Folstein Mini-Mental Status Examination (MMSE) test. Sixty of the 243 subjects also completed the Wisconsin Card Sorting Test (WCST). RESULTS: There was a significant difference in the number of correct responses and the percentage of perseverative errors in the WCST in the CHRM1 C267A genotype group of schizophrenia patients. There was no significant association between age at onset, chlorpromazine equivalents, BPRS scores, MMSE or schizophrenia per se in patients with the CHRM1 C267A genotype. The full exon of the CHRM1 gene was screened out with single-strand conformation polymorphism, and 2 single nucleotide polymorphisms (C267A and C1353T) were identified in our patients and control subjects. These 2 single nucleotide polymorphisms were linked together without exception. CONCLUSION: This study demonstrated that in schizophrenic patients, the heterozygote group of CHRM1 C267A polymorphism (267C/A) had more correct responses and less perseverative errors on the WCST performance than the 267C/C homozygote group, implicating that this polymorphism may be related to prefrontal cortical function. Our results also suggested that the C267A polymorphism plays no major role in the susceptibility to and clinical manifestations of schizophrenia.