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Biomedical subjects

S A Chong

Publications and source records attributed to S A Chong.

At least 37 records · Page 2Linked to original sources
PubMed2001

The effect of risperidone on cognitive functioning in a sample of Asian patients with schizophrenia in Singapore.

OBJECTIVE: To evaluate the effect of risperidone treatment on the cognitive functioning in a group of Asian patients with schizophrenia METHOD: Patients with DSM-IIIR schizophrenia were recruited from Woodbridge Hospital. Several domains of cognitive functions were assessed at baseline before washout, at 8 weeks and 6 months after initiation of treatment on risperidone. Clinical outcome was assessed on the Positive and Negative Syndrome Scale (PANSS). RESULTS: Significant improvements were found in verbal fluency and certain aspects of memory 8 weeks after risperidone treatment. There were significant improvements in executive and memory functioning after 6 months. Improvements were also noted in attention and perceptual/motor processes although these did not reach significant levels. Treatment on risperidone also resulted in significant reduction in the PANSS score. CONCLUSION: Our results are consistent with those found in other studies in which risperidone was shown to be effective in improving several aspects of cognitive functioning. There were corresponding effectiveness in treating positive and negative symptoms of schizophrenia. Such improvements can have positive implications on vocational and social functioning.

Adult↗
PubMed2001

Cardiac effects of psychotropic drugs.

INTRODUCTION: The incidence of mortality is higher among psychiatric patients than among the general population and the cause of which may be the psychiatric disorder itself or other related factors like life-style and medications. Sudden death has been associated with certain psychotropic drugs and the underlying cause(s) have been suggested to be some adverse cardiac complications. We reviewed the literature for the cardiac effects attributed to psychotropic drugs. METHODS: A Medline and manual search of the literature on the cardiac effects attributed to the psychotropic drugs was performed. We limited ourselves to the main psychotropic drugs (antipsychotics, antidepressants, mood stabilizers, and benzodiazepines) that are available in Singapore. RESULTS: The search showed that certain drugs carry a greater potential for adverse cardiac complications. Among the antipsychotics, thioridazine has a greater risk for cardiac events. The tricyclic antidepressants also have significant effect on the heart rate, blood pressure as well as having the propensity to cause prolonged QTc, whereas the selective serotonin reuptake inhibitors (SSRIs) are generally safe. Among the mood stabilizers, lithium and carbamazepine have been associated with sinus node arrhythmias while sodium valproate is relatively free of any untoward cardiac effect. The benzodiazepines are in general safe even in patients with myocardial infarction and coronary bypass. CONCLUSIONS: In patients with higher risk of cardiac complications (elderly, pre-existing cardiac disorders, concurrent medications with potential cardiac effects and poor metabolizers), the choice of psychotropic drugs where indicated has to be considered with these factors in mind as well as the inherent risk of these psychotropic drugs. Monitoring of the blood pressure, heart rate and ECG should be done regularly.

Arrhythmias, Cardiac↗
PubMed2000

Attempted suicide and polymorphism of the serotonin transporter gene in Chinese patients with schizophrenia.

Abnormalities of serotonin synthesis and metabolism may be associated with suicidality. The serotonin transporter gene (5-HTT) is one of the important genes involved in the regulation of serotonin neurotransmission. We examined the association of suicidal behavior in Chinese schizophrenic patients with a functional polymorphism of the promoter region of the 5-HTT gene (5-HTTLPR). The 5-HTTLPR genotype was determined by polymerase chain reaction for 76 suicidal and 262 non-suicidal patients with a diagnosis of schizophrenia (DSM-IV criteria). All subjects were unrelated to each other, and all were Chinese. There was no significant genotypic or allelic association of the 5-HTTLPR polymorphism with history of attempted suicide. From our results, this 5-HTTLPR polymorphism is unlikely to have a major effect on suicidal behavior in Chinese patients with schizophrenia.

Adult↗
PubMed2000

Tardive dyskinesia is not associated with the serotonin gene polymorphism (5-HTTLPR) in Chinese.

Neuroleptics are the mainstay of treatment for schizophrenia, but one of the complications is the development of tardive dyskinesia (TD). The pathophysiology of TD may involve dopamine-serotonin interaction. The serotonin transporter participates in the reuptake and termination of serotonin neurotransmission, and the gene that codes for this protein is thus a candidate gene for the development of TD. There is a functional polymorphism in the transcriptional control region of the serotonin transporter gene, and we investigated the association between this polymorphism and TD in Chinese schizophrenic patients. The patients who did not differ in age and sex distribution did not show variation on the rates of TD and Abnormal Involuntary Movements Scale (AIMS) scores with genotypes. Our findings suggest that 5-HTTLPR polymorphism is not a risk factor for TD in Chinese. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:712-715, 2000.

Adult↗
PubMed2000

Neuroleptic and anticholinergic drug use in Chinese patients with schizophrenia resident in a state psychiatric hospital in Singapore.

OBJECTIVE: The objective of this study was to survey the prescribing pattern in Chinese patients with chronic schizophrenia in a state mental hospital in Singapore, and to compare our findings with those of surveys of Chinese patients in other countries. METHOD: We surveyed the use of neuroleptic and anticholinergic agents among Chinese patients with chronic schizophrenia (n = 534) in a state mental hospital in Singapore. RESULTS: Fifty-nine per cent of the patients received two or more neuroleptics (median daily dose of 400 mg chlorpromazine equivalents, range 50-2875 mg). There were no differences in gender distribution between those prescribed multiple neuroleptics as against an older group of those receiving none or only one neuroleptic medication. Sixty-six per cent of the patients were receiving depot neuroleptics, with more than half of these subjects also receiving additional oral neuroleptics. Patients who were prescribed multiple neuroleptics received significantly higher total doses than those receiving just one neuroleptic. Only 1% of patients were prescribed an atypical neuroleptic. Sixty-five per cent of patients were prescribed an anticholinergic agent. Those prescribed anticholinergic agents were younger, in receipt of higher doses of neuroleptic medications and had lower Simpson-Angus scores for extrapyramidal side-effects. CONCLUSIONS: The pervasive use of multiple typical neuroleptics, marked underutilisation of atypical neuroleptics, and the lack of anticholinergic medication in patients who might benefit from such treatment are issues of substantial concern, warranting action in both psychiatry practice and mental health policy.

Adult↗
PubMed2000

Clozapine augmentation: safety and efficacy.

While clozapine has been demonstrated to be efficacious in refractory schizophrenia and possibly schizoaffective as well as bipolar disorders, a substantial number of patients still remain unresponsive. One strategy in treating these refractory patients is to augment clozapine with other somatic treatments. This article reviews the efficacy and safety of the combination of clozapine with other somatic treatments. A total of 70 articles were obtained from a manual, as well as computerized (Medline), search of the English language literature from 1978 to March 1998. Few controlled studies exist; most were case reports/series. From these data, the greatest risk of adverse effects seems to be associated with clozapine combined with benzodiazepines, valproate, or lithium, but no currently evaluated combination is absolutely unsafe. In terms of efficacy, the data suggest a number of potential augmentation strategies, although controlled data are few. Combination therapies with clozapine are common in clinical practice, despite a lack of empirical data, and the benefits and risks of these combinations need to be systematically reviewed.

Antipsychotic Agents↗
PubMed2000

Effect of clozapine on polypharmacy.

Prescribing patterns for a group of outpatients with schizophrenia were surveyed for changes after the initiation of clozapine. Data were drawn from computerized pharmacy records, direct case record reviews, and interviews with the attending psychiatrists. The number of patients with two or more psychotropic drugs decreased by 31 percent after the initiation of clozapine, and a trend toward the use of clozapine without additional neuroleptics was detected. Decreases occurred in the use of anticholinergic agents, carbamazepine, and benzodiazepines, but selective serotonin reuptake inhibitors and sodium valproate were more likely to be prescribed concomitantly with clozapine.

Adult↗
PubMed2000

Contrasting clozapine prescribing patterns in the east and west?

INTRODUCTION: Polypharmacy is common in the treatment of schizophrenia and it may be especially common in the East. In this survey, we compared the effect of clozapine, an atypical neuroleptic, on polypharmacy in two groups of patients with schizophrenia in two different settings. MATERIALS AND METHODS: The medical charts of patients on stable doses of clozapine from a Canadian psychiatric centre and that of a Southeast Asian centre were analysed to evaluate the daily dose requirement and the concomitant medications prescribed. The beliefs of the Asian psychiatrists on the concomitant use of another neuroleptic were also examined. RESULTS: The mean daily dose of clozapine was 408 mg/day for the Canadian subjects and 169 mg/day for the Asian sample. Of the Canadian sample, none were prescribed another neuroleptic, 45% were on a benzodiazepine, and 10% were receiving an anticholinergic agent. The Singapore sample indicated 28% of the subjects on another neuroleptic, with 36% taking an anticholinergic agent and 28% on a benzodiazepine. The Asian psychiatrists prescribed a second neuroleptic in the belief that it would reduce cost and enhance the antipsychotic effect. CONCLUSIONS: This study suggests that there are regional differences in the prescription patterns and daily dose requirements of clozapine.

Adult↗
PubMed2000

Identification of genes for schizophrenia susceptibility.

INTRODUCTION: Advances in genotyping, mapping and genome analysis methods over the last few years offer great promise towards the discovery of genes involved in the pathogenesis of schizophrenia, a mental disorder with a high degree of heritability. METHODS: This article draws on published reports in major international journals in the field of schizophrenia and human genetics. RESULTS: We summarise the major findings from family linkage studies, genome scan with microsatellite markers and association studies with polymorphisms in candidate genes. However, although recent developments in the technology for genotyping and gene identification have provided new leads to genetic abnormalities underlying schizophrenia, they have yet to result in the identification of any disease gene. There are both positive and negative data for reported linkages to specific chromosomal regions and candidate gene polymorphisms. CONCLUSIONS: Conflicting data and nonreplication of association and linkage studies are problems that need to be addressed. One solution might be clearer and narrower definition of subphenotypes and use of only a specific phenotypic marker in linkage and association studies. When successful, identification of susceptibility genes will lead to better understanding of cognitive functions and socio-emotional behaviour and also help in the formulation of preventive strategies for those found to be at high risk.

Chromosomes, Human↗
PubMed1999

Clinical evaluation of risperidone in Asian patients with schizophrenia in Singapore.

OBJECTIVE: To evaluate the short-term efficacy and safety of risperidone in a group of Asian patients with schizophrenia in an 8-week open-label, prospective study. METHODS: Patients with DSM-IV schizophrenia were recruited from Woodbridge Hospital. After a washout period, they were started on a 56-day trial of risperidone. Outcome was assessed with the positive and negative syndrome scale (PANSS), the clinical global impression scale (CGI) and the extrapyramidal symptom rating scale (ESRS). RESULTS: The mean daily risperidone dose at end point was 5.6 mg (range, 3 to 8 md/day). Mean PANSS scores were reduced significantly from 78 +/- 15.1 at baseline to 56.6 +/- 10.9 at end point. Seventeen patients (85%) who were treatment responders, showed at least a 20% reduction in total PANSS scores at end point while nine patients (45%) had a greater than 50% reduction in the total PANSS scores. According to the CGI scale, 85% improved at end point. The severity of extrapyramidal symptoms (mean ESRS scores) were significantly lower at end point than at baseline. CONCLUSIONS: Risperidone was effective in the treatment of positive and negative symptoms of schizophrenia.

Adult↗
PubMed1999

Conventional versus novel antipsychotics: changing concepts and clinical implications.

Novel antipsychotics represent a significant advance in the treatment of schizophrenia after many years of few developments. The conventional antipsychotics are potent D2 antagonists, but fail to achieve a response in about 30% of cases. They are also associated with a high rate of extrapyramidal side effects. The greater and broader spectrum of efficacy combined with the reduced short- and long-term side effects of the new drugs such as quetiapine, risperidone, olanzapine and ziprasidone, contribute to a fresh optimism for the pharmacotherapy of schizophrenia. These novel agents are now driving further advances in schizophrenia research through a growing understanding of their pharmacological and clinical profiles. Clozapine, the first novel antipsychotic, has relatively low activity at D2 receptors, a high affinity for D4 receptors and a greater 5-HT2 (serotonin) than D2 antagonism. Hence, clozapine and other novel antipsychotics can be classified as such by this latter characteristic. However, some of these drugs have D2 occupancy greater than 60% (the clinical response threshold), while others have a lower D2 occupancy. The novel antipsychotics according have also been classified according to their activity on different neurotransmitter systems. While more effective, novel antipsychotics are not a panacea; they have limitations and side effects. In clinical practice, the American Psychiatric Association recommends either a conventional or novel antipsychotic for initial treatment of schizophrenia, whereas Canadian guidelines recommend novel agents. These agents should also be considered for treatment of refractory schizophrenia. Patients whose schizophrenia does not respond to one of these agents may respond to another. Future research should involve longer clinical trials, given the long periods needed to establish efficacy, and should address many remaining questions about the novel agents.

Antipsychotic Agents↗