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Biomedical subjects

S A Chong

Publications and source records attributed to S A Chong.

At least 19 recordsLinked to original sources
PubMed2003

Clinical characteristics and associated factors in antipsychotic-induced akathisia of Asian patients with schizophrenia.

OBJECTIVE: We studied the prevalence of akathisia and its relationship to a number of sociodemographic and clinical factors in a population of Chinese inpatients with Schizophrenia. METHOD: Six-hundred and forty-five patients were recruited for the study. Akathisia was assessed using the Barnes Akathisia Rating Scale (BARS), dyskinesia by the Abnormal Involuntary Movement Scale (AIMS) and extrapyramidal side effects (EPSE) were assessed by the Simpson-Angus Rating Scale (SARS). RESULTS: Only 35 (5%) patients were assessed to have akathisia. There was no gender or ethnic difference in the rates of akathisia. However, the majority of the patients (65%) were receiving an anticholinergic agent at the time of the study. CONCLUSION: Our findings of an overlap between TD and EPSE support the suggestion that there may be a common vulnerability for these movement disorders. The finding of a low rate of akathisia among our Asian patients suggests an inter-ethnic difference in the vulnerability for the development of akathisia. However, comparing our results with the rates reported from other countries may be hampered by the diagnostic and methodological differences across studies.

Akathisia, Drug-Induced↗
PubMed2002

Thyroid dysfunction in chronic schizophrenia within a state psychiatric hospital.

OBJECTIVES: This study seeks to determine the prevalence and pattern of thyroid dysfunction in a group of adult psychiatric inpatients with chronic schizophrenia. We also hypothesize that raised thyroid hormones are associated with more severe psychopathology. METHODS: Thyroid function tests were performed on 189 patients and the Brief Psychiatric Rating Scale (BPRS) was administered by a single rater on all patients. RESULTS: There was a high prevalence of (36.4%) thyroid function test abnormalities but all patients except 1 were assessed to be clinically euthyroid. Free thyroxine (fT4) and triiodothyronine (fT3) were significantly higher in patients with mild (BPRS score, 10-20) and major syndrome (BPRS score, equal or above 21) compared to no syndrome (BPRS score, 0-9). No correlation was found between thyroid hormones and neuroleptic use. CONCLUSION: Although thyroid function test abnormalities are common in patients with chronic schizophrenia, clinical thyroid illness was absent. This calls for caution in the use and interpretation of thyroid function tests in patients with chronic schizophrenia.

Adult↗
PubMed2001

Susceptibility to neuroleptic-induced tardive dyskinesia and the T102C polymorphism in the serotonin type 2A receptor.

BACKGROUND: Genetic factors have been implicated in the pathophysiology of the movement disorder tardive dyskinesia, which may involve dopamine-serotonin interaction. Case-control association studies have identified the T102C polymorphism of the 5-HT2A receptor gene as being associated with schizophrenia and responsiveness to clozapine. In this study, we examine the association of this polymorphism in the 5-HT2A receptor gene as a risk factor for developing schizophrenia and tardive dyskinesia from prolonged treatment with neuroleptics. METHODS: Ninety-seven healthy control subjects with no history of mental illness and 221 schizophrenic patients (87 with tardive dyskinesia, 134 without) were genotyped by PCR-RFLP. RESULTS: Comparison between cases and control subjects revealed no significant association between the C allele and schizophrenia. There was significant difference in allele frequency (p = .044, OR = 1.54 95% CI = 1.02-2.33) between patients who developed tardive dyskinesia and those who did not. Significant difference remains even after adjusting for age and neuroleptic dosage (p = .041) with the odds ratio at 1.64 (95% CI = 1.02-2.62). CONCLUSIONS: A genetic variant of the 5-HT2A receptor may be associated with neuroleptic-induced tardive dyskinesia in schizophrenia. Further studies are needed to replicate the finding. The role of 5-HT2A receptor in the etiology of tardive dyskinesia or treatment-resistant schizophrenia should be further investigated.

Antipsychotic Agents↗
PubMed2001

Zn2+-induced ERK activation mediated by reactive oxygen species causes cell death in differentiated PC12 cells.

Recent studies have provided evidence that Zn2+ plays a crucial role in ischemia- and seizure-induced neuronal death. However, the intracellular signaling pathways involved in Zn2+-induced cell death are largely unknown. In the present study, we investigated the roles of mitogen-activated protein kinases (MAPKs), such as c-Jun N-terminal kinase (JNK), p38 MAPK and extracellular signal-regulated kinase (ERK), and of reactive oxygen species (ROS) in Zn2+-induced cell death using differentiated PC12 cells. Intracellular accumulation of Zn2+ induced by the combined application of pyrithione (5 microM), a Zn2+ ionophore, and Zn2+ (10 microM) caused cell death and activated JNK and ERK, but not p38 MAPK. Preventing JNK activation by the expression of dominant negative SEK1 (SEKAL) did not attenuate Zn2+-induced cell death, whereas the inhibition of ERK with PD98059 and the expression of dominant negative Ras mutant (RasN17) significantly prevented cell death. Inhibition of protein kinase C (PKC) and phosphatidylinositol-3 kinase had little effect on Zn2+-induced ERK activation. Intracellular Zn2+ accumulation resulted in the generation of ROS, and antioxidants prevented both the ERK activation and the cell death induced by Zn2+. Therefore, we conclude that although Zn2+ activates JNK and ERK, only ERK contributes to Zn2+-induced cell death, and that ERK activation is mediated by ROS via the Ras/Raf/MEK/ERK signaling pathway.

Animals↗
PubMed2001

Awareness of tardive dyskinesia in Asian patients with schizophrenia.

While ethnocultural differences in risk of tardive dyskinesia (TD) have been suggested, no previous studies have examined whether this factor also plays a role in lack of awareness of TD. This study examined this question in an Asian population with schizophrenia. Six hundred seven patients in a state mental hospital in Singapore were assessed using the Abnormal Involuntary Movement Scale (AIMS) and the Simpson-Angus Rating Scale. Of the 607 patients, 242 (39.9%) met criteria for TD, and 163 (67.4%) patients were not aware of the presence of TD. No significant differences in terms of age, gender, and duration of illness were found between those aware of their TD and those not aware. Daily neuroleptic doses and scores for the AIMS and Simpson-Angus Rating Scale were significantly different, although after logistic regression, only the Simpson-Angus Rating Scale scores remained significant. The finding that a large proportion of our patients lacked awareness of their TD is consistent with other reports in the West and provides evidence that this feature is characteristic of the illness rather than of a specific ethnocultural group. We found an association between lack of awareness and greater severity of extrapyramidal symptoms (EPS), suggesting that there may be a subtype of TD in which lack of awareness and greater vulnerability of developing EPS are features.

Adult↗
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↗