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Biomedical subjects

William T Carpenter

Publications and source records attributed to William T Carpenter.

At least 19 recordsLinked to original sources
PubMed2006

Lack of association between COMT gene and deficit/nondeficit schizophrenia.

BACKGROUND: The dopamine dysregulation hypothesis of schizophrenia posits that positive, negative and cognitive symptoms correlate with cortical/subcortical imbalances in dopaminergic transmission. A functional polymorphism (Val158Met) in the catechol-O-methyltransferase (COMT) gene is implicated in the pathophysiology of schizophrenia by its effect on prefrontal dopamine transmission, and its unique impact on prefrontal cognitive and behavioral phenotypes. Cognitive impairments and negative symptoms in schizophrenia have been hypothesized to be associated with hypodopaminergic states. Schizophrenia patients with the deficit syndrome are characterized by primary enduring negative symptoms, impairment on neurocognitive tasks sensitive to frontal and parietal cortical functioning, and poorer functional outcome compared to non-deficit patients. METHODS: Eighty-six schizophrenia cases that met DSM-IV criteria for schizophrenia were recruited. Additional categorization into deficit and nondeficit syndrome was performed using the Schedule for the Deficit Syndrome (SDS). A healthy comparison group (n = 50) matched to cases on age and ethnicity was recruited. Allele and genotype frequencies of the Val158Met polymorphism were compared among healthy controls, and schizophrenia cases with the deficit (n = 21), and nondeficit syndrome (n = 65). RESULTS: There was a significant difference in Val/Val genotype frequencies between schizophrenia cases (combined deficit/nondeficit) and healthy controls (p = 0.004). No significant differences in allele or genotype frequencies were observed between deficit and nondeficit cases. CONCLUSION: Results from this preliminary analysis failed to show an effect of COMT gene on deficit schizophrenia.

Journal Article↗
PubMed2006

Neuropsychology of the deficit syndrome: new data and meta-analysis of findings to date.

The deficit syndrome is thought to characterize a pathophysiologically distinct subgroup of patients with schizophrenia. Supporting this notion, prior research examining the neuropsychological correlates of the deficit syndrome has suggested the presence of a differential impairment in frontal and parietal functions. This article reports findings from 2 studies attempting to replicate and extend previous reports of a differential neuropsychological impairment in deficit schizophrenia. In the first study, we administered a comprehensive neuropsychological battery to 20 deficit and 25 nondeficit patients with schizophrenia and 25 normal healthy controls. In the second study, a meta-analysis was conducted of 13 separate studies examining the neuropsychology of the deficit syndrome. There was little evidence from either of the present studies that the deficit syndrome is associated with a selective impairment in frontal and parietal lobe functions. The first study failed to find significant differences in frontal or parietal abilities for deficit vs nondeficit patients. The meta-analytic findings revealed that deficit patients were globally more neuropsychologically impaired than nondeficit patients (effect size [ES] = 0.41). Relative to nondeficit patients, deficit patients performed poorest on tests of olfaction (ES = 1.11), social cognition (ES = 0.56), global cognition (ES = 0.52), and language (ES = 0.51). The neuropsychological impairments associated with the deficit form of schizophrenia do not follow an obvious anatomically defined pattern of impairment. The question of whether deficit patients exhibit a unique cognitive impairment profile will require a more sophisticated and rigorous examination of the neuropsychology of the deficit syndrome.

Adult↗
PubMed2006

Treatment of schizophrenia negative symptoms: future prospects.

New findings from neuroscience, genetics, and experimental psychology have emerged that provide alternative explanations of many negative symptoms. We review the continuing limitations in treatment and discuss possible sources of heterogeneity among negative symptoms. We also anticipate conceptual uncertainties that may arise with forthcoming treatment developments.

Antipsychotic Agents↗
PubMed2006

Correlations between rCBF and symptoms in two independent cohorts of drug-free patients with schizophrenia.

We report on the correlations between whole brain rCBF and the positive and negative symptoms of schizophrenia in two cohorts of patients who were scanned while free of antipsychotic medication. We hypothesized that positive symptoms would correlate with rCBF in limbic and paralimbic regions, and that negative symptoms would correlate with rCBF in frontal and parietal regions. Both cohorts of patients with schizophrenia (Cohort 1: n=32; Cohort 2: n=23) were scanned using PET with H(2)(15)O while free of antipsychotic medication for an average of 21 and 15 days, respectively. Both groups were scanned during a resting state. Using SPM99, we conducted pixel by pixel linear regression analyses between BPRS scores and whole brain rCBF. As hypothesized, positive symptoms correlated with rCBF in the anterior cingulate cortex (ACC) in a positive direction and with the hippocampus/parahippocampus in a negative direction in both patient groups. When the positive symptoms were further divided into disorganization and hallucination/delusion scores, similar positive correlations with ACC and negative correlations with hippocampus rCBF were found. In both cohorts, the disorganization scores correlated positively with rCBF in Broca's area. As expected, negative symptoms correlated inversely with rCBF in frontal and parietal regions. This study provides evidence that limbic dysfunction may underlie the production of positive symptoms. It suggests that abnormal function of Broca's area may add a specific language-related dimension to positive symptoms. This study also provides further support for an independent neurobiological substrate of negative symptoms distinct from positive symptoms. The involvement of both frontal and parietal regions is implicated in the pathophysiology of negative symptoms.

Adolescent↗
PubMed2005

Dihydropyrimidinase-related protein 2 (DRP-2) gene and association to deficit and nondeficit schizophrenia.

A previous study has shown an association between the *2236T > C allele polymorphism of the dihydropyrimidinase-related protein 2 (DRP-2) gene and schizophrenia in a Japanese sample [Nakata et al. (2003); Biological Psychiatry 53:571-576]. DRP-2 is an important molecule in guiding neuronal development and its gene is located in 8p21, a chromosomal region that was previously shown to have significant linkage to schizophrenia and to several deficit symptoms of schizophrenia. We compared the frequency of the DRP-2 *2236T > C polymorphism between subjects with (n = 117) and without (n = 72) schizophrenia, and then further evaluated whether the association was specific for the deficit (n = 24) and nondeficit (n = 93) forms of schizophrenia. In both Caucasians and African-Americans, the C allele occurred more frequently in schizophrenia cases than controls, with this difference achieving statistical significance in Caucasians (C allele frequency: 42.0% in cases vs. 25.0% in controls, P = 0.014) but not African Americans (52.6% in cases vs. 50.0% in controls, P = 0.93). In Caucasians, the frequency of the C allele was significantly higher in both the deficit (allele frequency 53.3%, P = 0.009) and nondeficit (39.2%, P =0.050) forms of schizophrenia compared to controls (allele frequency 25.0%). We conclude that the DRP-2 *2236 C allele may mark another polymorphism in DRP-2, or in a nearby gene, that may influence susceptibility to schizophrenia.

Adult↗
PubMed2005

Olanzapine treatment of residual positive and negative symptoms.

OBJECTIVE: Olanzapine has been hypothesized to have superior efficacy in patients with treatment-resistant schizophrenia. The authors examined the comparative efficacy and safety of olanzapine and haloperidol in outpatients with partially responsive schizophrenia. METHOD: Sixty-three outpatients with schizophrenia who met retrospective and prospective criteria for either residual positive or residual negative symptoms entered a 16-week double-blind, parallel-groups comparison of olanzapine and haloperidol. RESULTS: There were no significant differences between the two drugs in their effect on positive or negative symptoms. There were no significant differences between the two treatment groups on measures of social and functional outcome. Olanzapine-treated patients had a significant reduction in extrapyramidal symptoms and subjective measures of stiffness and dry mouth, but the increases in systolic blood pressure and weight in olanzapine-treated patients were significantly greater than they were in haloperidol-treated patients. CONCLUSIONS: Olanzapine has limited differential benefit for either positive or negative symptoms in patients with treatment-resistant schizophrenia. Although olanzapine is associated with fewer extrapyramidal symptoms, other side effects may offset this benefit.

Adult↗
PubMed2005

Remission in schizophrenia: proposed criteria and rationale for consensus.

New advances in the understanding of schizophrenia etiology, course, and treatment have increased interest on the part of patients, families, advocates, and professionals in the development of consensus-defined standards for clinical status and improvement, including illness remission and recovery. As demonstrated in the area of mood disorders, such standards provide greater clarity around treatment goals, as well as an improved framework for the design and comparison of investigational trials and the subsequent evaluation of the effectiveness of interventions. Unlike the approach to mood disorders, however, the novel application of the concept of standard outcome criteria to schizophrenia must reflect the wide heterogeneity of its long-term course and outcome, as well as the variable effects of different treatments on schizophrenia symptoms. As an initial step in developing operational criteria, an expert working group reviewed available definitions and assessment instruments to provide a conceptual framework for symptomatic, functional, and cognitive domains in schizophrenia as they relate to remission of illness. The first consensus-based operational criteria for symptomatic remission in schizophrenia are based on distinct thresholds for reaching and maintaining improvement, as opposed to change criteria, allowing for alignment with traditional concepts of remission in both psychiatric and nonpsychiatric illness. This innovative approach for standardizing the definition for outcome in schizophrenia will require further examination of its validity and utility, as well as future refinement, particularly in relation to psychosocial and cognitive function and dysfunction. These criteria should facilitate research and support a positive, longer-term approach to studying outcome in patients with schizophrenia.

Brief Psychiatric Rating Scale↗
PubMed2005

Optimistic bias in the perception of personal risk: patterns in schizophrenia.

OBJECTIVE: Biases in the perception of personal vulnerability to risk could influence how individuals make decisions in many contexts. Schizophrenia patients, because of neurocognitive deficits and psychiatric symptoms, are often seen as compromised in their ability to appreciate risk information and in their decision-making capacity. The authors investigated whether schizophrenia patients share the same optimistic biases frequently demonstrated by non-ill adults in their perceptions of personal risk. METHOD: Twenty-five schizophrenic outpatients and 23 healthy comparison subjects completed a risk perception questionnaire on which they compared their own likelihood of experiencing adverse events to that of other adults. Questionnaire items were adverse events of three types: controllable, uncontrollable, and neutral. The degree to which subjects rated their own likelihood of experiencing adverse events as lower than others' was an index of optimistic bias. RESULTS: Although both groups showed an optimistic bias in general, healthy comparison subjects demonstrated a greater level of optimism than did schizophrenia patients, especially for events typically perceived as controllable. Psychiatric symptoms rated with the Brief Psychiatric Rating Scale and the Scale for the Assessment of Negative Symptoms bore little relationship to patients' ratings on the risk questionnaire. CONCLUSIONS: Results showed that an unrealistically optimistic bias in the perception of personal risk was at least as evident in a healthy comparison group as in a schizophrenia group. Such a bias could influence decision making. By identifying and responding to such biases, clinicians and researchers can promote more fully informed and rational decisions in patients and healthy adults.

Adult↗
PubMed2005

First-episode schizophrenia: a focus on pharmacological treatment and safety considerations.

Schizophrenia is a debilitating disorder, which is usually chronic, and is one of the most devastating medical illnesses. Early and appropriate treatment with antipsychotics is an important strategy for patients with first-episode schizophrenia. However, there are many possible safety issues for patients with schizophrenia that should be considered and properly addressed. Depressive symptoms and suicidal behaviour commonly occur in first-episode schizophrenic patients, and every effort should be made to treat and minimise these symptoms. There are also important issues and considerations in young and first-episode patients that should also be considered in the emergency treatment setting and for minimising medication nonadherence in this population. Most importantly, adverse effects should be considered, minimised and addressed. While first- and second-generation antipsychotics (SGAs) both appear to offer similar efficacy for amelioration of positive symptoms in first-episode patients, SGAs may offer better tolerability, specifically regarding extrapyramidal symptoms (EPS) and tardive dyskinesia risk, and some prolactin-sparing benefits. However, these medications do cause a host of adverse effects, including weight gain, metabolic disturbances, corrected QT interval prolongation and prolactin-related adverse effects, which are important considerations relating to both the short- and long-term safety of patients with schizophrenia being treated with SGAs. Clozapine and olanzapine are most likely to cause weight gain and metabolic effects, while risperidone is more likely to cause EPS and prolactin elevations. Most antipsychotics should be used in low doses to minimise adverse effects and each medication should be optimised in a highly individualised way to maximise adherence and treatment outcomes and minimise tolerability and safety concerns. At some point in their lives, these patients will most probably experience periods of depression, suicidal behaviours, adverse effects and nonadherence, and every effort should be made to minimise or prevent these from occurring. Thus, safety concerns in this group of young patients, in the beginning of their first psychotic episode, are a major issue as they are starting a journey of antipsychotic treatment that is likely to last for the remainder of their lives.

Age of Onset↗
PubMed2004

Clinical constructs and therapeutic discovery.

Schizophrenia, as a single disease entity, has been the major paradigm during the past 100 years. Classification has increasingly emphasized diagnostically discriminating psychotic symptoms. This has made reality distortion and thought disorder the defining qualities of the disorder. One result is 50 years of developing dopamine antagonist antipsychotic drugs while neglecting novel therapeutic pathways related to nonpsychotic pathology. The domains of psychopathology provides an alternative paradigm. In this paradigm, the relative independence of reality distortion, disorganization, negative pathology, and impairments in cognition is stressed. Application of this paradigm has revealed that impaired cognition and negative symptoms are robustly associated with poor functional outcomes. Antipsychotic drugs fail to address these pathologies. These unmet treatment needs are clinical targets for drug discovery involving novel therapeutic pathways.

Antipsychotic Agents↗
PubMed2004

Neuroplasticity and schizophrenia.

This article's title is also the name of a workshop sponsored by the International Congress on Schizophrenia Research that was focused on an appraisal of the potential role of neuroplastic processes in the etiology or course of schizophrenia. The workshop brought together clinical investigators of schizophrenia and basic scientists who study various aspects of neuroplasticity, including central nervous system (CNS) development, learning and memory, and drug action. The goal was to identify special opportunities to advance knowledge and understanding of schizophrenia pathology, treatment, or prevention by applying neuroplasticity concepts as a framework to theories of the illness. Although the focus of this workshop was schizophrenia, the phenomena considered are pertinent to other disorders, such as depression and drug abuse.

Animals↗