Papers by Takefumi Suzuki
Neuropsychopharmacology, Nov 26, 2019
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Japanese journal of psychopharmacology, Apr 1, 2014
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Schizophrenia Research, Mar 1, 2022
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The Journal of Clinical Psychiatry, Dec 28, 2016
Although hyperprolactinemia carries a long-term risk of morbidity, the threshold of dopamine D2/3... more Although hyperprolactinemia carries a long-term risk of morbidity, the threshold of dopamine D2/3 receptor (D2/3R) occupancy for hyperprolactinemia has not been investigated in older patients with schizophrenia. Data were taken from a positron emission tomography (PET) study conducted between August 2007 and August 2015. The present post hoc study included 42 clinically stable outpatients with schizophrenia (DSM-IV) (mean ± SD age = 60.2 ± 6.7 years) taking olanzapine or risperidone. Subjects underwent [¹¹C]-raclopride PET scans to measure D2/3R occupancy before and after reducing their dose of antipsychotic by up to 40%. Blood samples were collected before each PET scan to measure prolactin levels. The relationship between prolactin levels and D2/3R occupancy was examined using stepwise linear regression analyses. The D2/3R occupancy thresholds for hyperprolactinemia were explored using Fisher exact tests. Prolactin levels decreased following dose reduction (mean ± SD = 24.1 ± 30.2 ng/mL to 17.2 ± 15.1 ng/mL; P < .001). Prolactin levels were associated with female gender (β = .32, P = .006, vs male), antipsychotics (β = .23, P = .02, risperidone vs olanzapine), and D2/3R occupancy (β = .23, P = .04). Those with D2/3R occupancy of 66% or higher were more likely to have hyperprolactinemia than those with D2/3R occupancy lower than 66% (P = .03). Sensitivity, specificity, positive predictive value, and negative predictive value of this threshold were 0.44, 0.81, 0.78, and 0.48, respectively. We identified a D2/3R occupancy threshold for hyperprolactinemia of 66% in older patients with schizophrenia, which is lower than that reported in younger patients (73%) by other researchers. Our results suggest a higher sensitivity to antipsychotics in older patients. Prolactin levels could assist in the determination of appropriate antipsychotic dosing to minimize adverse effects. ClinicalTrials.gov identifier: NCT00716755.
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Schizophrenia Research, Feb 1, 2012
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Schizophrenia Research, Apr 1, 2010
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Schizophrenia Research, Mar 1, 2015
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British Journal of Clinical Pharmacology, 2022
AIM Develop a robust and user-friendly software tool for the prediction of dopamine D2 receptor o... more AIM Develop a robust and user-friendly software tool for the prediction of dopamine D2 receptor occupancy (RO) in patients with schizophrenia treated with either olanzapine or risperidone, in order to facilitate clinician exploration of the impact of treatment strategies on RO using sparse plasma concentration measurements. METHODS Previously developed population pharmacokinetic (PPK) models for olanzapine and risperidone were combined with a pharmacodynamic (PD) model for D2 RO and implemented in the R programming language. Maximum a posteriori (MAP) Bayesian estimation was used to provide predictions of plasma concentration and RO based on sparse concentration sampling. These predictions were then compared to observed plasma concentration and RO. RESULTS The average (standard deviation) response times of the tools, defined as the time required for the application to predict parameter values and display the output, were 2.8 (3.1) and 5.3 (4.3) seconds for olanzapine and risperidone, respectively. The mean error (95% confidence interval) and root mean squared error (RMSE, 95% CI) of predicted versus observed concentrations were 3.73 ng/mL (-2.42 - 9.87) and 10.816 ng/mL (6.71 - 14.93) for olanzapine, and 0.46 ng/mL (-4.56 - 5.47) and 6.68 ng/mL (3.57 - 9.78) for risperidone and its active metabolite (9-OH risperidone). Mean error and RMSE of RO were -1.47% (-4.65 - 1.69) and 5.80% (3.89 - 7.72) for olanzapine and -0.91% (-7.68 - 5.85) and 8.87% (4.56 - 13.17) for risperidone. CONCLUSION Our monitoring software predicts concentration-time profiles and the corresponding D2 RO from sparsely-sampled concentration measurements in an accessible and accurate form.
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Schizophrenia Research, 2019
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Case Reports in Psychiatry, 2019
Ehlers-Danlos syndrome (EDS) comprises a series of rare hereditary connective tissue diseases cha... more Ehlers-Danlos syndrome (EDS) comprises a series of rare hereditary connective tissue diseases characterized by musculoskeletal, skin, and cardiovascular involvements. EDS may be associated with physical as well as psychological pain that can lead to psychiatric problems. EDS imposes substantial psychological burden on patients, and recent large-scale studies have suggested that patients with EDS have a higher risk of mood disorders than the general population. To the best of our knowledge, we describe, for the first time, the cases of two Japanese patients with EDS complicated with mood disorders who secondarily developed transvestism that was judged strongly related to early stressful situations through childhood and adolescence. The first case was of a man in his mid-30s and the second of a woman in her late 20s. We report on detailed psychosocial data to further discuss the medical management and genetic counseling of such infrequent but challenging conditions. Physicians are adv...
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Journal of Affective Disorders, 2018
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Journal of Clinical Psychopharmacology, 2018
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European Psychiatry, 2017
Background:Health-related quality of life (HRQOL) is significantly affected in individuals with s... more Background:Health-related quality of life (HRQOL) is significantly affected in individuals with schizophrenia or bipolar I disorder (BD-I). The current study investigated whether symptomatic remission and resilience might differently impact HRQOL in these patients.Methods:Fifty-two patients with schizophrenia and 60 patients suffering from BD-I from outpatient mental health services as well as 77 healthy control subjects from the general community were included into a cross-sectional study. HRQOL and resilience were assessed using the WHOQOL-BREF and the Resilience Scale. In patients, psychopathology was quantified by the Positive and Negative Syndrome Scale or the Montgomery Asberg Depression Rating Scale and the Young Mania Rating Scale, respectively.Results:Notably, both patient groups showed lower HRQOL and resilience compared to control subjects, non-remitted patients indicated lower HRQOL than remitted ones. The effect of remission on HRQOL was significantly larger in patients...
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Schizophrenia Research, 2012
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Psychiatry and Clinical Neurosciences, 2011
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Journal of Psychiatric Research, 2011
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International Clinical Psychopharmacology, 2004
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European Psychiatry, 2006
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Molecular Psychiatry, Apr 20, 2022
Antipsychotic drugs are the mainstay in the treatment of schizophrenia. However, one-third of pat... more Antipsychotic drugs are the mainstay in the treatment of schizophrenia. However, one-third of patients do not show adequate improvement in positive symptoms with non-clozapine antipsychotics. Additionally, approximately half of them show poor response to clozapine, electroconvulsive therapy, or other augmentation strategies. However, the development of novel treatment for these conditions is difficult due to the complex and heterogenous pathophysiology of treatment-resistant schizophrenia (TRS). Therefore, this review provides key findings, potential treatments, and a roadmap for future research in this area. First, we review the neurobiological pathophysiology of TRS, particularly the dopaminergic, glutamatergic, and GABAergic pathways. Next, the limitations of existing and promising treatments are presented. Specifically, this article focuses on the therapeutic potential of neuromodulation, including electroconvulsive therapy, repetitive transcranial magnetic stimulation, transcranial direct current stimulation, and deep brain stimulation. Finally, we propose multivariate analyses that integrate various perspectives of the pathogenesis, such as dopaminergic dysfunction and excitatory/inhibitory imbalance, thereby elucidating the heterogeneity of TRS that could not be obtained by conventional statistics. These analyses can in turn lead to a precision medicine approach with closed-loop neuromodulation targeting the detected pathophysiology of TRS.
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Pharmacopsychiatry, Oct 27, 2015
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Papers by Takefumi Suzuki