Integrated dopaminergic neuronal model with reduced intracellular processes and inhibitory autoreceptors

Dopamine (DA) is an important neurotransmitter for multiple brain functions, and dysfunctions of the dopaminergic system are implicated in neurological and neuropsychiatric disorders. Although the dopaminergic system has been studied at multiple levels, an integrated and efficient computational model that bridges from molecular to neuronal circuit level is still lacking. In this study, the authors aim to develop a realistic yet efficient computational model of a dopaminergic pre‐synaptic terminal. They first systematically perturb the variables/substrates of an established computational model of DA synthesis, release and uptake, and based on their relative dynamical timescales and steady‐state changes, approximate and reduce the model into two versions: one for simulating hourly timescale, and another for millisecond timescale. They show that the original and reduced models exhibit rather similar steady and perturbed states, whereas the reduced models are more computationally efficient and illuminate the underlying key mechanisms. They then incorporate the reduced fast model into a spiking neuronal model that can realistically simulate the spiking behaviour of dopaminergic neurons. In addition, they successfully include autoreceptor‐mediated inhibitory current explicitly in the neuronal model. This integrated computational model provides the first step toward an efficient computational platform for realistic multiscale simulation of dopaminergic systems in in silico neuropharmacology

Declining efficacy in controlled trials of antidepressants: effects of placebo dropout

Contains fulltext : 136241.pdf (publisher's version ) (Open Access)Drug-placebo differences (effect-sizes) in controlled trials of antidepressants for major depressive episodes have declined for several decades, in association with selectively increasing clinical improvement associated with placebo-treatment. As these trends require adequate explanation, we tested the hypothesis that decreasing trial-dropout rates may be an important contributor. We gathered reports of peer-reviewed, placebo-controlled trials of antidepressants (1980-2011) by computerized literature searching, and applied meta-analysis, meta-regression and multiple linear regression methods to evaluate associations of dropout rates and other factors of interest, to reporting year and reported efficacy [standardized mean drug-placebo difference (SMD) as Hedges' g-statistic]. In 56 trials meeting inclusion and exclusion criteria, we confirmed significant overall efficacy of antidepressants but declining drug-placebo contrasts over the past three decades. Among other changes, there was a corresponding increase in placebo-associated improvement with a decline in placebo-dropout rate, mainly for lack of efficacy. These effects were found only when last-observation-carried-forward (LOCF) analyses were used. Other trial-design and subject factors, including drug-responses and drug-dropout rates, were much less associated with efficacy. We propose that declining placebo-dropout rates ascribed to inefficacy combined with use of LOCF analyses led to increasing improvement in placebo-arms that contributed to declining antidepressant-placebo contrasts in controlled treatment trials since the 1980s

Treatments for acute bipolar depression: meta-analyses of placebo-controlled, monotherapy trials of anticonvulsants, lithium and antipsychotics

Item does not contain fulltextBACKGROUND: Optimal treatments for bipolar depression, and the relative value of specific drugs for that purpose, remain uncertain, including agents other than antidepressants. METHODS: We searched for reports of placebo-controlled, monotherapy trials of mood-stabilizing anticonvulsants, second-generation antipsychotics, or lithium for acute major depressive episodes in patients diagnosed with type I or II bipolar disorder and applied random-effects meta-analysis to evaluate their efficacy, comparing outcomes based on standardized mean drug-placebo differences (SMD) in improvement, relative response rates (RR), and number-needed-to-treat (NNT). RESULTS: We identified 24 trials of 10 treatments (lasting 7.5 weeks, with >/= 50 collaborating sites/trial) that met eligibility criteria: lamotrigine (5 trials), quetiapine (5), valproate (4), 2 each for aripiprazole, olanzapine, ziprasidone, and 1 each for carbamazepine, lithium, lurasidone, and olanzapine-fluoxetine. Overall, pooled drug-over-placebo responder-rate superiority (RR) was moderate (29% [CI: 19-40%]), and NNT was 8.2 (CI: 6.4-11). By SMD, apparent efficacy ranked: olanzapine + fluoxetine >/= valproate > quetiapine > lurasidone > olanzapine, aripiprazole, and carbamazepine; ziprasidone was ineffective, and lithium remains inadequately studied. Notably, drugs were superior to placebo in only 11/24 trials (5/5 with quetiapine, 2/4 with valproate), and only lamotrigine, quetiapine and valproate had > 2 trials. Treatment-associated mania-like reactions were uncommon (drugs: 3.7%; placebo: 4.7%). DISCUSSION: Controlled trials of non-antidepressant treatments for bipolar depression remain scarce, but findings with olanzapine-fluoxetine, lurasidone, quetiapine, and perhaps carbamazepine and valproate were encouraging; lithium requires adequate testing

Duration of initial antidepressant treatment and subsequent relapse of major depression

10.1097/JCP.0000000000000263Journal of Clinical Psychopharmacology35175-7

Supplementary Material for: Systematic Review of Blinding Assessment in Randomized Controlled Trials in Schizophrenia and Affective Disorders 2000-2010

<b><i>Background:</i></b> Blinding is an integral part of many randomized controlled trials (RCTs). However, both blinding and blinding assessment seem to be rarely documented in trial reports. <b><i>Method:</i></b> Systematic review of articles on RCTs in schizophrenia and affective disorders research during 2000-2010. <b><i>Results:</i></b> Among 2,467 publications, 61 (2.5%; 95% confidence interval: 1.9-3.1%) reported assessing participant, rater, or clinician blinding: 5/672 reports on schizophrenia (0.7%; 0.3-1.6%) and 33/1,079 (3.1%; 2.1-4.2%) on affective disorders, without significant trends across the decade. Rarely was blinding assessed at the beginning, in most studies assessment was at the end. Proportion of patients' and raters' correct guesses of study arm averaged 54.4 and 62.0% per study, with slightly more correct guesses in treatment arms than in placebo arms. Three fourths of responders correctly guessed that they received the active agent. Blinding assessment was more frequently reported in papers on psychotherapy and brain stimulation than on drug trials (5.1%, 1.7-11.9%, vs. 8.3%, 4.3-14.4%, vs. 2.1%, 1.5-2.8%). Lack of assessment of blinding was associated with: (a) positive findings, (b) full industrial sponsorship, and (c) diagnosis of schizophrenia. There was a moderate association of treatment success and blinding status of both trial participants (r = 0.51, p = 0.002) and raters (r = 0.55, p = 0.067). Many RCT reports did not meet CONSORT standards regarding documentation of persons blinded (60%) or of efforts to match interventions (50%). <b><i>Conclusions:</i></b> Recent treatment trials in major psychiatric disorders rarely reported on or evaluated blinding. We recommend routine documentation of blinding strategies in reports

Multiple Versus Single Antipsychotic Agents for Hospitalized Psychiatric Patients: Case-Control Study of Risks Versus Benefits.

Objective: Since use of multiple drugs to treat psychiatric patients is increasing, and research on this practice is rare, the authors carried out a retrospective case-control study of multiple versus single antipsychotic treatment in psychiatric inpatients. Method: Inpatient treatment groups receiving either antipsychotic monotherapy or polytherapy were matched in terms of age, sex, diagnostic category, and admission clinical ratings (Global Assessment of Functioning [GAF] and Clinical Global Impression [CGI]), which yielded 70 subject pairs. They were compared in terms of total chlorpromazine-equivalent daily dose, changes in total daily dose, length of hospitalization, incidence of adverse effects, and changes in clinical ratings (CGI,GAF, Positive and Negative Syndrome Scale score) between admission and discharge. Results: Initial doses were closely similar at admission for both treatment groups, but the median total final antipsychotic dose was 78% higher for those receiving antipsychotic polytherapy versus monotherapy. Also, median length of stay in the hospital was 55% (8.5 days) longer, and risk of adverse effects was 56% higher with polytherapy, whereas clinical improvement scores were similar (within 11%) for both treatments. Conclusions: Short-term treatment with multiple antipsychotics was associated with major increases in drug exposure, adverse events, and time in the hospital but with no apparent gain in clinical benefit. These findings require further testing in controlled prospective studies

Prospective, Open Study of Long-Acting Injected Risperidone versus Oral Antipsychotics in 88 Chronically Psychotic Patients

Introduction: A long-acting, injected, carbohydrate-microsphere preparation of risperidone (RLAI; Risperdal Consta (R)) is reported to be safe and effective in chronic psychotic illnesses but, as its long-term and comparative efficacy remain unclear, this study compared clinical status during oral antipsychotic treatment versus conversion to RLAI. Methods: Psychotic patients (n = 88; initial BPRS = 93 +/- 5) were treated for 6 months with clinically chosen oral medication and then converted to biweekly RLAI for the first 6 months (6-6 months matched mirror comparison) and then for another 18 months. Clinical status in the two treatment periods and in the 18 months of follow-up was compared with measures including BPRS improvement (primary outcome), CGI variants and SF-36 ratings. Results: RLAI (at a mean dose of 47 mg/2 weeks at six and up to 23.1 +/- 3.3 months) was associated with major improvements in all outcome measures (p < 0.001). Initial BPRS scores fell by an average of 50% within six months; hospitalizations declined from 19.8% to 0%, and rates of adverse events were reduced by 2.5- to 7.4-fold. Such benefits were sustained during 18 months of follow-up with RLAI-treatment. Conclusions: The findings are limited by the lack of a parallel control treatment, such as with oral risperidone or another antipsychotic, lack of blinded assessments, and a moderate number of subjects. Nevertheless, the findings add to indications that RLAI can be an effective and well-tolerated treatment-option for chronically psychotic patients