Meta-Analysis of Efficacy of Mirtazapine as an Adjunctive Treatment of Negative Symptoms in Schizophrenia

Mirtazapine in schizophrenia - an undeservedly overlooked option?

Mirtazapine has often been prescribed as add-on treatment for schizophrenia in patients with suboptimal response to conventional treatments. In this review, we evaluate the existing evidence for efficacy and effectiveness of add-on mirtazapine in schizophrenia and reappraise the practical and theoretical aspects of mirtazapine-antipsychotic combinations. In randomized controlled trials (RCTs), mirtazapine demonstrated favourable effects on negative and cognitive (although plausibly not depressive) symptoms, with no risk of psychotic exacerbation. Mirtazapine also may have a desirable effect on antipsychotic-induced sexual dysfunction, but seems not to alleviate extrapyramidal symptoms, at least if combined with second-generation antipsychotics. It is noteworthy that all published RCTs have been underpowered and relatively short in duration. In the only large pragmatic effectiveness study that provided analyses by add-on antidepressant, only mirtazapine was associated with both decreased rate of hospital admissions and number of in-patient days. Mirtazapine hardly affects the pharmacokinetics of antipsychotics. However, possible pharmacodynamic interactions (sedation and metabolic offence) should be borne in mind. The observed desired clinical effects of mirtazapine may be due to its specific receptor-blocking properties. Alternative theoretical explanations include its possible neuroprotective effect. Further well-designed RCTs and real-world effectiveness studies are needed to determine whether add-on mirtazapine should be recommended for difficult-to-treat schizophrenia.

Negative symptoms of psychosis: A life course approach and implications for prevention and treatment

AIM

Negative symptoms are a cause of enduring disability in serious mental illness. In spite of this, the development of effective treatments for negative symptoms has remained slow. The challenge of improving negative symptom outcomes is compounded by our limited understanding of their aetiology and longitudinal development.

METHODS

A literature search was conducted for life course approach of negative symptoms using PubMed. Further articles were included following manual checking of reference lists and other search strategies. The paper contains a theoretical synthesis of the literature, summarized using conceptual models.

RESULTS

Negative symptom definitions are compared and considered within a context of the life course. Previous studies suggest that several illness phases may contribute to negative symptoms, highlighting our uncertainty in relation to the origin of negative symptoms.

CONCLUSIONS

Similar to other aspects of schizophrenia, negative symptoms likely involve a complex interplay of several risk and protective factors at different life phases. Concepts suggested in this article, such as "negative symptom reserve" theory, require further research, which may inform future prevention and treatment strategies.

Mirtazapine adjunct for people with schizophrenia

BACKGROUND

Many individuals who have a diagnosis of schizophrenia experience a range of distressing and debilitating symptoms. These can include positive symptoms (such as delusions, hallucinations, disorganised speech), cognitive symptoms (such as trouble focusing or paying attention or using information to make decisions), and negative symptoms (such as diminished emotional expression, avolition, alogia, and anhedonia). Antipsychotic drugs are often only partially effective, particularly in treating negative symptoms, indicating the need for additional treatment. Mirtazapine is an antidepressant drug that when taken in addition to an antipsychotic may offer some benefit for negative symptoms.

OBJECTIVES

To systematically assess the effects of mirtazapine as adjunct treatment for people with schizophrenia.

SEARCH METHODS

The Information Specialist of Cochrane Schizophrenia searched the Cochrane Schizophrenia Group's Study-Based Register of Trials (including registries of clinical trials) up to May 2018.

SELECTION CRITERIA

All randomised-controlled trials (RCTs) with useable data focusing on mirtazapine adjunct for people with schizophrenia.

DATA COLLECTION AND ANALYSIS

We extracted data independently. For binary outcomes, we calculated risk ratio (RR) and its 95% confidence interval (CI), on an intention-to-treat (ITT) basis. For continuous data, we estimated the mean difference (MD) between groups and its 95% CI. We employed a fixed-effect model for analyses. For included studies we assessed risk of bias and created 'Summary of findings' table using GRADE.

MAIN RESULTS

We included nine RCTs with a total of 310 participants. All studies compared mirtazapine adjunct with placebo adjunct and were of short-term duration. We considered five studies to have a high risk of bias for either incomplete outcome data, selective reporting, or other bias.Our main outcomes of interest were clinically important change in mental state (negative and positive symptoms), leaving the study early for any reason, clinically important change in global state, clinically important change in quality of life, number of days in hospital and incidence of serious adverse events.One trial defined a reduction in the Scale for the Assessment of Negative Symptoms (SANS) overall score from baseline of at least 20% as no important response for negative symptoms. There was no evidence of a clear difference between the two treatments with similar numbers of participants from each group showing no important response to treatment (RR 0.81, 95% CI 0.57 to 1.14, 1 RCT, n = 20, very low-quality evidence).Clinically important change in positive symptoms was not reported, however, clinically important change in overall mental state was reported by two trials and data for this outcome showed a favourable effect for mirtazapine (RR 0.69, 95% CI 0.51 to 0.92; I² = 75%, 2 RCTs, n = 77, very low-quality evidence). There was no evidence of a clear difference for numbers of participants leaving the study early (RR 1.03, 95% CI 0.64 to 1.66, 9 RCTs, n = 310, moderate-quality evidence), and no evidence of a clear difference in global state Clinical Global Impressions Scale (CGI) severity scores (MD -0.10, 95% CI -0.68 to 0.48, 1 RCT, n = 39, very low-quality evidence). A favourable effect for mirtazapine adjunct was found for the outcome clinically important change in akathisia (RR 0.33, 95% CI 0.20 to 0.52, 2 RCTs, n = 86, low-quality evidence; I² = 61%I). No data were reported for quality life or number of days in hospital.In addition to the main outcomes of interest, there was evidence relating to adverse events that the mirtazapine adjunct groups were associated with an increased risk of weight gain (RR 3.19, 95% CI 1.17 to 8.65, 4 RCTs, n = 127) and sedation/drowsiness (RR 1.64, 95% CI 1.01 to 2.68, 7 RCTs, n = 223).

AUTHORS' CONCLUSIONS

The available evidence is primarily of very low quality and indicates that mirtazapine adjunct is not clearly associated with an effect for negative symptoms, but there is some indication of a positive effect on overall mental state and akathisia. No effect was found for global state or leaving the study early and data were not available for quality of life or service use. Due to limitations of the quality and applicability of the evidence it is not possible to make any firm conclusions, the role of mirtazapine adjunct in routine clinical practice remains unclear. This underscores the need for new high-quality evidence to further evaluate mirtazapine adjunct for schizophrenia.

Antidepressant Controlled Trial For Negative Symptoms In Schizophrenia (ACTIONS): a double-blind, placebo-controlled, randomised clinical trial

BACKGROUND

Negative symptoms of schizophrenia represent deficiencies in emotional responsiveness, motivation, socialisation, speech and movement. When persistent, they are held to account for much of the poor functional outcomes associated with schizophrenia. There are currently no approved pharmacological treatments. While the available evidence suggests that a combination of antipsychotic and antidepressant medication may be effective in treating negative symptoms, it is too limited to allow any firm conclusions.

OBJECTIVE

To establish the clinical effectiveness and cost-effectiveness of augmentation of antipsychotic medication with the antidepressant citalopram for the management of negative symptoms in schizophrenia.

DESIGN

A multicentre, double-blind, individually randomised, placebo-controlled trial with 12-month follow-up.

SETTING

Adult psychiatric services, treating people with schizophrenia.

PARTICIPANTS

Inpatients or outpatients with schizophrenia, on continuing, stable antipsychotic medication, with persistent negative symptoms at a criterion level of severity.

INTERVENTIONS

Eligible participants were randomised 1 : 1 to treatment with either placebo (one capsule) or 20 mg of citalopram per day for 48 weeks, with the clinical option at 4 weeks to increase the daily dosage to 40 mg of citalopram or two placebo capsules for the remainder of the study.

MAIN OUTCOME MEASURES

The primary outcomes were quality of life measured at 12 and 48 weeks assessed using the Heinrich's Quality of Life Scale, and negative symptoms at 12 weeks measured on the negative symptom subscale of the Positive and Negative Syndrome Scale.

RESULTS

No therapeutic benefit in terms of improvement in quality of life or negative symptoms was detected for citalopram over 12 weeks or at 48 weeks, but secondary analysis suggested modest improvement in the negative symptom domain, avolition/amotivation, at 12 weeks (mean difference -1.3, 95% confidence interval -2.5 to -0.09). There were no statistically significant differences between the two treatment arms over 48-week follow-up in either the health economics outcomes or costs, and no differences in the frequency or severity of adverse effects, including corrected QT interval prolongation.

LIMITATIONS

The trial under-recruited, partly because cardiac safety concerns about citalopram were raised, with the 62 participants recruited falling well short of the target recruitment of 358. Although this was the largest sample randomised to citalopram in a randomised controlled trial of antidepressant augmentation for negative symptoms of schizophrenia and had the longest follow-up, the power of statistical analysis to detect significant differences between the active and placebo groups was limited.

CONCLUSION

Although adjunctive citalopram did not improve negative symptoms overall, there was evidence of some positive effect on avolition/amotivation, recognised as a critical barrier to psychosocial rehabilitation and achieving better social and community functional outcomes. Comprehensive assessment of side-effect burden did not identify any serious safety or tolerability issues. The addition of citalopram as a long-term prescribing strategy for the treatment of negative symptoms may merit further investigation in larger studies.

FUTURE WORK

Further studies of the viability of adjunctive antidepressant treatment for negative symptoms in schizophrenia should include appropriate safety monitoring and use rating scales that allow for evaluation of avolition/amotivation as a discrete negative symptom domain. Overcoming the barriers to recruiting an adequate sample size will remain a challenge.

TRIAL REGISTRATION

European Union Drug Regulating Authorities Clinical Trials (EudraCT) number 2009-009235-30 and Current Controlled Trials ISRCTN42305247.

FUNDING

This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 20, No. 29. See the NIHR Journals Library website for further project information.

The Role of Genes, Stress, and Dopamine in the Development of Schizophrenia

The dopamine hypothesis is the longest standing pathoetiologic theory of schizophrenia. Because it was initially based on indirect evidence and findings in patients with established schizophrenia, it was unclear what role dopamine played in the onset of the disorder. However, recent studies in people at risk of schizophrenia have found elevated striatal dopamine synthesis capacity and increased dopamine release to stress. Furthermore, striatal dopamine changes have been linked to altered cortical function during cognitive tasks, in line with preclinical evidence that a circuit involving cortical projections to the striatum and midbrain may underlie the striatal dopamine changes. Other studies have shown that a number of environmental risk factors for schizophrenia, such as social isolation and childhood trauma, also affect presynaptic dopaminergic function. Advances in preclinical work and genetics have begun to unravel the molecular architecture linking dopamine, psychosis, and psychosocial stress. Included among the many genes associated with risk of schizophrenia are the gene encoding the dopamine D2 receptor and those involved in the upstream regulation of dopaminergic synthesis, through glutamatergic and gamma-aminobutyric acidergic pathways. A number of these pathways are also linked to the stress response. We review these new lines of evidence and present a model of how genes and environmental factors may sensitize the dopamine system so that it is vulnerable to acute stress, leading to progressive dysregulation and the onset of psychosis. Finally, we consider the implications for rational drug development, in particular regionally selective dopaminergic modulation, and the potential of genetic factors to stratify patients.

Treating Negative Symptoms in Schizophrenia: an Update

Interest in the negative symptoms of schizophrenia has increased rapidly over the last several decades, paralleling a growing interest in functional, in addition to clinical, recovery, and evidence underscoring the importance negative symptoms play in the former. Efforts continue to better define and measure negative symptoms, distinguish their impact from that of other symptom domains, and establish effective treatments as well as trials to assess these. Multiple interventions have been the subject of investigation, to date, including numerous pharmacological strategies, brain stimulation, and non-somatic approaches. Level and quality of evidence vary considerably, but to this point, no specific treatment can be recommended. This is particularly problematic for individuals burdened with negative symptoms in the face of mild or absent positive symptoms. Presently, clinicians will sometimes turn to interventions that are seen as more “benign” and in line with routine clinical practice. Strategies include use of atypical antipsychotics, ensuring the lowest possible antipsychotic dose that maintains control of positive symptoms (this can involve a shift from antipsychotic polypharmacy to monotherapy), possibly an antidepressant trial (given diagnostic uncertainty and the frequent use of these drugs in schizophrenia), and non-somatic interventions (e.g., cognitive behavioral therapy, CBT). The array and diversity of strategies currently under investigation highlight the lack of evidence-based treatments and our limited understanding regarding negative symptoms underlying etiology and pathophysiology. Their onset, which can precede the first psychotic break, also means that treatments are delayed. From this perspective, identification of biomarkers and/or endophenotypes permitting earlier diagnosis and intervention may serve to improve treatment efficacy as well as outcomes.

Association between antipsychotic/antidepressant drug treatments and hospital admissions in schizophrenia assessed using a mental health case register

Background:

The impact of psychotropic drug choice upon admissions for schizophrenia is not well understood.

Aims:

To examine the association between antipsychotic/antidepressant use and time in hospital for patients with schizophrenia.

Methods:

We conducted an observational study, using 8 years’ admission records and electronically generated drug histories from an institution providing secondary mental health care in Cambridgeshire, UK, covering the period 2005–2012 inclusive. Patients with a coded ICD-10 diagnosis of schizophrenia were selected. The primary outcome measure was the time spent as an inpatient in a psychiatric unit. Antipsychotic and antidepressant drugs used by at least 5% of patients overall were examined for associations with admissions. Periods before and after drug commencement were compared for patients having pre-drug admissions, in mirror-image analyses correcting for overall admission rates. Drug use in one 6-month calendar period was used to predict admissions in the next period, across all patients, in a regression analysis accounting for the effects of all other drugs studied and for time.

Results:

In mirror-image analyses, sulpiride, aripiprazole, clozapine, and olanzapine were associated with fewer subsequent admission days. In regression analyses, sulpiride, mirtazapine, venlafaxine, and clozapine–aripiprazole and clozapine–amisulpride combinations were associated with fewer subsequent admission days.

Conclusions:

Use of these drugs was associated with fewer days in hospital. Causation is not implied and these findings require confirmation by randomized controlled trials.

Pharmacological treatment of negative symptoms in schizophrenia

Effective treatment of negative symptoms is one of the most important unmet needs in schizophrenic disorders. Because the evidence on current psychopharmacological treatments is unclear, the authors reviewed the findings published to date by searching PubMed with the keywords negative symptoms, antipsychotics, antidepressants, glutamatergic compounds, monotherapy and add-on therapy and identifying additional articles in the reference lists of the resulting publications. The findings presented here predominantly focus on results of meta-analyses. Evidence for efficacy of current psychopharmacological medications is difficult to assess because of methodological problems and inconsistent results. In general, the second-generation antipsychotics (SGAs) do not appear to have good efficacy in negative symptoms, although some show better efficacy than first-generation antipsychotics, some of which also demonstrated efficacy in negative symptoms. Specific trials on predominant persistent negative symptoms are rare and have been performed with only a few SGAs. More often, trials on somewhat persistent negative symptoms evaluate add-on strategies to ongoing antipsychotic treatment. Such trials, mostly on modern antidepressants, have demonstrated some efficacy. Several trials with small samples have evaluated add-on treatment with glutamatergic compounds, such as the naturally occurring amino acids glycine and D-serine and new pharmacological compounds. The results are highly inconsistent, although overall efficacy results appear to be positive. The unsatisfactory and inconsistent results can be partially explained by methodological problems. These problems need to be solved in the future, and the authors propose some possible solutions. Further research is required to identify effective treatment for the negative symptoms of schizophrenia.

α2-Adrenoceptors are targets for antipsychotic drugs

RATIONALE

Almost all antipsychotic drugs (APDs), irrespective of whether they belong to the first-generation (e.g. haloperidol) or second-generation (e.g. clozapine), are dopamine D2 receptor antagonists. Second-generation APDs, which differ from first-generation APDs in possessing a lower propensity to induce extrapyramidal side effects, target a variety of monoamine receptors such as serotonin (5-hydroxytryptamine) receptors (e.g. 5-HT1A, 5-HT2A, 5-HT2C, 5-HT6, 5-HT7) and α1- and α2-adrenoceptors in addition to their antagonist effects at D2 receptors.

OBJECTIVE

This short review is focussed on the potential role of α2-adrenoceptors in the antipsychotic therapy.

RESULTS

Schizophrenia is characterised by three categories of symptoms: positive symptoms, negative symptoms and cognitive deficits. α2-Adrenoceptors are classified into three distinct subtypes in mammals, α2A, α2B and α2C. Whereas the α2B-adrenoceptor seems to play only a minor role in the brain, activation of postsynaptic α2A-adrenoceptors in the prefrontal cortex improves cognitive functions. Preclinical models such as D-amphetamine-induced locomotion, the conditioned avoidance response and the pharmacological N-methyl-D-aspartate receptor hypofunction model have shown that α2C-adrenoceptor blockade or the combination of D2 receptor antagonists with idazoxan (α2A/2C-adrenoceptor antagonist) could be useful in schizophrenia. A potential benefit of a treatment combination of first-generation APDs with the α2A/2C-adrenoceptor antagonists idazoxan or mirtazapine was also demonstrated in patients with schizophrenia.

CONCLUSIONS

It is concluded that α2-adrenoceptors may be promising targets in the antipsychotic therapy.