The benefit of minocycline on negative symptoms of schizophrenia in patients with recent-onset psychosis (BeneMin): a randomised, double-blind, placebo-controlled trial

An update on the efficacy of anti-inflammatory agents for patients with schizophrenia: a meta-analysis

BACKGROUND

Accumulating evidence shows that a propensity towards a pro-inflammatory status in the brain plays an important role in schizophrenia. Anti-inflammatory drugs might compensate this propensity. This study provides an update regarding the efficacy of agents with some anti-inflammatory actions for schizophrenia symptoms tested in randomized controlled trials (RCTs).

METHODS

PubMed, Embase, the National Institutes of Health website (http://www.clinicaltrials.gov), and the Cochrane Database of Systematic Reviews were systematically searched for RCTs that investigated clinical outcomes.

RESULTS

Our search yielded 56 studies that provided information on the efficacy of the following components on symptom severity: aspirin, bexarotene, celecoxib, davunetide, dextromethorphan, estrogens, fatty acids, melatonin, minocycline, N-acetylcysteine (NAC), pioglitazone, piracetam, pregnenolone, statins, varenicline, and withania somnifera extract. The results of aspirin [mean weighted effect size (ES): 0.30; n = 270; 95% CI (CI) 0.06-0.54], estrogens (ES: 0.78; n = 723; CI 0.36-1.19), minocycline (ES: 0.40; n = 946; CI 0.11-0.68), and NAC (ES: 1.00; n = 442; CI 0.60-1.41) were significant in meta-analysis of at least two studies. Subgroup analysis yielded larger positive effects for first-episode psychosis (FEP) or early-phase schizophrenia studies. Bexarotene, celecoxib, davunetide, dextromethorphan, fatty acids, pregnenolone, statins, and varenicline showed no significant effect.

CONCLUSIONS

Some, but not all agents with anti-inflammatory properties showed efficacy. Effective agents were aspirin, estrogens, minocycline, and NAC. We observed greater beneficial results on symptom severity in FEP or early-phase schizophrenia.

Adjunctive minocycline for major mental disorders: A systematic review

OBJECTIVES

This meta-analysis of randomized controlled trials (RCTs) examined the efficacy and safety of minocycline for three major mental disorders: schizophrenia, bipolar disorder and major depressive disorder (MDD).

METHODS

A systematic literature search of major electronic databases was conducted. Meta-analysis of clinical efficacy as defined by the respective studies, all-cause discontinuation, adverse drug reactions (ADRs) with standardized mean difference (SMD) and risk ratios (RRs) and their 95% confidence intervals (CI) was conducted using random-effects model. Quality assessment was performed with the Jadad scale and Cochrane risk of bias.

RESULTS

Sixteen RCTs (n=1357) on minocycline (50-300 mg/day) for schizophrenia (13 RCTs, n=1196), bipolar depression (1 RCT, n=49), and MDD (2 RCTs, n=112) were analyzed separately by diagnosis. Twelve RCTs mentioned randomized allocation specifically; the weighted Jadad scores were 4.0. Adjunctive minocycline outperformed placebo in improving total psychopathology [SMD: -0.45 (95%CI: -0.73, -0.16), p=0.002; I²=77%], positive [SMD: -0.15 (95%CI: -0.28, -0.02), p=0.02; I²=0%], negative [SMD: -0.62 (95%CI: -0.95, -0.28), p=0.0003; I²=85%] and general psychopathology scores [SMD: -0.28 (95%CI: -0.53, -0.03), p=0.03; I²=59%] in schizophrenia. Minocycline showed no significant effect on depressive and manic symptoms in both bipolar depression and MDD. Minocycline caused significantly less headache (p=0.02, number-needed-to-harm=14, 95%CI=5-14) than placebo in schizophrenia. All-cause discontinuation and other ADRs were similar between minocycline and placebo in each diagnostic category.

CONCLUSION

In this meta-analysis, adjunctive minocycline appeared to be efficacious and safe for schizophrenia. However, the efficacy of adjunctive minocycline for bipolar depression or MDD could not be demonstrated.

REVIEW REGISTRATION

PROSPERO: CRD42018102483.

Minocycline alters behavior, microglia and the gut microbiome in a trait-anxiety-dependent manner

Major depressive disorder is the main cause of disability worldwide with imperfect treatment options. However, novel therapeutic approaches are currently discussed, from augmentation strategies to novel treatments targeting the immune system or the microbiome-gut-brain axis. Therefore, we examined the potential beneficial effects of minocycline, a tetracycline antibiotic with pleiotropic, immunomodulatory action, alone or as augmentation of escitalopram on behavior, prefrontal microglial density, and the gut microbiome in rats selectively bred for high anxiety-like behavior (HAB). We show that concomitant with their high innate anxiety and depression, HABs have lower microglial numbers in the infralimbic and prelimbic prefrontal cortex and an altered gut microbiota composition compared with controls. Three weeks of minocycline treatment alleviated the depressive-like phenotype, further reduced microglial density, exclusively in male HAB rats, and reduced plasma concentrations of pro-inflammatory cytokines. However, coadministration of escitalopram, which had no effect alone, prevented these minocycline-induced effects. Moreover, minocycline led to a robust shift in cecal microbial composition in both HABs and rats non-selected for anxiety-like behavior. Minocycline markedly increased relative abundance of Lachnospiraceae and Clostridiales Family XIII, families known for their butyrate production, with a corresponding increase and positive correlation in plasma 3-OH-butyrate levels in a trait-dependent manner. Thus, our data suggest that the antidepressant effect of minocycline is sex- and trait-dependent, associated with a reduced microglial number in the prefrontal cortex, and with changes in microbial composition and their metabolites. These results further support the microbiome-gut-brain axis as potential target in the treatment of depression.

Antipsychotics: Mechanisms underlying clinical response and side-effects and novel treatment approaches based on pathophysiology

Antipsychotic drugs are central to the treatment of schizophrenia and other psychotic disorders but are ineffective for some patients and associated with side-effects and nonadherence in others. We review the in vitro, pre-clinical, clinical and molecular imaging evidence on the mode of action of antipsychotics and their side-effects. This identifies the key role of striatal dopamine D2 receptor blockade for clinical response, but also for endocrine and motor side-effects, indicating a therapeutic window for D2 blockade. We consider how partial D2/3 receptor agonists fit within this framework, and the role of off-target effects of antipsychotics, particularly at serotonergic, histaminergic, cholinergic, and adrenergic receptors for efficacy and side-effects such as weight gain, sedation and dysphoria. We review the neurobiology of schizophrenia relevant to the mode of action of antipsychotics, and for the identification of new treatment targets. This shows elevated striatal dopamine synthesis and release capacity in dorsal regions of the striatum underlies the positive symptoms of psychosis and suggests reduced dopamine release in cortical regions contributes to cognitive and negative symptoms. Current drugs act downstream of the major dopamine abnormalities in schizophrenia, and potentially worsen cortical dopamine function. We consider new approaches including targeting dopamine synthesis and storage, autoreceptors, and trace amine receptors, and the cannabinoid, muscarinic, GABAergic and glutamatergic regulation of dopamine neurons, as well as post-synaptic modulation through phosphodiesterase inhibitors. Finally, we consider treatments for cognitive and negative symptoms such dopamine agonists, nicotinic agents and AMPA modulators before discussing immunological approaches which may be disease modifying. This article is part of the issue entitled 'Special Issue on Antipsychotics'.

Neuroinflammation and Schizophrenia

PURPOSE OF REVIEW

There are longstanding, intriguing findings of immune dysfunction in schizophrenia. These findings span peripheral immune markers, especially cytokine abnormalities.

RECENT FINDINGS

This review describes recent genetic and immune marker studies and emergent treatment studies. Collectively, this provides a synthesis and current appraisal of the neuroimmune hypothesis of schizophrenia.

Treating psychiatric symptoms and disorders with non-psychotropic medications

A few drugs prescribed in internal medicine, ie, non-psychotropic drugs, can be used to treat certain neuropsychiatric disorders. For most of these situations, the level of evidence remains low. But when sufficient data becomes available, these molecules are then included in official guidelines for the treatment of neuropsychiatric disorders. In this article we review interesting drugs which may be relevant from an evidence-based medicine point of view, and could become part of psychiatric practice in the future.


Catatonia and the immune system: a review

Catatonia is a psychomotor disorder featuring stupor, posturing, and echophenomena. This Series paper examines the evidence for immune dysregulation in catatonia. Activation of the innate immune system is associated with mutism, withdrawal, and psychomotor retardation, which constitute the neurovegetative features of catatonia. Evidence is sparse and conflicting for acute-phase activation in catatonia, and whether this feature is secondary to immobility is unclear. Various viral, bacterial, and parasitic infections have been associated with catatonia, but it is primarily linked to CNS infections. The most common cause of autoimmune catatonia is N-methyl-D-aspartate receptor (NMDAR) encephalitis, which can account for the full spectrum of catatonic features. Autoimmunity appears to cause catatonia less by systemic inflammation than by the downstream effects of specific actions on extracellular antigens. The specific association with NMDAR encephalitis supports a hypothesis of glutamatergic hypofunction in catatonia.

Galantamine-Memantine Combination as an Antioxidant Treatment for Schizophrenia

PURPOSE OF REVIEW

The objective of this article is to highlight the potential role of the galantamine-memantine combination as a novel antioxidant treatment for schizophrenia.

RECENT FINDINGS

In addition to the well-known mechanisms of action of galantamine and memantine, these medications also have antioxidant activity. Furthermore, an interplay exists between oxidative stress, inflammation (redox-inflammatory hypothesis), and kynurenine pathway metabolites. Also, there is an interaction between brain-derived neurotrophic factor and oxidative stress in schizophrenia. Oxidative stress may be associated with positive, cognitive, and negative symptoms and impairments in white matter integrity in schizophrenia. The antipsychotic-galantamine-memantine combination may provide a novel strategy in schizophrenia to treat positive, cognitive, and negative symptoms.

SUMMARY

A "single antioxidant" may be inadequate to counteract the complex cascade of oxidative stress. The galantamine-memantine combination as "double antioxidants" is promising. Hence, randomized controlled trials are warranted with the antipsychotic-galantamine-memantine combination with oxidative stress and antioxidant biomarkers in schizophrenia.

The effect of minocycline on symptoms in schizophrenia: Results from a randomized controlled trial

BACKGROUND

Studies have hypothesized that immunological abnormalities might contribute to schizophrenia, and basic science studies, as well as several clinical trials suggest that minocycline could be efficacious in ameliorating both positive and negative symptoms of schizophrenia. In this study we examined the effect of minocycline on schizophrenia in a large randomized controlled trial.

METHODS

We performed a 16-week, multi-center, double-blind, randomized, placebo-controlled study on 200 subjects with schizophrenia or schizoaffective disorder randomized to receive either minocycline (200 mg/day, n = 100), or placebo (n = 100) as an add-on to anti-psychotic treatment. The primary outcome measure was the PANSS total score.

RESULTS

Mixed models for repeated measures showed no significant difference between minocycline and placebo for total PANSS (p = 0.862), PANSS subscales, CGI or BACS.

CONCLUSIONS

Minocycline did not improve symptoms or cognition in schizophrenia.

Antipsychotic-minocycline-acetylcysteine combination for positive, cognitive, and negative symptoms of schizophrenia

Preclinical evidence shows that the minocycline and N-acetylcysteine (NAC) combination synergistically improved cognition. Meta-analyses of randomized controlled trials (RCTs) with minocycline and NAC have shown some efficacy signal for positive, cognitive, and negative symptoms of schizophrenia. Hence, the combination may be more effective than either medication alone. The objective of this article is to highlight the potential role of the minocycline-NAC combination for the treatment of schizophrenia. The antipsychotic-minocycline-NAC combination is promising and has the potential to concurrently treat positive, cognitive, and primary negative symptoms. RCTs are warranted with the minocycline-NAC combination to address the unmet clinical need in schizophrenia.

Inflammation, Antipsychotic Drugs, and Evidence for Effectiveness of Anti-inflammatory Agents in Schizophrenia

In recent years, there is a new optimism in schizophrenia therapeutics with the emergence of immunomodulation as a potential treatment approach. Current evidence points to various immunological abnormalities in schizophrenia, including cell-mediated processes, acute phase proteins, cytokines, and intracellular mediators. Trait- and state-related immune dysfunction appears to exist, and a strong case can therefore be made for immunomodulation therapies in the prevention, treatment, and/or moderating the course of schizophrenia.Immunomodulation approaches include use of nonsteroidal anti-inflammatory agents to stop or moderate an over-activated inflammatory process, anti-oxidants, nutrients, vitamins, herbal products, and other neuroprotection agents that inhibit pro-inflammatory processes, optimal use of antipsychotic drugs (APDs) that may have anti-inflammatory actions or in certain cases such as clozapine may enhance blunted inflammatory responses, and biological agents to antagonize specific immune mediators such as the cytokines. A combination of two or more of the above approaches is also worthy of consideration.In this chapter, the available data for each of the above approaches is reviewed and discussed. Strengths and limitations of current studies are identified, and suggestions are made for future studies. For example, identifying patients with high levels of specific biomarkers such as C-Reactive Protein, IL-6, IFN-γ, TNF-α, and genetic polymorphisms of cytokines, and match them with clinical subgroups such as prodromal, first episode psychosis, chronic psychosis, and negative symptoms with the aim of developing targeted treatment approaches and more personalized medicine. Meanwhile, since the science and trial data are not advanced enough to make definitive recommendations, clinicians should stay up to date with the literature, obtain detailed immunological histories, and review the risk-benefit ratio of adding available immune modulating agents to standard therapies, to provide optimal and state-of-the-art care to patients.

Cytokines, Oxidative Stress and Cellular Markers of Inflammation in Schizophrenia

In this article, we review current evidence linking immune dysfunction in schizophrenia and related psychotic disorders focusing particularly on circulating cytokines, oxidative stress and cellular markers of inflammation in various stages on illness from drug-naïve first episode psychosis to chronic schizophrenia. Acute psychotic episode is associated with low-grade systemic inflammation in some patients, as reflected by increased concentrations of cytokines and other inflammatory markers in peripheral blood. Evidence from general population-based longitudinal cohort studies reporting an association between elevated inflammatory markers in childhood/adolescence and risk of schizophrenia and related psychosis subsequently in adulthood suggest that inflammation could be a causal risk factor for psychosis rather than simply be a consequence of illness. Mendelian randomization studies also suggest that associations between IL-6, CRP and schizophrenia are likely to be causal. In addition, we discuss evidence for disruptions in oxidative stress markers and CSF cytokine levels in schizophrenia, and potential reasons for reported trans-diagnostic associations for inflammatory cytokines including role of early-life adversity/maltreatment. We argue that low-grade inflammation is a clinically useful feature, because it is associated with poor response to antipsychotic medication in first episode psychosis. We discuss clinical implications for immunological understanding of schizophrenia including scope for clinical trials of anti-inflammatory agents and notable gaps in current knowledge, and offer suggestions for future research.

The benefit of minocycline on negative symptoms of schizophrenia in patients with recent-onset psychosis (BeneMin): a randomised, double-blind, placebo-controlled trial

BACKGROUND

The antibiotic minocycline has neuroprotective and anti-inflammatory properties that could prevent or reverse progressive neuropathic changes implicated in recent-onset schizophrenia. In the BeneMin study, we aimed to replicate the benefit of minocycline on negative symptoms reported in previous pilot studies, and to understand the mechanisms involved.

METHODS

In this randomised, double-blind, placebo-controlled trial, we recruited people with a schizophrenia-spectrum disorder that had begun within the past 5 years with continuing positive symptoms from 12 National Health Service (NHS) trusts. Participants were randomly assigned according to an automated permuted blocks algorithm, stratified by pharmacy, to receive minocycline (200 mg per day for 2 weeks, then 300 mg per day for the remainder of the 12-month study period) or matching placebo, which were added to their continuing treatment. The primary clinical outcome was the negative symptom subscale score of the Positive and Negative Syndrome Scales (PANSS) across follow-ups at months 2, 6, 9, and 12. The primary biomarker outcomes were medial prefrontal grey-matter volume, dorsolateral prefrontal cortex activation during a working memory task, and plasma concentration of interleukin 6. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN49141214, and the EU Clinical Trials register (EudraCT) number is 2010-022463-35I.

FINDINGS

Between April 16, 2013, and April 30, 2015, we recruited 207 people and randomly assigned them to receive minocycline (n=104) or placebo (n=103). Compared with placebo, the addition of minocycline had no effect on ratings of negative symptoms (treatment effect difference -0·19, 95% CI -1·23 to 0·85; p=0·73). The primary biomarker outcomes did not change over time and were not affected by minocycline. The groups did not differ in the rate of serious adverse events (n=11 in placebo group and n=18 in the minocycline group), which were mostly due to admissions for worsening psychiatric state (n=10 in the placebo group and n=15 in the minocycline group). The most common adverse events were gastrointestinal (n=12 in the placebo group, n=19 in the minocycline group), psychiatric (n=16 in placebo group, n=8 in minocycline group), nervous system (n=8 in the placebo group, n=12 in the minocycline group), and dermatological (n=10 in the placebo group, n=8 in the minocycline group).

INTERPRETATION

Minocycline does not benefit negative or other symptoms of schizophrenia over and above adherence to routine clinical care in first-episode psychosis. There was no evidence of a persistent progressive neuropathic or inflammatory process underpinning negative symptoms. Further trials of minocycline in early psychosis are not warranted until there is clear evidence of an inflammatory process, such as microgliosis, against which minocycline has known efficacy.

FUNDING

National Institute for Health Research Efficacy and Mechanism Evaluation (EME) programme, an MRC and NIHR partnership.

Constructing the Immune Signature of Schizophrenia for Clinical Use and Research; An Integrative Review Translating Descriptives Into Diagnostics

Schizophrenia is considered a syndrome comprised by several disease phenotypes, covering a range of underlying pathologies. One of these disease mechanisms seems to involve immune dysregulation and neuroinflammation. While the current dopamine receptor-blocking antipsychotic drugs decrease psychotic symptoms and prevent relapse in the majority of patients with schizophrenia, there is a huge need to explore new treatment options that target other pathophysiological pathways. Such studies should aim at identifying robust biomarkers in order to diagnose and monitor the immune biophenotype in schizophrenia and develop better selection procedures for clinical trials with anti-inflammatory and immune-modulating drugs. In this focused review, we describe available methods to assess inflammatory status and immune disturbances in vivo. We also outline findings of immune disturbances and signs of inflammation at cellular, protein, and brain imaging levels in patients with schizophrenia. Furthermore, we summarize the results from studies with anti-inflammatory or other immune-modulating drugs, highlighting how such studies have dealt with participant selection. Finally, we propose a strategy to construct an immune signature that may be helpful in selecting and monitoring participants in studies with immune modulating drugs and also applicable in regular clinical work.