A placebo-controlled study of the modafinil added to risperidone in chronic schizophrenia

Prodopaminergic Drugs for Treating the Negative Symptoms of Schizophrenia: Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

The negative symptoms of schizophrenia pose a heavy burden on patients and relatives and represent an unmet therapeutic need. The observed association of negative symptoms with impaired reward system function has stimulated research on prodopaminergic agents as potential adjunctive treatments.

METHODS

We conducted a systematic review and meta-analysis of published randomized controlled trials of amphetamine, methylphenidate, modafinil, armodafinil, lisdexamphetamine, L-dopa, levodopa, bromocriptine, cabergoline, quinagolide, lisuride, pergolide, apomorphine, ropinirole, pramipexole, piribedil, and rotigotine augmentation in schizophrenia and schizoaffective disorder.Medline, EMBASE, and several other databases as well as trial registries were searched for placebo-controlled trials.

RESULTS

Ten randomized controlled trials were included in the meta-analysis, 6 trials on modafinil, 2 on armodafinil, 1 on L-dopa, and 1 on pramipexole. Overall, prodopaminergic agents did not significantly reduce negative symptoms. Restricting the analysis to studies requiring a minimum threshold for negative symptom severity, modafinil/armodafinil showed a significant but small effect on negative symptoms. A subset of studies allowed for calculating specific effects for the negative symptom dimensions diminished expression and amotivation, but no significant effect was found. Prodopaminergic agents did not increase positive symptom scores.

CONCLUSIONS

The currently available evidence does not allow for formulating recommendations for the use of prodopaminergic agents for the treatment of negative symptoms. Nevertheless, the observed improvement in studies defining a minimum threshold for negative symptom severity in the absence of an increase in positive symptoms clearly supports further research on these agents.

Modafinil for people with schizophrenia or related disorders

BACKGROUND

People with schizophrenia have a range of different symptoms, including positive symptoms (hallucinations and delusions), negative symptoms (such as social withdrawal and lack of affect), and cognitive impairment. The standard medication for people with schizophrenia is antipsychotics. However, these medications may not be effective for all symptoms of schizophrenia, as cognitive and negative symptoms are usually hard to treat. Additional therapies or medications are available for the management of these symptoms. Modafinil, a wakefulness-promoting agent most frequently used in narcolepsy or shift work sleep disorder, is one intervention that is theorised to have an effect of these symptoms.

OBJECTIVES

The primary objective of this review was to assess the effects of modafinil for people with schizophrenia or related disorders.

SEARCH METHODS

On 27 April 2015, 24 May 2017, and 31 October 2019, we searched the Cochrane Schizophrenia Group's register of trials, which is based on regular searches of CENTRAL, MEDLINE, Embase, AMED, BIOSIS, CINAHL, PsycINFO, PubMed, and registries of clinical trials. There are no language, time, document type, or publication status limitations for the inclusion of records in the register.

SELECTION CRITERIA

We selected all randomised controlled trials comparing modafinil with placebo or other treatments for people with schizophrenia or schizophrenia-spectrum disorders.

DATA COLLECTION AND ANALYSIS

We independently extracted data from the included studies. We analysed dichotomous data using risk ratios (RR) and 95% confidence intervals (CI). We analysed continuous data using mean difference (MD) with a 95% CI. We used a random-effects model for the meta-analysis. We used GRADE to complete a 'Summary of findings' table and assessed risk of bias for the included studies.

MAIN RESULTS

Eleven studies including a total of 422 participants contributed to data analyses. Most studies had a small population size (average 38 people per study) and were of short duration. We also detected a high risk of bias for selective outcome reporting in just under 50% of the trials. We therefore rated the overall methodological quality of the included studies as low. We considered seven main outcomes of interest: clinically important change in overall mental state, clinically important change in cognitive functioning, incidence of a clinically important adverse effect/event, clinically important change in global state, leaving the study early for any reason, clinically important change in quality of life, and hospital admission. All studies assessed the effects of adding modafinil to participants' usual antipsychotic treatment compared to adding placebo to usual antipsychotic treatment. Six studies found that adding modafinil to antipsychotic treatment may have little or no effect on overall mental state of people with schizophrenia, specifically the risk of worsening psychosis (RR 0.91, 95% CI 0.28 to 2.98; participants = 209; studies = 6, low-quality evidence). Regarding the effect of modafinil on cognitive function, the trials did not report clinically important change data, but one study reported endpoint scores on the MATRICS Consensus Cognitive Battery (MCCB): in this study we found no clear difference in scores between modafinil and placebo treatment groups (MD -3.10, 95% CI -10.9 to 4.7; participants = 48; studies = 1, very low-quality evidence). Only one study (N = 35) reported adverse effect/event data. In this study one serious adverse event occurred in each group (RR 0.84, 95% CI 0.06 to 12.42; participants = 35; studies = 1, very low-quality evidence). One study measured change in global state using the Clinical Global Impression - Improvement Scale. This study found that adding modafinil to antipsychotic treatment may have little or no effect on global state (RR 6.36, 95% CI 0.94 to 43.07, participants = 21; studies = 1, very low-quality evidence). Nine studies found that modafinil has no effect on numbers of participants leaving the study early (RR 1.26, 95% CI 0.63 to 2.52 participants = 357; studies = 9, moderate-quality evidence). None of the trials reported clinically important change in quality of life, but one study did report quality of life using endpoint scores on the Quality of Life Inventory, finding no clear difference between treatment groups (MD -0.2, 95% CI -1.18 to 0.78; participants = 20; studies = 1, very low-quality evidence). Finally, one study reported data for number of participants needing hospitalisation: one participant in each group was hospitalised (RR 0.84, 95% CI 0.06 to 12.42; participants = 35; studies = 1, very low-quality evidence).

AUTHORS' CONCLUSIONS

Due to methodological issues, low sample size, and short duration of the clinical trials as well as high risk of bias for outcome reporting, most of the evidence available for this review is of very low or low quality. For results where quality is low or very low, we are uncertain or very uncertain if the effect estimates are true effects, limiting our conclusions. Specifically, we found that modafinil is no better or worse than placebo at preventing worsening of psychosis; however, we are uncertain about this result. We have more confidence that participants receiving modafinil are no more likely to leave a trial early than participants receiving placebo. However, we are very uncertain about the remaining equivocal results between modafinil and placebo for outcomes such as improvement in global state or cognitive function, incidence of adverse events, and changes in quality of life. More high-quality data are needed before firm conclusions regarding the effects of modafinil for people with schizophrenia or related disorders can be made.

Modafinil in schizophrenia: is the risk worth taking?

Schizophrenia is a severe mental disorder characterised by positive and negative symptoms. Negative symptoms are difficult to treat and there is no specific treatment. In small trials, modafinil has been studied in association with antipsychotic treatment. We present three cases of its use; two have developed positive symptoms and one developed renal impairment. Further studies are needed to assess its usefulness in schizophrenia and safety in this group of patients.

Antipsychotic augmentation with modafinil or armodafinil for negative symptoms of schizophrenia: systematic review and meta-analysis of randomized controlled trials

We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) of modafinil or armodafinil (ar/mod) augmentation in schizophrenia. We searched PubMed, clinical trial registries, reference lists, and other sources for parallel group, placebo-controlled RCTs. Our primary outcome variable was the effect of ar/mod on negative symptom outcomes. Eight RCTs (pooled N = 372; median duration, 8 weeks) met our selection criteria. Ar/mod (200 mg/day) significantly attenuated negative symptom ratings (6 RCTs; N = 322; standardized mean difference [SMD], -0.26; 95% CI, -0.48 to -0.04). This finding remained similar in all but one sensitivity analysis - when the only RCT in acutely ill patients was excluded, the outcome was no longer statistically significant (SMD, -0.17; 95% CI, -0.51 to 0.06). The absolute advantage for ar/mod was small: just 0.27 points on the PANSS-N (6 RCTs). Ar/mod attenuated total psychopathology ratings (7 RCTs; N = 342; SMD, -0.23; 95% CI, -0.45 to -0.02) but did not influence positive symptom ratings (5 RCTs; N = 302; mean difference, -0.58; 95% CI, -1.71 to 0.55). Although data were limited, cognition, fatigue, daytime drowsiness, adverse events, and drop out rates did not differ significantly between ar/mod and placebo groups. Fixed and random effects models yielded similar results. There was no heterogeneity in all but one analysis. Publication bias could not be tested. We conclude that ar/mod (200 mg/day) is safe and well tolerated in the short-term treatment of schizophrenia. Ar/mod reduces negative symptoms with a small effect size; the absolute advantage is also small, and the advantage disappears when chronically ill patients or those with high negative symptom burden are treated. Ar/mod does not benefit or worsen other symptom dimensions in schizophrenia.

Minocycline add-on to risperidone for treatment of negative symptoms in patients with stable schizophrenia: randomized double-blind placebo-controlled study

The objective of this study was to assess the efficacy and tolerability of minocycline add-on to risperidone in treatment of negative symptoms of patients with chronic schizophrenia. In a randomized double-blind placebo-controlled study, 40 patients with chronic schizophrenia who were stabilized on risperidone for a minimum duration of eight weeks were recruited. The patients were randomly assigned to minocycline (titrated up to 200 mg/day) or placebo in addition to risperidone (maximum dose of 6 mg/day) for eight weeks. Positive and Negative Syndrome Scale (PANSS), Hamilton Depression Rating Scale, and Extrapyramidal Syndrome Rating Scale were used. Thirty-eight patients completed the study. Significant time × treatment interaction for negative [F(2.254,85.638)=59.046, P<0.001] general psychopathology [F(1.703,64.700)=6.819, P=0.001], and positive subscales [F(1.655,62.878)=5.193, P=0.012] as well as total PANSS scores [F(1.677,63.720)=28.420, P<0.001] were observed. The strongest predictors for change in negative symptoms were the treatment group (β=-0.94, t=-10.59, P<0.001) followed by the change in PANSS positive subscale (β=-0.185, t=-2.075, P=0.045). Side effect profiles of the two treatment regimens were not significantly different. Minocycline seems to be an efficacious and tolerable short-term add-on to risperidone for treatment of negative and general psychopathology symptoms of schizophrenia.

Pharmacological approaches to treating negative symptoms: a review of clinical trials

Clinical trials of pharmacological agents targeting negative symptoms in schizophrenia are reviewed. The focus is on trials that occurred in patients who were stable on an antipsychotic medication at entry to the trial. A small number of trials compared antipsychotics as monotherapy for negative symptoms. Although the data supporting amisulpride for negative symptoms is promising the trials have limitations and it is plausible that the advantages of amisulpride over placebo may result from effects on secondary negative symptoms. Among available agents, antidepressant medications may have effects in negative symptoms. Other promising agents include minocycline, glutamatergic agents, and alpha-7 nicotinic agents. More than 15 active trials are currently underway to evaluate new treatments for negative symptoms.

Modafinil improves antipsychotic-induced parkinsonism but not excessive daytime sleepiness, psychiatric symptoms or cognition in schizophrenia and schizoaffective disorder: a randomized, double-blind, placebo-controlled study

OBJECTIVE

To examine the efficacy and safety of modafinil on parkinsonism and excessive daytime sleepiness (EDS), as well as on negative symptoms and cognitive abilities in patients with schizophrenia or schizoaffective disorder (DSM-IV criteria) in a randomized double-blind placebo-controlled 8-week study.

METHODS

Twenty-four male patients, who were aged 20-63 years and on stable dose of second generation antipsychotic medications and with a negative symptom score of ≥ 20 on the Positive and Negative Syndrome Scale (PANSS), were randomized into either the modafinil (n=12) or placebo (n=12) group. The modafinil group received flexible does of modafinil 50-200mg/day. Primary measurements were the Simpson-Angus Scale (SAS) for extrapyramidal side effects (EPS), the Epworth Sleepiness Scale (ESS), the PANSS and a neuropsychological (NP) test battery. Data were collected on Days 0, 14, 28, 42 and 56 for rating scales, and on Days 0, 28 and 56 for NP tests.

RESULTS

Mixed model analyses showed a significant group-x-time interaction for total SAS scores (P<0.006), with scores decreasing in the modafinil group but remaining the same in the placebo group. There were no significant group-x-time interactions for scores of ESS (total), PANSS (total, positive and negative), and NP tests (composite and domains) (all P's>0.5). No significant adverse events were observed.

CONCLUSION

The data suggest that modafinil was a safe adjunctive treatment which improved parkinsonian symptoms and signs in patients with schizophrenia or schizoaffective disorder. Further studies in larger samples and with longer study time are needed to test/confirm the beneficial effects of modafinil on motor function.

A placebo-controlled study of tropisetron added to risperidone for the treatment of negative symptoms in chronic and stable schizophrenia

RATIONAL

A growing body of evidence illustrates that 5-HT3 receptor antagonist drugs may be of benefit in the treatment of negative symptoms in schizophrenia.

OBJECTIVE

The objective of this study was to assess the efficacy and tolerability of tropisetron add-on to risperidone on negative symptoms in patients with chronic stable schizophrenia.

METHODS

In a double-blind, placebo-controlled 8-week trial, 40 patients with chronic schizophrenia who were stabilized on risperidone were randomized into tropisetron or placebo add-on groups. Psychotic symptoms were measured using the Positive and Negative Syndrome Scale (PANSS) every 2 weeks. Furthermore, extrapyramidal and depressive symptoms as well as side effects were assessed. The primary outcome measure was the difference in change from baseline of negative subscale scores between the two groups at week 8.

RESULTS

Tropisetron resulted in greater improvement of the total PANSS scores [F(1.860,70.699) = 37.366, p < 0.001] as well as negative scores [F(2.439,92.675) = 16.623, p < 0.001] and general psychopathology [F(1.767,67.158) = 4.602, p = 0.017], but not positive subscale scores [F(1.348, 51.218) = 0.048, p = 0.893] compared to placebo. In a multiple regression analysis controlling for positive, extrapyramidal, and depressive symptoms, treatment group (standardized β = -0.640) significantly predicted changes in primary negative symptoms. The side effect profile did not differ significantly between the two groups.

CONCLUSION

Tropisetron add-on to risperidone improves the primary negative symptoms of patients with chronic stable schizophrenia.

A systematic review of psychostimulant treatment of negative symptoms of schizophrenia: challenges and therapeutic opportunities

BACKGROUND

Primary negative symptoms of schizophrenia (NSS) contribute heavily to functional disability and treatment of these symptoms continues to be a major unmet need even when the positive (psychotic) symptoms are controlled. The modified dopamine (DA) hypothesis posits that positive symptoms are associated with increased DA activity in the mesolimbic tract whereas NSS and cognitive symptoms are associated with decreased DA activity in the mesocortical (frontal) region. Several studies have reported improvement in NSS with DA agonist use, but with varying degrees of risk for triggering psychotic symptoms, especially in the absence of concurrent antipsychotic drug treatment. This article aims to examine older and newer evidence suggesting that psychostimulants may have a potential therapeutic role in the treatment of NSS together with a thorough review of the potential risks and benefits of psychostimulant administration in individuals with schizophrenia.

METHODS

A systematic search of relevant literature using electronic databases, reference lists, and data presented at recent meetings was conducted.

RESULTS

Improvement of NSS after psychostimulant administration is reviewed both in challenge and treatment paradigms with various agents such as methylphenidate, amphetamine, and modafinil or armodafinil. The literature points to evidence that, used adjunctively, DA agonists may improve NSS without worsening of positive symptoms in selected patients who are stable and treated with effective antipsychotic medications. Several areas of inadequate study and limitations are identified including small study samples, single-site trials, varying rigor of bias control, the dose and the duration of adjunctive psychostimulant administration, and the potential for development of tolerance.

CONCLUSION

Large, controlled clinical trials to further characterize effects of psychostimulants on NSS in carefully selected patients are warranted.

Two subdomains of negative symptoms in psychotic disorders: established and confirmed in two large cohorts

Negative symptoms of schizophrenia are normally grouped into a single category. However, the diversity of such symptoms suggests that they are actually made up of more than one dimension. The DSM-V proposes two negative symptom domains, namely expressive deficits and avolition/asociality. We investigated whether the negative symptoms do indeed have two dimensions. An exploratory factor analysis was carried out based on interviews with the PANSS (664 patients). We restricted our analysis to items that had been described as negative symptoms in previous factor analyses. The symptom structure was then tested for stability by performing a confirmatory factor analysis on PANSS interviews from a separate cohort (2172 patients). Exploratory factor analysis yielded a two-factor structure of negative symptoms. The first factor consisted of PANSS items Flat affect, Poor rapport, Lack of spontaneity, Mannerisms and posturing, Motor retardation, and Avolition. The second factor consisted of Emotional withdrawal, Passive/apathetic social withdrawal, and Active social avoidance. The first factor could be related to expressive deficits, reflecting a loss of initiative, and the second factor to social amotivation, related to community interaction. This factor structure supports the DSM-V classification and may be relevant for pathophysiology and treatment of schizophrenia and other psychotic disorders.

Newer antipsychotics and upcoming molecules for schizophrenia

BACKGROUND

The management of schizophrenia has seen significant strides over the last few decades, due to the increasing availability of a number of antipsychotics. Yet, the diminished efficacy in relation to the negative and cognitive symptoms of schizophrenia, and the disturbing adverse reactions associated with the current antipsychotics, reflect the need for better molecules targeting unexplored pathways.

PURPOSE

To review the salient features of the recently approved antipsychotics; namely, iloperidone, asenapine, lurasidone and blonanserin.

METHODS

We discuss the advantages, limitations and place in modern pharmacotherapy of each of these drugs. In addition, we briefly highlight the new targets that are being explored.

RESULTS

Promising strategies include modulation of the glutamatergic and GABAergic pathways, as well as cholinergic systems.

CONCLUSIONS

Although regulatory bodies have approved only a handful of antipsychotics in recent years, the wide spectrum of targets that are being explored could eventually bring out antipsychotics with improved efficacy and acceptability, as well as the potential to revolutionize psychiatric practice.

Modafinil effects on cognition and emotion in schizophrenia and its neurochemical modulation in the brain

Modafinil is a central nervous system wake promoting agent used for the treatment of excessive daytime sleeping. Its vigilance promoting properties and low abuse potential has intrigued the scientific community and has led to use it as a cognitive enhancer, before its neural functions were understood. Here, we review the effects of modafinil in human cognition and emotion and its specific actions on symptoms in patients with schizophrenia and whether these are consistently effective throughout the literature. We also performed a systematic review on the effects of modafinil on neurotransmitter signalling in different areas of the brain in order to better understand the neuromechanisms of its cognitive and emotional enhancing properties. A review of its effects in schizophrenia suggests that modafinil facilitates cognitive functions, with pro-mnemonic effects and problem solving improvements. Emotional processing also appears to be enhanced by the drug, although to date there are only a limited number of studies. The systematic review on the neurochemical modulation of the modafinil suggests that its mnemonic enhancing properties might be the result of glutamatergic and dopaminergic increased neuronal activation in the hippocampus and in the prefrontal cortex respectively. Other neurotransmitters were also activated by modafinil in various limbic brain areas, suggesting that the drug acts on these brain regions to influence emotional responses. These reviews seek to delineate the neuronal mechanisms by which modafinil affects cognitive and emotional function. This article is part of a Special Issue entitled 'Cognitive Enhancers'.