Qualitative methods in early-phase drug trials: broadening the scope of data and methods from an RCT of N-acetylcysteine in schizophrenia

Mixed Methods Thematic Analysis of a Randomised Controlled Trial of Adjunctive Mitochondrial Agents for Bipolar Depression

Objective

There is often a shortfall in recovery following treatment for an episode of bipolar disorder (BD). Exploration of participant's experience provides vital information to enhance statistical outcomes for novel therapy trials. This study used mixed-methods to explore participants' experience of a trial testing N -acetyl cysteine (NAC) and mitochondrially active nutraceuticals for BD depression.

Methods

Case

report forms from a randomised controlled trial (RCT) of BD depression (n = 148) were analysed using a pragmatic adaption of grounded theory and thematic analysis.

Results

Thematic analysis of 148 study participants indicated numerous changes in participant experience over time. For example, perceived environmental stressors reported by participants decreased over the trial in both treatment groups. Quantitative analysis of the themes revealed more positive theme reports in the combination treatment arm compared to the placebo arm and there were more negative themes identified in the placebo arm, compared to the NAC arm.

Conclusion

This approach revealed additional results not elucidated in the primary quantitative analysis. This emphasises the value of mixed-methods research in capturing participants' experiences in RCTs and detecting possible latent benefits and risks. Such methods can detect latent target signals in novel therapy trials conducted in BD and generate novel hypotheses.

Effect of N-acetyl cysteine (NAC) supplementation on positive and negative syndrome scale in schizophrenia: a systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

To conduct a systematic review and meta-analysis of published randomised controlled trials on the efficacy of NAC supplementation on positive and negative syndrome scale in schizophrenia.

METHODS

A meta-analysis was conducted, and studies were identified by a search of electronic databases from inception to May 2018. Combined and stratified analyses were used.

RESULTS

Seven trials were identified, and data from n = 447 participants were included. Pooled analysis showed improvement of positive and negative syndrome scale following NAC treatment compared with placebo, for total (SMB = - 0.96) [95% CI - 1.69, - 0.24; P = 0.009], general (SMB = - 1.04) [95% CI - 1.80, - 0.27; P = 0.008] and negative (SMB = - 0.73) [95% CI - 1.29, - 0.17; P = 0.01] scores, respectively. Significant heterogeneity was found, and subgroup analysis showed significant reductions in studies with a treatment duration of ≤ 24 weeks, with a considerable effect size on total, general, and negative scores (Total SMD = - 0.83; General SMD = - 0.67; Negative SMD = - 1.09) following NAC.

CONCLUSIONS

NAC improved all aspects of positive and negative syndrome scale in schizophrenic populations and may be more efficacious with treatment durations up to 24 weeks.

Therapeutic effect of adjunctive N-acetyl cysteine (NAC) on symptoms of chronic schizophrenia: A double-blind, randomized clinical trial

BACKGROUND

Schizophrenia is one of the most disabling psychiatric syndromes with the prevalence of 1% in the general population. Despite availability of various antipsychotics, negative symptoms and cognitive impairment are difficult to treat. In addition antipsychotic monotherapy is not effective in most of these patients. Current evidence indicates the roles of glutamatergic system in this disorder. N-acetyl cysteine (NAC) also increases extracellular glutamate. This study was conducted to evaluate the clinical effects of oral NAC as an add-on to maintenance medication for the treatment of chronic schizophrenia.

MATERIALS AND METHODS

This 12-week, double-blind, randomized, placebo-controlled, clinical trial was performed to determine the effectiveness of 1200mg N-acetyl cysteine as an adjunctive treatment with conventional antipsychotic medications in 84 patients with chronic schizophrenia. The subjects were evaluated with the Positive and Negative Syndrome Scale (PANSS), Mini-Mental State Examination (MMSE), and a standard neuropsychological screening test. Data were analyzed with SPSS-16 software.

RESULTS

NAC-treated patients showed significantly improvement in the positive (F=5.47, P=0.02) and negative (F=0.20, df=1) PANSS subscale. Also the general and total PANSS score of NAC group declined over times whilst it was increased for placebo group. Regarding cognitive functions, improvement was observed in some explored areas, such as attention, short-term and working memory, executive functioning and speed of processing. There was no significant difference between the 2 groups in the frequency of adverse effects.

CONCLUSION

The present study detected improvement in positive, negative, general and total psychopathology symptoms as well as cognitive performance with NAC treatment. It is also well-tolerated, safe and easy-to-use agent as an effective therapeutic strategy to improve outcome in schizophrenia treatment.

MATERNAL PERCEPTIONS OF PARENTING FOLLOWING AN EVIDENCE-BASED PARENTING PROGRAM: A QUALITATIVE STUDY OF LEGACY FOR CHILDRENTM

This article presents the findings of a qualitative study of maternal perceptions of parenting following participation in Legacy for ChildrenTM (Legacy), an evidence-based parenting program for low-income mothers of young children and infants. To further examine previous findings and better understand participant experiences, we analyzed semistructured focus-group discussions with predominantly Hispanic and Black, non-Hispanic Legacy mothers at two sites (n = 166) using thematic analysis and grounded theory techniques. The qualitative study presented here investigated how mothers view their parenting following participation in Legacy, allowing participants to describe their experience with the program in their own words, thus capturing an "insider" perspective. Mothers at both sites communicated knowledge and use of positive parenting practices targeted by the goals of Legacy; some site-specific differences emerged related to these parenting practices. These findings align with the interpretation of quantitative results from the randomized controlled trials and further demonstrate the significance of the Legacy program in promoting positive parenting for mothers living in poverty. This study emphasizes the importance of understanding real-world context regarding program efficacy and the benefit of using qualitative research to understand participant experiences.

Cognitive effects of adjunctive N-acetyl cysteine in psychosis

BACKGROUND

Cognitive deficits are predictors of functional outcome in patients with psychosis. While conventional antipsychotics are relatively effective on positive symptoms, their impact on negative and cognitive symptoms is limited. Recent studies have established a link between oxidative stress and neurocognitive deficits in psychosis. N-acetylcysteine (NAC), a glutathione precursor with glutamatergic properties, has shown efficacy on negative symptoms and functioning in patients with schizophrenia and bipolar disorder, respectively. However, there are few evidence-based approaches for managing cognitive impairment in psychosis. The present study aims to examine the cognitive effects of adjunctive NAC treatment in a pooled subgroup of participants with psychosis who completed neuropsychological assessment in two trials of both schizophrenia and bipolar disorder.

METHOD

A sample of 58 participants were randomized in a double fashion to receive 2 g/day of NAC (n = 27) or placebo (n = 31) for 24 weeks. Attention, working memory and executive function domains were assessed. Differences between cognitive performance at baseline and end point were examined using Wilcoxon's test. The Mann-Whitney test was used to examine the differences between the NAC and placebo groups at the end point.

RESULTS

Participants treated with NAC had significantly higher working memory performance at week 24 compared with placebo (U = 98.5, p = 0.027).

CONCLUSIONS

NAC may have an impact on cognitive performance in psychosis, as a significant improvement in working memory was observed in the NAC-treated group compared with placebo; however, these preliminary data require replication. Glutamatergic compounds such as NAC may constitute a step towards the development of useful therapies for cognitive impairment in psychosis.

N-acetylcysteine in the treatment of psychiatric disorders: current status and future prospects

INTRODUCTION

N-acetylcysteine (NAC) is widely known for its role as a mucolytic and as an antidote to paracetamol overdose. There is increasing interest in the use of NAC in the treatment of several psychiatric disorders. The rationale for the administration of NAC in psychiatric conditions is based on its role as a precursor to the antioxidant glutathione, and its action as a modulating agent of glutamatergic, dopaminergic, neurotropic and inflammatory pathways. Areas covered: This study reviews the available data regarding the use of NAC in different psychiatric disorders including substance use disorders, autism, obsessive-compulsive spectrum disorders, schizophrenia, depression, bipolar disorder. Promising results were found in trials testing the use of NAC, mainly as an add-on treatment, in cannabis use disorder in young people, depression in bipolar disorder, negative symptoms in schizophrenia, and excoriation (skin-picking) disorder. Despite initial optimism, recent findings regarding NAC efficacy in autism have been disappointing. Expert opinion: These preliminary positive results require further confirmation in larger samples and with longer follow-ups. Given its high tolerability and wide availability, NAC represents an important target to investigate in the field of new adjunctive treatments for psychiatric conditions.

Clinical trials of N-acetylcysteine in psychiatry and neurology: A systematic review

N-acetylcysteine (NAC) is recognized for its role in acetaminophen overdose and as a mucolytic. Over the past decade, there has been growing evidence for the use of NAC in treating psychiatric and neurological disorders, considering its role in attenuating pathophysiological processes associated with these disorders, including oxidative stress, apoptosis, mitochondrial dysfunction, neuroinflammation and glutamate and dopamine dysregulation. In this systematic review we find favorable evidence for the use of NAC in several psychiatric and neurological disorders, particularly autism, Alzheimer's disease, cocaine and cannabis addiction, bipolar disorder, depression, trichotillomania, nail biting, skin picking, obsessive-compulsive disorder, schizophrenia, drug-induced neuropathy and progressive myoclonic epilepsy. Disorders such as anxiety, attention deficit hyperactivity disorder and mild traumatic brain injury have preliminary evidence and require larger confirmatory studies while current evidence does not support the use of NAC in gambling, methamphetamine and nicotine addictions and amyotrophic lateral sclerosis. Overall, NAC treatment appears to be safe and tolerable. Further well designed, larger controlled trials are needed for specific psychiatric and neurological disorders where the evidence is favorable.

Towards stage specific treatments: effects of duration of illness on therapeutic response to adjunctive treatment with N-acetyl cysteine in schizophrenia

Schizophrenia is a chronic and often debilitating disorder in which stage of illness appears to influence course, outcome, prognosis and treatment response. Current evidence suggests roles for oxidative, neuroinflammatory, neurotrophic, apoptotic, mitochondrial and glutamatergic systems in the disorder; all targets of N-acetyl cysteine (NAC). A double blind, placebo controlled trial suggested NAC to be beneficial to those diagnosed with schizophrenia. The current manuscript aims to investigate duration of the illness as a key factor that may be modulating the response to NAC in the participants who took part in the study. A sample of 121 participants were randomised in a double fashion to 24 weeks (placebo=62; NAC=59). Clinical and functional variables were collected over the treatment period. Duration of the illness at baseline was grouped into <10 years, 10-<20 years and >20 years. Mixed Model Repeated Measures Analysis was used to explore the effect of illness duration on response to treatment with NAC. A significant interaction between duration of the illness and response to treatment with NAC was consistently found for positive symptoms and functional variables, but not for negative or general symptoms or for side effect related outcomes. The pattern of changes suggests that this mediator effect of duration of illness in response to treatment is more evident in those participants with 20 years or more of illness duration. Our results suggest a potential advantage of adjunctive NAC over placebo on functioning and positive symptoms reduction in those patients with chronic schizophrenia. This has potential for suggesting stage specific treatments.

Design and rationale of a 16-week adjunctive randomized placebo-controlled trial of mitochondrial agents for the treatment of bipolar depression

OBJECTIVE

Bipolar disorder places a significant burden on individuals, caregivers and family, and the broader community. Current treatments are believed to be more effective against manic symptoms, leaving a shortfall in recovery during the depressive phase of the illness. The current study draws on recent evidence suggesting that, in addition to increased oxidative load, alterations in mitochondrial function occur in bipolar disorder.

METHODS

This 16-week study aims to explore the potential benefits of N-acetylcysteine (NAC) alone or in combination (CT) with selected nutraceuticals believed to enhance mitochondrial function. The study includes adults diagnosed with bipolar disorder currently experiencing an episode of depression. Participants are asked to take NAC, CT, or placebo in addition to any usual treatments. A post-discontinuation visit is conducted 4 weeks following the treatment phase.

RESULTS

The primary outcome of the study will be mean change on the Montgomery-Asberg Depression Rating Scale. Secondary outcomes include functioning, substance use, mania ratings, and quality of life. Blood samples will be collected at baseline and week 16 to explore biochemical alterations following treatment.

CONCLUSION

This study may provide a novel adjunctive treatment for bipolar depression. Analysis of biological samples may assist in understanding the therapeutic benefits and the underlying etiology of bipolar depression.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trial Registry ACTRN12612000830897.

Neuroprogression in schizophrenia: Pathways underpinning clinical staging and therapeutic corollaries

OBJECTIVE

Whilst dopaminergic dysfunction remains a necessary component involved in the pathogenesis of schizophrenia, our current pharmacological armoury of dopamine antagonists does little to control the negative symptoms of schizophrenia. This suggests other pathological processes must be implicated. This paper aims to elaborate on such theories.

METHODS

Data for this review were sourced from the electronic database PUBMED, and was not limited by language or date of publication.

RESULTS

It has been suggested that multiple 'hits' may be required to unveil the clinical syndrome in susceptible individuals. Such hits potentially first occur in utero, leading to neuronal disruption, epigenetic changes and the establishment of an abnormal inflammatory response. The development of schizophrenia may therefore potentially be viewed as a neuroprogressive response to these early stressors, driven on by changes in tryptophan catabolite (TRYCAT) metabolism, reactive oxygen species handling and N-methyl d-aspartate (NMDA) circuitry. Given the potential for such progression over time, it is prudent to explore the new treatment strategies which may be implemented before such changes become established.

CONCLUSIONS

Outside of the dopaminergic model, the potential pathogenesis of schizophrenia has yet to be fully elucidated, but common themes include neuropil shrinkage, the development of abnormal neuronal circuitry, and a chronic inflammatory state which further disrupts neuronal function. Whilst some early non-dopaminergic treatments show promise, none have yet to be fully studied in appropriately structured randomized controlled trials and they remain little more than potential attractive targets.

Addressing the unmet needs of patients with persistent negative symptoms of schizophrenia: emerging pharmacological treatment options

The negative symptoms of schizophrenia represent an impairment of normal emotional responses, thought processes and behaviors, and include blunting or flattening of affect, alogia/aprosody, avolition/apathy, anhedonia, and asociality. Negative symptoms contribute to a reduced quality of life, increased functional disability, increased burden of illness, and poorer long-term outcomes, to a greater degree than positive symptoms. Primary negative symptoms are prominent and persistent in up to 26% of patients with schizophrenia, and they are estimated to occur in up to 58% of outpatients at any given time. Negative symptoms respond less well to medications than positive symptoms, and to date treatment options for negative symptoms have been limited, with no accepted standard treatment. Modest benefits have been reported with a variety of different agents, including second-generation antipsychotics and add-on therapy with antidepressants and other pharmacological classes. Recent clinical research focusing on negative symptoms target novel biological systems, such as glutamatergic neurotransmission. Different approaches include: enhancing N-methyl-D-aspartate receptor function with agents that bind directly to the glycine ligand site or with glycine reuptake inhibitors; influencing the metabotropic glutamate receptor (mGluR2/3) with positive allosteric modulators; and stimulating nicotinic acetylcholine receptors. In conclusion, the lack of clearly efficacious pharmacological treatments for the management of negative symptoms represents a significant unmet need, especially considering the importance of these symptoms on patient outcomes. Hence, further research to identify and characterize novel pharmacological treatments for negative symptoms is greatly needed.

Glutamate-based anxiolytic ligands in clinical trials

INTRODUCTION

With regard to anxiety, the role of the balance between glutamatergic and GABAergic systems was pursued for many years. The majority of drugs used presently as effective anxiolytics enhance the GABAergic system activity, thus increasing inhibition within the central nervous system (CNS). On the other hand, decreasing the activity of glutamatergic neurotransmission may attenuate excitation in the CNS, thus resulting in anxiolysis.

AREAS COVERED

The present review focuses on clinical data of well-known and recently discovered glutamatergic and, to a lesser extent, GABAergic agents, which reached at least the Phase II criteria.

EXPERT OPINION

A variety of glutamatergic agents active at both N-acetylo-D-asparaginian and metabotropic glutamate (mGlu) receptors have been tested in humans to examine their potential anxiolytic activity. Many compounds acting on the glutamatergic system and approved for the treatment of other disorders than anxiety were shown to exert anxiolytic effects in clinical trials. Those are mainly voltage-dependent ion channel ligands as well as d-cycloserin and memantine. Also, ligands active at mGlu receptors, such as fenobam and LY354740, exhibited activity in controlled clinical trials. However, relatively few trials are found on the agents that are focused on GABAergic neurotransmission. Therefore, it seems that glutamatergic system may become a novel target for modern and effective anxiolytics.

Reduction in phencyclidine induced sensorimotor gating deficits in the rat following increased system xc⁻ activity in the medial prefrontal cortex

RATIONALE

Aspects of schizophrenia, including deficits in sensorimotor gating, have been linked to glutamate dysfunction and/or oxidative stress in the prefrontal cortex. System xc(-), a cystine-glutamate antiporter, is a poorly understood mechanism that contributes to both cellular antioxidant capacity and glutamate homeostasis.

OBJECTIVES

Our goal was to determine whether increased system xc(-) activity within the prefrontal cortex would normalize a rodent measure of sensorimotor gating.

METHODS

In situ hybridization was used to map messenger RNA (mRNA) expression of xCT, the active subunit of system xc(-), in the prefrontal cortex. Prepulse inhibition was used to measure sensorimotor gating; deficits in prepulse inhibition were produced using phencyclidine (0.3-3 mg/kg, sc). N-Acetylcysteine (10-100 μM) and the system xc(-) inhibitor (S)-4-carboxyphenylglycine (CPG, 0.5 μM) were used to increase and decrease system xc(-) activity, respectively. The uptake of (14)C-cystine into tissue punches obtained from the prefrontal cortex was used to assay system xc(-) activity.

RESULTS

The expression of xCT mRNA in the prefrontal cortex was most prominent in a lateral band spanning primarily the prelimbic cortex. Although phencyclidine did not alter the uptake of (14)C-cystine in prefrontal cortical tissue punches, intraprefrontal cortical infusion of N-acetylcysteine (10-100 μM) significantly reduced phencyclidine- (1.5 mg/kg, sc) induced deficits in prepulse inhibition. N-Acetylcysteine was without effect when coinfused with CPG (0.5 μM), indicating an involvement of system xc(-).

CONCLUSIONS

These results indicate that phencyclidine disrupts sensorimotor gating through system xc(-) independent mechanisms, but that increasing cystine-glutamate exchange in the prefrontal cortex is sufficient to reduce behavioral deficits produced by phencyclidine.

Challenges in drug target discovery in bipolar disorder

INTRODUCTION

Misdiagnosis and subsequent inappropriate treatment of patients with bipolar disorder (BD) can worsen their clinical condition and outcome.

AREAS COVERED

This review focuses on the therapeutic targets which have been implicated in BD, including the glycogen synthase kinase 3 (GSK-3) and phosphoinositide signaling pathways. In addition, evidence is presented for potential new molecular strategies which involve targeting neuropeptide-converting endopeptidases, glutamatergic excitotoxicity, insulin signaling and dysfunctions in mitochondrial metabolism. Current limitations in study design, molecular platforms, preclinical and cellular models in the context of BD drug target discovery, suggest that there are many areas for improvement.

EXPERT OPINION

For the future outlook, this review outlines the importance of developments such as the use of BD patient-derived cellular models for providing better understanding of the BD etiology and robust translational drug screening tools in combination with developments in the fields of bioinformatics and systems biology.

The promise of N-acetylcysteine in neuropsychiatry

N-Acetylcysteine (NAC) targets a diverse array of factors germane to the pathophysiology of multiple neuropsychiatric disorders including glutamatergic transmission, the antioxidant glutathione, neurotrophins, apoptosis, mitochondrial function, and inflammatory pathways. This review summarises the areas where the mechanisms of action of NAC overlap with known pathophysiological elements, and offers a précis of current literature regarding the use of NAC in disorders including cocaine, cannabis, and smoking addictions, Alzheimer's and Parkinson's diseases, autism, compulsive and grooming disorders, schizophrenia, depression, and bipolar disorder. There are positive trials of NAC in all these disorders, and although many of these require replication and are methodologically preliminary, this makes it one of the most promising drug candidates in neuropsychiatric disorders. The efficacy pattern of NAC interestingly shows little respect for the current diagnostic systems. Its benign tolerability profile, its action on multiple operative pathways, and the emergence of positive trial data make it an important target to investigate.

Participant experiences from chronic administration of a multivitamin versus placebo on subjective health and wellbeing: a double-blind qualitative analysis of a randomised controlled trial

Background

While many randomised controlled trials have been conducted on multivitamins, to our knowledge no qualitative research exploring the subjective experience of taking a multivitamin during a clinical trial has been reported.

Methods

Semi-structured and open-ended written questions were incorporated into a 16-week double-blind, randomised, placebo-controlled, parallel groups trial of once-daily multivitamin administration. At the final study visit (week 16), three open-ended questions were posed to elucidate any positive, negative or unusual experiences from taking either the multivitamin or matched placebo. Qualitative thematic analysis was undertaken by researchers who were blind as to treatment condition of participants, and triangulation (independent analysis from three researchers) was employed to ensure methodological rigour. Participant’s experiences were categorised as “positive” or “negative” and a Chi Square analysis was then applied to each of the experiential themes, to compare experiences between the multivitamin and placebo groups, (subdividing the groups by gender). Usual experiences were categorised and discussed separately.

Results

Of the 182 participants enrolled, 116 completed the study and qualitative data were available from 114 participants. Thematic analysis revealed significant effects in favour of the multivitamin over placebo for participants experiencing increased energy levels (p=.022) and enhanced mood (p=.027). The beneficial effect on energy levels was particularly evident among female participants. A trend was found for participants reporting better sleep in the multivitamin over placebo. The multivitamin and placebo groups did not significantly differ in perceived positive or negative effects in areas relating to other aspects of mental function or physical health. No significant negative effects were revealed, although there was a non-significant trend for more people in the multivitamin group having minor digestive complaints.

Conclusion

This represents the first documented qualitative investigation of participants’ experience of chronic administration of a multivitamin. Results uncovered a range of subjective beneficial effects that are consistent with quantitative data from previously published randomised controlled trials examining the effects of multivitamins and B vitamin complexes on mood and well-being.

Trial registration

Prior to commencement this trial was registered with the Australian New Zealand Clinical Trials Registry ( http://www.anzctr.org.au) ACTRN12611000092998

N-acetylcysteine in psychiatry: current therapeutic evidence and potential mechanisms of action

There is an expanding field of research investigating the benefits of alternatives to current pharmacological therapies in psychiatry. N-acetylcysteine (NAC) is emerging as a useful agent in the treatment of psychiatric disorders. Like many therapies, the clinical origins of NAC are far removed from its current use in psychiatry. Whereas the mechanisms of NAC are only beginning to be understood, it is likely that NAC is exerting benefits beyond being a precursor to the antioxidant, glutathione, modulating glutamatergic, neurotropic and inflammatory pathways. This review outlines the current literature regarding the use of NAC in disorders including addiction, compulsive and grooming disorders, schizophrenia and bipolar disorder. N-acetylcysteine has shown promising results in populations with these disorders, including those in whom treatment efficacy has previously been limited. The therapeutic potential of this acetylated amino acid is beginning to emerge in the field of psychiatric research.