Maintenance N-acetyl cysteine treatment for bipolar disorder : a double-blind randomised placebo controlled trial

Background N-acetyl cysteine (NAC) is a glutathione precursor that has been shown to have antidepressant efficacy in a placebo-controlled trial. The current study aimed to investigate the maintenance effects of NAC following eight weeks of open-label treatment for bipolar disorder.

Method The efficacy of a double blind randomized placebo controlled trial of 2 g/day NAC as adjunct maintenance treatment for bipolar disorder was examined. Participants (n = 149) had a Montgomery Asberg Depression Rating Score of [greater than or equal to]12 at trial entry and, after eight weeks of open-label NAC treatment, were randomized to adjunctive NAC or placebo, in addition to treatment as usual. Participants (primarily outpatients) were recruited through public and private services and through newspaper advertisements. Time to intervention for a mood episode was the primary endpoint of the study, and changes in mood symptoms, functionality and quality of life measures were secondary outcomes.

Results There was a substantial decrease in symptoms during the eight-week open-label NAC treatment phase. During the subsequent double-blind phase, there was minimal further change in outcome measures with scores remaining low. Consequently, from this low plateau, between-group differences did not emerge on recurrence, clinical functioning or quality of life measures.

Conclusions There were no significant between-group differences in recurrence or symptomatic outcomes during the maintenance phase of the trial; however, these findings may be confounded by limitations. Trial Registration The trial was registered with the Australian New Zealand Clinical Trials Registry (ACTRN12607000074493).

Effects of N-acetyl cysteine on cognitive function in bipolar disorder

Aims

Bipolar disorder is characterized by progressive changes in cognition with declines in executive functioning, memory and sustained attention. Current pharmacotherapies for bipolar disorder target mood symptoms but have not addressed these cognitive changes resulting in euthymic individuals who still experience cognitive deficits. N-acetyl cysteine (NAC) has been shown to have effects on antioxidant status, glutamate transmission, inflammation and neurogenesis. Adjunctive treatment with NAC improves the symptoms experienced by those with bipolar disorder, particularly depression, and it was hypothesized that cognition may also be improved following NAC treatment.
Methods

As part of a larger randomized, double-blind, placebo-controlled trial, participants in the current report were tested at baseline and 6 months to assess changes in cognitive function following either 2000 mg of NAC daily or placebo.
Results

This study failed to find changes in cognitive function following treatment with NAC compared to placebo.
Conclusions

While an important pilot study, this study had a small sample size and included a limited battery of cognitive tests. Further investigations on the effects of NAC on cognitive performance in bipolar disorder are required.

Metabolite profiles in the anterior cingulate cortex of depressed patients differentiate those taking N-acetyl-cysteine versus placebo

Background: Increased oxidative stress is thought to contribute to the pathophysiology of major depressive disorder (MDD), which is in part due to diminished levels of glutathione, the primary anti-oxidant of the brain. Oral administration of N-acetyl-cysteine (NAC) replenishes glutathione and has therefore been shown to reduce depressive symptoms. Proton magnetic spectroscopy (1H-MRS) that allows quantification of brain metabolites pertinent to both MDD and oxidative biology may provide some novel insights into the neurobiological effects of NAC, and in particular metabolite concentrations within the anterior cingulate cortex (ACC) are likely to be important given the key role of this region in the regulation of affect.

Objective: The aim of this study was to determine whether the metabolite profile of the ACC in MDD patients predicts treatment with adjunctive NAC versus placebo.

Methods: This study was nested within a multicentre, randomized, double-blind, placebo-controlled study of MDD participants treated with adjunctive NAC. Participants (n = 76) from one site completed the spectroscopy component at the end of treatment (12 weeks). Spectra from a single-voxel in the ACC were acquired and absolute concentrations of glutamate (Glu), glutamate-glutamine (Glx), N-acetyl-aspartate (NAA) and myo-inositol (mI) were obtained. Binary logistic regression analysis was performed to determine whether metabolite profiles could predict NAC versus placebo group membership.

Results: When predicting group outcome (NAC or placebo), Glx, NAA and mI were a significant model, and had 75% accuracy, while controlling for depression severity and sex. However, the Glu, NAA and mI profile was only predictive at a trend level, with 68.3% accuracy. For both models, the log of the odds of a participant being in the NAC group was positively related to NAA, Glx and Glu levels and negatively related to mI levels.

Conclusion: The finding of higher Glx and NAA levels being predictive of the NAC group provides preliminary support for the putative anti-oxidative role of NAC in MDD.

A preliminary investigation on the efficacy of N-acetyl cysteine for mania or hypomania

Objective: Oxidative imbalance has emerged as a treatment target in bipolar disorder. As very limited data are available on the clinical use of antioxidants for mania, we report here results from a post hoc and exploratory subgroup analysis of a randomized, placebo-controlled trial of N-acetyl cysteine (NAC).

Methods: This was a placebo-controlled, randomized, clinical trial assessing the effect of NAC over 24 weeks in mania or hypomania. Symptomatic and functional outcomes were collected over the study period.

Results: Fifteen participants were available for this report; two participants in each group failed to complete all assessments. Within-group analyses pointed to an improvement in the NAC group on manic symptoms and worsening in the placebo group on depressive symptoms at endpoint.

Conclusions: Although the sample size was small, these results indicated within-group efficacy for this glutathione precursor as compared to placebo. Future trials specifically designed to demonstrate the efficacy of NAC in mania are needed.

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 randomized in a double fashion to 24weeks (placebo=62; NAC=59). Clinical and functional variables were collected over the treatment period. Duration of the illness at baseline was grouped into <10years, 10-<20years and >20years. 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 effects related outcomes. The pattern of changes suggests this mediator effect of duration of illness in response to treatment is more evident in those participants with 20years 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.

Genetic polymorphisms in glutathione-S-transferases are associated with anxiety and mood disorders in nicotine dependence

Nicotine dependence is associated with an increased risk of mood and anxiety disorders and suicide. The primary hypothesis of this study was to identify whether the polymorphisms of two glutathione-S-transferase enzymes (GSTM1 and GSTT1 genes) predict an increased risk of mood and anxiety disorders in smokers with nicotine dependence.