Effect of Sodium Benzoate vs Placebo Among Individuals With Early Psychosis: A Randomized Clinical Trial.

Importance: There is evidence that sodium benzoate (BZ) may be an effective adjunctive treatment for schizophrenia. The clinical efficacy of BZ has been investigated in chronic schizophrenia; however, the efficacy of this agent has not been studied in individuals with early psychosis. Objective: To examine the clinical efficacy of the adjunctive use of BZ for symptoms in people with early psychosis. Design, Setting, and Participants: Using a placebo-controlled double-masked parallel-group design, this randomized clinical trial was conducted from August 2015 to July 2018. Participants aged between 15 and 45 years experiencing early psychosis were enrolled from 5 major clinical sites in Queensland, Australia. Data analysis was conducted from October 2018 to February 2020. Interventions: Participants were randomized 1:1 (50 participants in each group) to receive 500 mg of sodium benzoate twice daily or placebo for 12 weeks. Main Outcomes and Measures: The primary efficacy outcome was the Positive and Negative Syndrome Scale (PANSS) total score at 12 weeks. The key secondary efficacy measures were (1) the Clinical Global Impression score, (2) the Hamilton Depression Rating Scale for depression, (3) functioning as assessed by the clinician-rated Global Assessment of Function, and (4) the Assessment of Quality of Life Scale. The PANSS subscale scores and impact on selected amino acid concentrations were also assessed. Results: The study comprised 100 participants with a mean (SD) age of 21.4 (4.1) years, of whom 73 (73%) were male individuals. The mean (SD) baseline PANSS score was 75.3 (15.4). We found no improvement in total PANSS score in the BZ group compared with the placebo group. The end result of least-squares mean difference (SE) for total PANSS was -1.2 (2.4) (P = .63). There were no differences in any subscales of the PANSS, any secondary measures, nor any amino acid concentrations. The dose of BZ was well tolerated without any clinically significant treatment-emergent adverse event differences between BZ and placebo groups. Conclusions and Relevance: In this randomized clinical trial, there was no evidence that adjunctive use of 500 mg of BZ twice daily is an effective treatment for individuals with early psychosis. Trial Registration: anzctr.org.au Identifier: ACTRN12615000187549.

Is there a role for antibodies targeting muscarinic acetylcholine receptors in the pathogenesis of schizophrenia?

OBJECTIVE: Muscarinic receptor dysfunction has been suggested to play an important role in the pathophysiology of schizophrenia. Recently, it has also become clear that immune reactivity directed against neurotransmitter receptors may play a pathogenic role in some cases of schizophrenia. The aim of this review is to summarize the case for muscarinic receptor dysfunction in schizophrenia and the evidence supporting the hypothesis that this dysfunction is related to the development of muscarinic receptor-targeting antibodies. METHOD: The article reviews studies of muscarinic receptors and the presence and potential role(s) of anti-muscarinic acetylcholine receptor antibodies in people with schizophrenia. RESULTS: There is accumulating evidence that altered or deficient muscarinic signalling underlies some of the key clinical features of schizophrenia. Although the number of studies investigating anti-muscarinic acetylcholine receptor antibodies in schizophrenia is relatively small, they consistently demonstrate that such antibodies are present in a proportion of patients. This evidence suggests that these antibodies could have pathogenic effects or exist as a biomarker to an unknown pathophysiological process in schizophrenia. CONCLUSION: The presence of elevated levels of anti-muscarinic acetylcholine receptor antibodies may identify a subgroup of people with schizophrenia, potentially informing aetiopathogenesis, clinical presentation and treatment. To date, all studies have examined antibodies in participants with chronic schizophrenia, who have likely received antipsychotic medication for many years. As these medications modulate immune functions and regulate receptor densities, it is recommended that future studies screen for the presence of anti-muscarinic antibodies in people experiencing their first episode of psychosis.

Cognitive outcomes following anti-N-methyl-D-aspartate receptor encephalitis: A systematic review.

INTRODUCTION: Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an immune-mediated neurological disorder that (among other severe neuropsychiatric symptoms) affects cognition. This study aimed to summarize current knowledge regarding the rates, nature, and predictors of neuropsychological dysfunction in patients recovering from anti-NMDAR encephalitis. METHOD: A systematic review of studies describing neuropsychological outcomes following anti-NMDAR encephalitis was conducted. Electronic databases Medline, PsycINFO, EMBASE, and CINAHL were searched from inception to September 2016. Results were summarized using descriptive statistics and a series of chi-square analyses. RESULTS: Of 4030 identified studies, 44 were included. These reported neuropsychological outcomes for 109 treated patients (83.5% female, Mage = 22.5 years, range = 2-67) recovering from anti-NMDAR encephalitis. High rates of neuropsychological dysfunction were identified, with diverse impairments of variable severity documented in >75% of patients at assessments conducted during acute, subacute, and longer term recovery periods. Despite this, cognitive outcomes were ultimately considered favorable in most cases (74.3%). This estimate does not account for the potential impact of relapses. The frequency of impairments in overall intellectual functioning, language, attention, working memory, and visuospatial functions were significantly higher within the acute recovery period than in later phases of convalescence. However, rates of impaired processing speed, episodic memory, and aspects of executive functioning were consistent across time points. Adverse neuropsychological outcomes occurred at significantly higher frequency in patients where immunotherapy was delayed, χ2(1, N = 66) = 10.84, p < .003. CONCLUSIONS: Neuropsychological deficits are prevalent at all points of recovery from anti-NMDAR encephalitis, although improvement in cognitive outcomes can be expected as patients recover. Some cognitive deficits may be less likely than others to resolve. Close neuropsychological monitoring is warranted in this population. Longitudinal studies of neuropsychological functioning of patients with anti-NMDAR encephalitis are needed to accurately inform prognosis.

Cognitive and Social Functioning Deficits after Anti-N-Methyl-D-Aspartate Receptor Encephalitis: An Exploratory Case Series.

BACKGROUND: Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a recently described life-threatening autoimmune disorder associated with a characteristic multi-stage neuropsychiatric syndrome. Although it is known that the majority of patients experience neuropsychological disturbance post-treatment, some aspects of the cognitive profile remain unclear. METHODS: This study sought to investigate patterns of cognitive functioning in a sample of anti-NMDAR encephalitis patients. Seven (6F:1M; mean age, 26.4 years; range, 16-37 years) treated patients completed a comprehensive set of neurocognitive and social functioning measures. Performance was analyzed using normative data (where available), and comparison with matched controls (10F:4M; mean age, 25.8 years; range, 16-38 years). RESULTS: Individual cognitive profiles ranged from within normal limits to extensive dysfunction. Relative to controls, the patient group's performance was affected in the domains of verbal/ visual memory, working memory, attention, processing speed, executive functioning, and social cognition. The patient group also reported significantly higher levels of anxiety compared to controls. CONCLUSIONS: These results add to the accumulating evidence that neurocognitive deficits, consistent with the distribution and functions of the NMDAR system can persist during recovery from anti-NMDAR encephalitis. This is the first study to provide evidence of performance decrements on measures of social cognition, including some involving theory of mind. (JINS, 2016, 22, 828-838).

Visual spatial attention has opposite effects on bidirectional plasticity in the human motor cortex.

Long-term potentiation (LTP) and long-term depression (LTD) are key mechanisms of synaptic plasticity that are thought to act in concert to shape neural connections. Here we investigated the influence of visual spatial attention on LTP-like and LTD-like plasticity in the human motor cortex. Plasticity was induced using paired associative stimulation (PAS), which involves repeated pairing of peripheral nerve stimulation and transcranial magnetic stimulation to alter functional responses in the thumb area of the primary motor cortex. PAS-induced changes in cortical excitability were assessed using motor-evoked potentials. During plasticity induction, participants directed their attention to one of two visual stimulus streams located adjacent to each hand. When participants attended to visual stimuli located near the left thumb, which was targeted by PAS, LTP-like increases in excitability were significantly enhanced, and LTD-like decreases in excitability reduced, relative to when they attended instead to stimuli located near the right thumb. These differential effects on (bidirectional) LTP-like and LTD-like plasticity suggest that voluntary visual attention can exert an important influence on the functional organization of the motor cortex. Specifically, attention acts to both enhance the strengthening and suppress the weakening of neural connections representing events that fall within the focus of attention.