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\u27s 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

Study on the L–H transition power threshold with RF heating and lithium-wall coating on EAST

The power threshold for low (L) to high (H) confinement mode transition achieved by radio-frequency (RF) heating and lithium-wall coating is investigated experimentally on EAST for two sets of walls: an all carbon wall (C) and molybdenum chamber and a carbon divertor (Mo/C). For both sets of walls, a minimum power threshold Pthr of ~0.6 MW was found when the EAST operates in a double null (DN) divertor configuration with intensive lithium-wall coating. When operating in upper single null (USN) or lower single null (LSN), the power threshold depends on the ion ∇B drift direction. The low density dependence of the L–H power threshold, namely an increase below a minimum density, was identified in the Mo/C wall for the first time. For the C wall only the single-step L–H transition with limited injection power is observed whereas also the so-called dithering L–H transition is observed in the Mo/C wall. The dithering behaves distinctively in a USN, DN and LSN configuration, suggesting the divertor pumping capability is an important ingredient in this transition since the internal cryopump is located underneath the lower divertor. Depending on the chosen divertor configuration, the power across the separatrix Ploss increases with neutral density near the lower X-point in EAST with the Mo/C wall, consistent with previous results in the C wall (Xu et al 2011 Nucl. Fusion 51 072001). These findings suggest that the edge neutral density, the ion ∇B drift as well as the divertor pumping capability play important roles in the L–H power threshold and transition behaviour

Physics and performance of the I-mode regime over an expanded operating space on Alcator C-Mod

New results on the I-mode regime of operation on the Alcator C-Mod tokamak are reported. This ELM-free regime features high energy confinement and a steep temperature pedestal, while particle confinement remains at L-mode levels, giving stationary density and avoiding impurity accumulation. I-mode has now been obtained over nearly all of the magnetic fields and currents possible in this high field tokamak (I-p 0.55-1.7 MA, B-T 2.8-8 T) using a configuration with B x del B drift away from the X-point. Results at 8 T confirm that the L-I power threshold varies only weakly with B-T, and that the power range for I-mode increases with B-T; no 8 T discharges transitioned to H-mode. Parameter dependences of energy confinement are investigated. Core transport simulations are giving insight into the observed turbulence reduction, profile stiffness and confinement improvement. Pedestal models explain the observed stability to ELMs, and can simulate the observed weakly coherent mode. Conditions for I-H transitions have complex dependences on density as well as power. I-modes have now been maintained in near-DN configurations, leading to improved divertor power flux sharing. Prospects for I-mode on future fusion devices such as ITER and ARC are encouraging. Further experiments on other tokamaks are needed to improve confidence in extrapolation.