Aggression in correctional and psychiatric settings is relatively common and has a negative effect on physical and mental health both among inmates/clients and staff, as well as organizational‐level functioning. The aim of the present study was to critically review the evidence on the effectiveness of nutritional supplements in reducing aggression and violence to contribute to a better understanding of options available for managing aggressive behaviors in adults. The EMBASE, MEDLINE, PsycINFO, Cochrane Library, and PubMed databases were searched for effectiveness studies published in English anytime up until March 2020. Study quality was assessed using the Mixed Methods Appraisal Tool. Altogether, 14 studies met inclusion criteria; 2 investigated micronutrients, 10 examined macronutrients, while further 2 examined a combination of micro and macronutrients. Out of the 14 studies, 5 reported a beneficial effect of nutritional supplementation (omega‐3 fatty acids, vitamins/minerals, S‐adenosyl‐l‐methionine, or tryptophan). Five studies did not report a significant beneficial effect of nutritional supplementation (omega‐3 fatty acids, folic acid, tryptophan, broad range supplement containing vitamins and fatty acids, and fatty acids in augmentation with valproic acid), while four studies reported mixed effects (on l‐tryptophan, broad‐range micronutrient formula, folic acid, and omega‐3 fatty acids). The results overall indicated that research in this area is in its infancy: very few studies examined the same composition of nutritional supplementation and when they did so the results were contradictory. The methodological shortcoming of existing studies and directions for future research are discussed to facilitate high‐quality research in this evolving area of nutritional psychiatry.
Practice is required to improve one’s shooting technique in basketball or to play a musical instrument well. Learning these motor skills may be further enhanced by transcranial direct current stimulation (tDCS). We aimed to investigate whether tDCS leads to faster attainment of a motor skill, and to confirm prior work showing it improves skill acquisition and retention performance. Fifty-two participants were tested; half received tDCS with the anode on primary motor cortex and cathode on the contralateral forehead while concurrently practicing a sequential visuomotor isometric pinch force task on Day 1, while the other half received sham tDCS during practice. On Day 2, retention of the skill was tested. Results from a Kaplan-Meier survival analysis showed that participants in the anodal group attained a pre-defined target level of skill faster than participants in the sham group (χ2 = 9.117, p = 0.003). Results from a nonparametric rank-based regression analysis showed that the rate of improvement was greater in the anodal versus sham group during skill acquisition (F(1,249) = 5.90, p = 0.016), but there was no main effect of group or time. There was no main effect of group or time, or group by time interaction when comparing performance at the end of acquisition to retention. These findings suggest anodal tDCS improves performance more quickly during skill acquisition but does not have additional benefits on motor learning after a period of rest.
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