Objectives: Vitamin D deficiency may be linked to several mental complications including cognitive deficits, depression, and anxiety in patients under methadone maintenance treatment (MMT). This study was designed to explore the effect of vitamin D supplementation on cognitive functions and mental health parameters in subjects under MMT. Methods: This randomized, double-blinded, placebo-controlled clinical trial was carried out among 64 patients under MMT. Participants were randomly allocated to receive either 50,000 IU vitamin D supplements (n = 32) or placebo (n = 32) every 2 weeks for 24 weeks. Cognitive functions and mental health parameters were taken at baseline and posttreatment to evaluate relevant variables. Results: After the 24-week intervention, compared with the placebo, serum 25(OH) vitamin D levels significantly increased in participants who received vitamin D supplements (β 14.50; 95% confidence interval [CI], 13.17–15.83; P < 0.001). In addition, compared with the placebo, subjects who received vitamin D had a significant reduction in Iowa Gambling Task (β −6.25; 95% CI, −8.60 to −3.90; P < 0.001), and significant increases in Verbal Fluency Test (β 2.82; 95% CI, 0.78–4.86; P = 0.007), Immediate Logic Memory (β 1. 32; 95% CI, 0.27–2.37; P = 0.01), Reverse Digit Span (β 2.06; 95% CI, 1.18–2.94; P < 0.001) and visual working memory (β 0.75; 95% CI, 0.33–1.16; P = 0.001). Also, vitamin D supplementation significantly improved BDI (β −2.76; 95% CI, −3.97 to −1.55; P < 0.001) compared with the placebo. When we applied Bonferroni correction, LM-Immediate (P = 0.07) became nonsignificant, and other mental health parameters did not alter. Conclusions: Overall, taking 50,000 IU vitamin D supplements every 2 weeks for 24 weeks by patients under MMT had beneficial effects on cognitive functions and some mental health parameters. Further studies are needed to confirm our findings.

Background:The association of autism symptoms and cognitive abilities can facilitate the etiology and treatment of autism disorders. Destruction of executive functions is one of the several potential cognitive phenotypes in autism. Objectives: The purpose of this study was to investigate the relationship between deficit executive functions and behavioral symptoms in children with high-functioning autism. Materials and Methods:In this cross-sectional study, 50 children with high-functioning autism were selected using the convenience sampling method. The Gilliam autism rating scale, high-functioning autism spectrum screening questionnaire, The Stroop color and word test, continuous performance test and shifting attention test were administered. Pearson correlation coefficient and multi-variant regression were used to analyze the data. Results: There was a positive correlation between selective attention with communication and social interactions (P < 0.01, P < 0.05). There was a positive correlation between sustained attention with social interactions and stereotyped behaviors (P < 0.05, P < 0.001). Moreover, there also was a positive correlation between shifting attention and communication, social interactions and stereotyped behaviors (P < 0.05, P < 0.01, P < 0.001). The results of regression analysis showed that selective attention and shifting attention can predict communication (P < 0.01). Sustained attention can predict social interactions and stereotyped behaviors (P < 0.01, P < 0.05). Conclusions:The results of this study suggest that executive functions play an important role in symptoms of children with highfunctioning autism. It is recommended to design new therapeutic interventions to restore executive functions in children with highfunctioning autism.