This is a double-blind randomized controlled trial. During a period of 2.5 months, 74 ADHD children recruited from Clinic of Noor and Ali Asghar of Isfahan University of Medical Sciences. The study was approved by Ethics Committee of Isfahan University of Medical Sciences, Isfahan, Iran. This trial was registered at Iranian Registry of Clinical Trials as IRCT2016030326886N1.
The inclusion criteria included; 1) Diagnosis of ADHD based on the presence of at least 6 out of 9 cases of inattention and also at least 6 out of 9 cases of hyperactivity based on DSM IV (Diagnostic and Statistical Manual of Mental Disorders, fourth edition), 2) Ages between 6–12 years, 3) Serum level of 25-hydroxyvitamin D₃ less than 30 ng/dL (21), 4) Serum magnesium levels are less than 2.3 mg/dL (22), 5) Consent to participate in the study. Exclusion criteria included; 1) Suffering from chronic medical or other psychiatric disorders, 2) Taking any multivitamin/mineral before initiating or during study.
In order to observe the ethical considerations, the method and the objectives of the research were explained to each participant and they entered the study with the written consent of their parents or legal guardian. Participants were divided into two groups of intervention and control by randomized double block method after stratification the sex. An independent person made random allocation cards using computer‑generated sequence and used sequentially numbered, sealed, opaque envelopes to conceal the allocation. Neither the researcher nor the participants were aware of the groups. Intervention group received pearl of Vitamin D (50,000 IU/week) and oral tablet of magnesium (6 mg/kg/day) (23). Control group received placebo which were similar in appearance, color, and taste to these supplements. Duration of intervention was 8 weeks. Participant’s compliance was measured through compare the serum levels of Vitamin D and magnesium before and after the intervention in two groups (24).
Baseline characteristics of participants were collected by questionnaire. Height and weight was measured with a precision of 0.5 cm and 100 g respectively. Body mass index (BMI) was calculated by weight in kilograms divided by height in meters squared. Serum levels of 25‑OH‑Vitamin D and magnesium were assessed at baseline and at the end of the intervention period. Serum levels of 25‑OH‑Vitamin D were measured by enzyme‑linked immunosorbent assay (ELISA) method with a commercially available ELISA kit from Immundiagnostik AG, Bensheim, Germany. Serum levels of magnesium were measured by an autoanalyzer (Hitachi 917, Roche Diagnostics® GmbH, Mannheim, Germany) using a commercially available kit.
Strength and difficulties questionnaire (SDQ) was used to evaluate mental health status of participants (25) at baseline and at the end of study (8th week). This scoring system contains 25 questions. Each of the five scale of the SDQ are scored from 0–10, and one can add up four of these (emotional, conduct, hyperactivity and peer problems) to create total difficulty score (range 0–40). One can also add the emotional and peer items together to get an internalizing problems score (range 0–20) and add the conduct and hyperactivity questions together to get an externalizing score (range 0–20).
Statistical analysis was performed using descriptive and inferential statistics
Kolmogorov–Smirnov test used to assess normality of variables distribution. To compare intragroup changes Wilcoxon signed‑rank test and Mann‑Whitney test was applied. Chi‑square test was used to assess the significance level of qualitative variables between the two groups. For all analyses, SPSS 19 (SPSS, Inc., Chicago, IL, USA) was used. P = 0.05 considered as significance level.