Is high prevalence of Vitamin D deficiency evidence for autism disorder?: In a highly endogamous population

To determine the association between Vitamin D and autism, and the difference in level of Vitamin D in autism children and control.

Case-control study conducted between June 2011 and May 2013, among autism at the Hamad Medical Corporation and controls at the School Health Clinics and Primary Health Care Clinics.

A total of 254 cases and 254 controls. The Autism Diagnostic Observation Schedule-Generic is a semi-structured, standardized assessment of social interaction, communication, play and imaginative use of materials for individuals suspected of having autism spectrum disorders. Data on clinical manifestations and laboratory, family history, body mass index (BMI) and clinical biochemistry variables including serum 25-hydroxy Vitamin D, calcium, phosphorus and magnesium were obtained. Univariate and multivariate statistical analyzes were performed.

Of the total number of 508 children surveyed, 254 of autism and 254 of healthy children were contacted. The mean age (± standard deviation, in years) for autism versus control children was 5.51 ± 1.58 versus 5.76 ± 1.56. There were statistically significant differences between autism and healthy children control subjects with respect to educational level of mother (P = 0.016); occupation of mother (P = 0.005); BMI (P < 0.001); consanguinity (P = 0.015); exposure to sun (P = 0.002) and walking time per day <60 min (P < 0.001). The mean value of Vitamin D in autism children was much lower than the normal value, and there was a significant difference found in the mean values of Vitamin D between autism (18.39 ± 8.2 with median 18) and versus control children (21.59 ± 8.4) (P < 0.0001) and with median 21 (P = 0.004). Besides mean values of calcium, phosphorous, magnesium, glucose, potassium and alkaline phosphate were statistically significant higher in control healthy children compared to autism children (P < 0.001). Multivariate logistic regression analysis revealed that the mean serum Vitamin D level, calcium, consanguinity, BMI, physical activity, child order, and ferritin, were considered as the main factors associated with autism. Of total 254 of autism children, 14.2% had severe Vitamin D deficiency (<10 ng/ml), 43.7% had moderate insufficient levels (between 10 and 20 ng/ml), 28.3% had mild insufficient levels (between 20 and 30 ng/ml), and only 13.8% of autism had sufficient levels (>30 ng/ml). Similarly, of the total 254 of healthy children 8.3% had severe Vitamin D deficiency (<10 ng/ml), 37% had moderate insufficient levels (between 10 and 20 ng/ml), 37.4% had mild insufficient levels (between 20 and 30 ng/ml), and only 17.3% had sufficient levels (>30 ng/ml). Furthermore, there was statistically significant differences between autism and control subjects with respect to the serum level of Vitamin D (P = 0.023).

The present study revealed that Vitamin D deficiency was higher in autism children compared to healthy children and supplementing infants with Vitamin D might be a safe and more effective strategy for reducing the risk of autism.