Prenatal folic acid supplementation and autism spectrum disorder in 3-year-old offspring: the Japan environment and children's study

The role and impact of abnormal vitamin levels in autism spectrum disorders

The prevalence of autism spectrum disorder (ASD), a neurodevelopmental disorder with a predominance of social behavioral disorders, has increased dramatically in various countries in recent decades. The interplay between genetic and environmental factors is believed to underlie ASD pathogenesis. Recent analyses have shown that abnormal vitamin levels in early life are associated with an increased risk of autism. As essential substances for growth and development, vitamins have been shown to have significant benefits for the nervous and immune systems. However, it is unknown whether certain vitamin types influence the emergence or manifestation of ASD symptoms. Several studies have focused on vitamin levels in children with autism, and neurotypical children have provided different insights into the types of vitamins and their intake. Here, we review the mechanisms and significance of several vitamins (A, B, C, D, E, and K) that are closely associated with the development of ASD in order to prevent, mitigate, and treat ASD. Efforts have been made to discover and develop new indicators for nutritional assessment of children with ASD to play a greater role in the early detection of ASD and therapeutic remission after diagnosis.

The contribution of epidemiology to the understanding of neurodevelopmental disabilities

Epidemiological approaches have played an important role in creating better understanding of developmental disabilities by delineating their frequency in populations and changes in their frequency over time, by identifying etiological factors, and by documenting pathways to prevention. Both cerebral palsy (CP) and mild intellectual disability are declining in frequency in high-income countries. The diagnosis of autism spectrum disorder has increased in recent decades, but much of this increase is a result of changing approaches to ascertainment and recording. Epidemiological studies have found that most CP is not of birth-asphyxial origin, that most febrile seizures do not pose a major risk for epilepsy, and that folic acid deficiency may contribute to developmental disabilities apart from its effect on neural tube defects. Epidemiological research has shown that an important fraction of neural tube defects and virtually all cases of Reye syndrome are preventable, and recent trials have shown ways to prevent CP. Early psychoeducational interventions in children at risk for mild intellectual disability are an effective and valuable societal investment. Very large population-based studies starting in pregnancy have been launched in Norway, Denmark, and Japan in recent years and these and other population studies promise to continue the epidemiological contribution to a better understanding of developmental disabilities.