Indian Journal of Biochemistry & Biophysics Vol. 55, December 2018, pp. 375-383 A Review Autism spectrum disorder (ASD): A current review of assessment, risk factors and prevention G Balaji & Sukesh Narayan Sinha* Food and Drug Toxicology Research Centre, National Institute of Nutrition, Indian Council of Medical Research, Jamai-Osmania, Hyderabad -500 007, India Received 29 January 2018; revised 04 July 2018 Autism spectrum disorders (ASDs) are extremely heritable neurodevelopmental disorders observed in 1-2% of children, usually seen before they reach 3 years of age. ASD is characterized by impaired social behavior, poor communication, stereotypic behavior, abnormal sensitivity to sensory stimuli and self-injurious behavior. The exact causes of ASD are unclear but increased oxidative stress; hyperserotonemia and loss of purkinje cell integrity in the cerebellum are some pathological findings in ASD. This article reviews trends in assessment of this neurodevelopmental disorder, autism risk factors, and preventions for autism. Screening tools for ASD, such as checklist for autism in toddlers (CHAT), modified checklist for autism in toddlers (M-CHAT), autism behavior checklist (ABC) and the autism spectrum screening questionnaire (ASSQ), social communication questionnaire (SCQ), australian scale for asperger syndrome (ASAS), are available for use by general pediatricians. Pregnant ladies exposure to some toxic chemicals and selective serotonin reuptake inhibitors (SSRIs) may increase the risk of ASDs. Mother and child cohort study (MoBa) found prenatal folic acid supplements reduce the risk of autism spectrum disorders in children, but these findings cannot determine whether they protect against other neurodevelopmental disorders. Keywords: Autism, Risk factors, Screening tools, Serotonin reuptake inhibitors Autism spectrum disorders (ASDs) are extremely heritable neurodevelopmental disorders observed in 1-2% of children with varying degree of symptoms and severity 1 . Autism was originally defined by Leo Kanner in 1943 as an innate inability to create normal, biologically determined, emotional contact with others 2 . Autism is usually seen in children before they reach 3 years of age. According to the first precise estimate of the country’s autism prevalence is approximately 23 in 10000 children in India. This comparison of, about 0.23 percent, is far less than 1.47% prevalent in the United States 3,4 (Fig. 1). Autism is characterized by impaired social behavior, poor communication, stereotypic behavior, abnormal sensitivity to sensory stimuli and self-injurious behavior 5 . The exact causes of ASD are unclear but increased oxidative stress 6,7 hyperserotonemia 8,9 and loss of Purkinje cell integrity in cerebellum 10 are some pathological findings in autism. Some children with ASD or ADHD (Attention-deficit/hyperactivity disorder) exhibit no obvious symptoms, making it difficult to reliably diagnose the disorders during childhood 11 . Brain alters in ASD include a reported 67% more neurons in the prefrontal cortex, more than 17% increase in brain weight and abnormal cortical patterning. Additional transcriptomic analysis of postmortem brains from human ASD individuals revealed altered expression of proteins which are important for functional synaptic activity in the prefrontal cortex and cerebellum 12 . Various factors like genetic aberrations, environmental offences, and social factors contribute to the development of autism. Chemicals like mercury, ethanol, thalidomide, and misoprostol produce a generation of reactive oxygen species (ROS) which are responsible for deficits in the development of the cerebellum, limbic system and of brain 5 . Several studies have reported on ASD-associated abnormalities in the peripheral nervous system, enteric nervous system, and neuroimmune system. ASD patients of Postmortem brains showed increase microglia and astroglia activation in the cerebellum and cerebral cortex, along with increased levels of proinflammatory cytokines in the cerebrospinal fluid and cortical regions _________ *Correspondence: Phone (Mob): +91-7032426802 E-mail: sukeshnr_sinha@yahoo.com (SNS), balajiroy4@gmail.com (GB)