Academy of Medical Sciences of I.R. Iran Archives of Iranian Medicine 1029-2977 22 10 2019 10 01 Prevalence of Autism and its Comorbidities and the Relationship with Maternal Psychopathology: A National Population-Based Study 546 553 EN Mohammad Reza Mohammadi Nastaran Ahmadi Ali Khaleghi Hadi Zarafshan Seyed-Ali Mostafavi Koorosh Kamali Mehdi Rahgozar Ameneh Ahmadi Zahra Hooshyari Seyyed Salman Alavi Alia Shakiba Maryam Salmanian Parviz Molavi Nasrin Sarraf Seyed Kaveh Hojjat Soleiman Mohammadzadeh Shahrokh Amiri Soroor Arman Ahmad Ghanizadeh Journal Article 2018 12 30 2019 09 08 Background: There is no clear picture regarding the prevalence rates of autism and its comorbidities among Iranian children and adolescents. The present study aimed to estimate these rates as part of a large national population-based study on epidemiology of psychiatric disorders in Iranian children and adolescents. Methods: The total sample consisted of 31000 children and adolescents between 6 to 18 years of age. The Kiddie Schedule for Affective Disorders and Schizophrenia for School-Age Present and Life time version (K-SADS-PL) was used as the diagnostic tool. Results: The prevalence of autism in the total sample is equal to 0.1% (10 per 10000), with a 2:1 male-to-female ratio. In total, 86% of people with autism had at least one comorbid condition. Intellectual disability, epilepsy, enuresis and attention deficit and hyperactivity disorder (ADHD) with prevalence rates of 70.3%, 29.7%, 27% and 21.62%, respectively, were the most prevalent comorbid conditions in people with autism. Maternal personality disorders were also shown to be associated with increasing risk of autism. Conclusion: The present study shows high prevalence rates for autism and its comorbid conditions among Iranian children and adolescents. It also reveals that there is a relationship between some maternal psychiatric disorders and the risk of autism.