Constipation is occurs frequently in subjects with numerous chonic ailments including autism or autistic spectrum disorders and sometimes it’s just labelled as “functional”. Overall it is complex and an overall understanding including involvement of “big brain” (central nervous system), “our second brain” (enteric nervous system ) i.e. nervous system in gut) and brain-gut axis may explain why constipation is common among those suffering from autism/ASD.
Evidence suggests that there is increased prevalence of gastrointestinal symptoms (whether or organic or neurobehavioral) in autism. Based on gut-brain hypothesis, such symptoms could be the child’s method of communicating his/her symptoms to the care-giver.