Childhood autism is a subtype of pervasive developmental disorder that is more common in males and begins in infancy and early childhood. It is characterized by varying degrees of speech and language development, interpersonal difficulties, narrow interests and stereotyped behavior. So, what are the causes of autism in children? The following are the causes of autism in children: 1. Perinatal factors The role of genetic factors in autism has been confirmed, but the specific mode of inheritance is not known. Neuroendocrine and neurotransmitter dysfunction is associated with a variety of neuroendocrine and neurotransmitter dysfunctions. It has been found that the monoamine system, such as 5-hydroxytryptamine (5-HT) and catecholamines, is immature in autism, and that the pineal-subthalamic-pituitary-adrenal axis is abnormal, leading to an increase in 5-HT and endorphins and a decrease in the secretion of adrenocorticotropic hormone (ACTH). 3. Abnormalities in the immune system are found, such as a decrease in the number of T lymphocytes, the number of helper T cells and B cells system-induced T cell deficiency, and reduced natural killer cell activity.