Updated: Dec 1, 2022
By DiverseMinds Research Team
Reading time 5 minutes ⏰
Autism is divided into five types according to DSM 5: anxiety disorders, bipolar and related disorders, depressive disorders, feeding and eating disorders, obsessive-compulsive and related disorders, and personality disorders. Reports on the prevalence of autism vary, and it is generally believed to be about 1 in 44 children, with a male to female ratio of 3 to 4 to 1, and 3 to 4 times as many boys as girls.
The cause of Autism
Although the causes of autism are not fully understood, research suggests that certain risk factors may be involved. The risk factors of autism can be summarized as heredity, infection and immunity, and physical and chemical stimulation during pregnancy.
Twin studies have shown that the co-morbidity of autism is 61% to 90% in monozygotic twins, while there is no significant co-morbidity in dizygotic twins. Reprevalence among siblings is estimated at about 33%. These phenomena suggest a genetic predisposition to autism.
There are genetic polymorphisms in genes.
The numerous candidate genes suggest that autism is a polygenic genetic disease, that is, autism may be induced by environmental pathogenic factors under a certain genetic predisposition.
Infection and immune factors
Studies dating back to the late 1970s found that viral infections in pregnant women increased the risk of autism in their offspring. Several subsequent studies have suggested a possible link between infection during pregnancy and the development of autism. Known related pathogens include rubella virus, cytomegalovirus, varicella zoster virus, herpes simplex virus, treponema pallidum and Toxoplasma gondii. It is speculated that the antibodies produced by these pathogens enter the fetus from the placenta and have a cross-immune reaction with the developing nervous system of the fetus, which interferes with the normal development of the nervous system, thus leading to the occurrence of autism .
Stimulation of physical and chemical factors during pregnancy
A history of thalidomide and valproate antiepileptic drugs as well as alcoholism in pregnant women during early pregnancy can lead to an increased probability of autism in their offspring. According to these studies, a single high-dose intraperitoneal injection of sodium valproate in rats at 12.5 days of gestureshowed behavioral symptoms similar to autism in their offspring. Other studies have found that exposure to repeated cold stimulation in pregnant rats also increases the risk of autism in their offspring, who also exhibit behavioral characteristics of autism.