Autism, or childhood autism, is a subtype of pervasive developmental disorder that is prevalent in males and begins in infancy and early childhood, manifested mainly by varying degrees of speech and language developmental disorders, interpersonal difficulties, narrow interests and stereotyped behavior. About 3/4 of patients have significant mental retardation, and some children have good abilities in one area against a background of general intellectual backwardness. The etiology of autism may be related to the following factors: 1. Genetics The role of genetic factors in autism has become clear, but the specific mode of inheritance is unknown. 2. Perinatal factors Various complications during the perinatal period, such as birth injuries and intrauterine asphyxia, are more frequent than in normal controls. 3.Immune system abnormalities Decreased number of T lymphocytes, decreased number of helper T cells and B cells, lack of suppressor-induced T cells, and reduced activity of natural killer cells were found. 4. Neuroendocrine and neurotransmitter Related to a variety of neuroendocrine and neurotransmitter dysfunctions. Studies have found that monoamine systems, such as 5-hydroxytryptamine (5-HT) and catecholamines, are immature in autistic patients, and that the pineal-subthalamic-pituitary-adrenal axis is abnormal, leading to increased 5-HT and endorphins and decreased secretion of adrenocorticotropic hormone (ACTH). Clinical manifestations 1. Language and communication disorders Language and communication disorders are important symptoms of autism and are the main reason for most children to be seen. Most children with autism have delayed or impaired language development, usually still not speaking at the age of two and three, or regression in language after normal language development, expressive language until the age of two to three, gradually decreasing with age or even completely lost, lifelong silence or limited use of language in rare cases. They have some degree of impairment in the perception of language and the ability to use it expressively. Patients with social interaction disorders cannot establish normal interpersonal relationships with others. At a young age, they show no eye contact with others, have poor expressions, lack expressions or gestures expecting hugs and caresses from parents and others, and do not have pleasant expressions when enjoying caresses, and even refuse hugs and caresses from parents and others. They do not distinguish between close and distant relationships and treat their relatives the same way as they treat others. For example, they are often alone in kindergarten and do not like to play with their peers; when they see some children playing games together, they do not have the interest to watch or the desire to participate. 3. Narrow range of interests and stereotypical behavior patterns Patients are not interested in the games and toys that normal children are interested in, but prefer to play with non-toy objects, such as a bottle cap or observing a spinning fan, and can last for tens of minutes or even hours without feeling bored. The patient is not interested in the main features of the toy, but is very concerned with the non-main features: the patient stubbornly demands that the routine remain the same, e.g., the time of going to bed, the quilt covered, and the same route to take when going out. If these activities are stopped or the behavior pattern is changed, the patient expresses significant unpleasantness and anxiety, and even defiant behavior. Patients may have repetitive stereotyped actions, such as repeatedly clapping their hands, spinning around, licking the wall with their tongue, stamping their feet, etc. 4. Intellectual disability Among autistic children, the level of intellectual performance is very inconsistent, with a few patients in the normal range and most patients showing varying degrees of intellectual disability. Domestic and international studies have shown that about 50% of autistic children are found to have more than moderate intelligence deficiency (IQ less than 50), 25% have mild intelligence deficiency (IQ 50-69), 25% have normal intelligence (IQ greater than 70), and those with normal intelligence are called high-functioning autism. Disease diagnosis By taking a comprehensive and detailed growth and development history, medical history and psychiatric examination, if typical clinical manifestations such as impaired speech development and social interaction, narrow range of interests and stereotypical repetitive behavioral patterns are found to gradually appear before the age of 3 years, and other widespread disorders such as childhood schizophrenia, mental retardation, Asperger syndrome, Heller syndrome and Rett syndrome are excluded, a diagnosis of childhood autism can be made. The diagnosis of childhood autism can be made by excluding other pervasive developmental disorders such as schizophrenia, mental retardation, Asperger syndrome, Heller syndrome and Rett syndrome. A small number of patients have an atypical clinical presentation that only partially meets the criteria for autism symptoms or have an atypical age of onset, for example, symptoms appear after the age of 3 years. These patients can be diagnosed as atypical autism. Such patients should continue to be observed and followed up to eventually make a correct diagnosis. Treatment of the disease 1. Training intervention methods Although there are many intervention methods for autism, most of them lack evidence-based medical evidence. There is no optimal treatment plan, and the best treatment method should be individualized. Among them, education and training are the most effective and primary treatment methods. The goal is to promote language development, improve social interaction, and acquire basic life skills and learning skills. Patients with autism usually receive education and training at home, special education schools, and medical institutions before school age because they cannot adapt to ordinary kindergarten life. After school age, their language and social skills will improve, and some of them can be educated in ordinary elementary schools together with children of the same age, while others may remain in special education schools. However, medication can improve some emotional and behavioral symptoms of patients, such as emotional instability, attention deficit and hyperactivity, impulsive behavior, aggressive behavior, self-injurious and suicidal behavior, tic and compulsive symptoms, and psychotic symptoms, which are helpful to maintain patients’ own or others’ safety and smoothly implement education Training and psychotherapy. Commonly used medications are as follows: (1) Central excitatory medications For people with combined attention deficit and hyperactivity symptoms. The most commonly used drug is methylphenidate. (2) Anti-psychotic drugs should be used in small doses for a short period of time, and attention should be paid to side effects, especially extrapyramidal side effects. ②Haloperidol: effective for behavioral symptoms such as impulsivity, hyperactivity and stereotypy and affective symptoms such as emotional instability and irritability as well as psychotic symptoms, and reported to improve social interaction and language developmental disorders. (3) Aripiprazole, quetiapine, olanzapine and other atypical antipsychotics: also effective in controlling impulsivity, aggression and psychotic symptoms of patients. (3) Antidepressants Can reduce repetitive stereotypic behaviors, obsessive-compulsive symptoms, improve mood problems, and enhance social interaction skills. They are also effective for motor disorders such as withdrawal, delayed dyskinesia, and tics that occur after the use of dopamine receptor blockers. Selective 5-HT reuptake inhibitors (SSRIs) are effective for behavioral and emotional problems in patients with autism. For example, sertraline can be tried in patients over 6 years of age.