The disease usually starts within 30-36 months of age. In most children, early symptoms appear in infancy and are apparent by 12-30 months of age. In a small number of children, symptoms are minimal or completely normal in the first 12 months of life, and then become apparent between 12 and 30 months of age, with deterioration of language function, disappearance of a few words that were already expressed, and typical autism symptoms. Usually, however, it is difficult to determine when the disease starts in a sick child due to the parents’ lack of knowledge about the infant’s psychological and behavioral developmental procedures and the usual lack of close observation. Clinical symptoms: Autism is characterized by a lack of interest in social interaction, verbal communication and play powder, stereotyped repetitive stereotyped movements, and a compulsion to maintain a life environment and lifestyle. Most children with autism show a lack of interest in people during infancy and early childhood, and when their mothers hold them for breastfeeding, they do not get close to their mothers, they do not look at their mothers and smile, and they usually do not watch their parents’ movements. Some children have normal or basically normal development even at the age of 1~2 years, but after the onset of the disease, they show hunger. When in pain or discomfort, they do not run to their parents for food comfort, or just pull their parents’ hands to fetch something without expressing it with words or postures. These children are often indifferent to their parents leaving or returning, and will interact with them even when they are standing around, much less look at them, appearing extremely lonely. Children with autism also lack mutual social interactions and do not interact with children around them, much less establish friendships. (1) Children with autism often cry or scream to express their discomfort or needs: older children may take the hand of an adult and walk towards something they want. Lacking appropriate facial expressions, they often appear indifferent and rarely nod, shake their heads, pose, etc. to express their will. (2) Delayed or no language development: Children with the disease often show later language development than their peers, and some even do not develop. Some children also have a gradual decrease or even complete loss of language function after it appears before the age of 2 to 3 years. (3) Abnormalities in the content and form of language: Even if they exist, autistic children have many problems. Children with autism often do not initiate conversations with others, do not maintain or ask questions, or only dwell on the same topic repeatedly, without caring about the reactions of others. They often speak “to” people rather than “with” them, and verbal communication is difficult. Stereotyped repetitive language and imitative language are also common, as the child will often only repeat what you say when talking to him. Some may imitate what is said on TV, radio, or by others at the time or at a later time. Some children may talk to themselves or hum and enjoy themselves. In addition, children with autism may have abnormalities in voice, intonation, speech speed, speech rhythm and stress, and may speak in a strange or flat voice without emotion. Some children often misuse personal pronouns, saying “I” instead of “you” or “I” instead of “he”. etc. 3. Narrow interest: adherence to the same format and ritualistic strong sexual behavior. (1) Narrow interests and unusual attachment behaviors: Children with autism lack interest in toys and games that children generally like, especially in imaginative games, but are particularly interested in objects that are not usually used as toys, such as wheels, bottle caps, and other round, spinable objects. Some sick children also develop attachment behaviors to plastic bags, door locks, certain fruits, etc. For example, a 3-year-old female child was holding a large red brick weighing 2.5 kg and refused to let go of it even when she was sleeping. It is rare for this child to develop attachment to living things. They are often interested in the non-primary characteristics of objects. For example, they like to touch the smooth ground repeatedly. (2) Unwillingness to change daily habits: Children with autism are often stubborn about their environment and become anxious when changes occur. This is also true for daily living habits. For example, some children only eat fixed food, and some require to sit in a fixed position when eating. Some also like to arrange toys or objects in rows and appear distressed or throw a tantrum if they are messed up. Almost all children with autism refuse to learn or engage in new activities. (3) Ritualistic or compulsive behaviors: e.g. twisting or flicking fingers in front of them, clapping hands. Some children spend a lot of time dwelling on memorizing weather forecasts, the capitals of some countries, and the birthdays of family members. Older children often ask the same questions repeatedly and touch or smell objects uncontrollably. Such ritualistic or compulsive behaviors are more common in children with normal intelligence. Sensory and motor disorders: The child is numb to pain and external stimuli. For example, a sudden sound may cause a jump in a normal child, but the child with autism does not. Many parents suspect that their child is “deaf” and seek medical attention for the first time. When a person stands in front of the child, the child does not seem to see him or her, or he or she only looks at one of the hands or a part of the child. The child often rubs, taps, bumps his head, bites hard objects, shakes or rotates his body to elicit his senses. Children are particularly sensitive to certain stimuli, especially to the sound of sirens, vacuum cleaners, barking dogs and sudden changes in light, which often cause panic or irritability. Some children do not cry out in pain when their fingers are injured, but cannot tolerate the itchiness of separate arrangements. Sensory numbness and allergy can coexist in one child. Children with autism are unable to sit still and are constantly moving. The child often walks or runs or runs instead of walking, looks around, and has darting eyes that make it difficult to concentrate for long periods of time. They often stretch their necks and make strange postures, and some of them even laugh or cry inexplicably. 5. Intelligent and cognitive impairment: About 50% of autistic children have moderately and severely depressed intellectual ability (IQ below 49), about 25% have mildly depressed level (IQ 50~70), and 25% can remain normal. Children with mild or normal IQ levels may be considered to be eccentric and not be seen in the hospital as pathological. Whether the child has a low or high IQ, the main symptoms of presentation are similar, except that children with a low IQ have more severe levels of social interaction and social reactions, stereotypic and self-injurious behaviors, and more frequent seizures. In their 1967 study of IQ in autistic children, Rutter and Lackyer found that autistic children were superior on tests of applied manipulation, visual-spatial skills, and immediate tests, and inferior on those of symbolic, abstract thinking, and logical procedures. Other cognitive deficits were found in imitation, comprehension of oral words and gestures, and dexterity. The deficits in rule making and application were much more extensive and severe compared to non-autistic children with the same IQ. In addition, cognitive deficits are more extensive in children with autism with low intelligence compared to children with normal intelligence. Some children with autism have “solitary aptitudes” in addition to low IQ, and are known as “idiot geniuses” because of their special abilities in music, date calculation, mechanical memory, and memorization. Children with autism may have a sense of inappropriateness or disproportionality to the situation. They often cry for no reason, cry loudly, and have difficulty calming down through reassurance. There is also unexplained giggling. There is no fear of things that children are generally afraid of, such as cars, tall buildings and furred animals. Children often spin around without getting dizzy and self-injurious behavior is common. Seizures can occur in early childhood or adolescence, with the latter being more common. Course and prognosis: Children with autism, like other children, change as they develop. Typical cases are common in the preschool years. By school age, many children with autism develop a limited attachment to their parents and respond socially to different situations. Verbal communication skills may also be somewhat developed, but are significantly deviated. Self-injurious behavior and other behavioral problems are more common and become more difficult to manage. At least through the years, a minority of children with autism show improvement in symptoms, while others show behavioral decline. Those with severe mental retardation may experience seizures into adulthood, and many autistic patients are in a state of severe functional deficit. The severity of autism can be classified as low-functioning or high-functioning. Most high-functioning children develop normally or basically normally in the first 1-2 years, maintain simple cognitive and verbal communication functions, maintain some emotional contact with parents and others around them, have no seizures and no obvious organic brain signs, and later develop less severe behavioral features of autism; the opposite is true for low-functioning children. Those children with high functioning disorders may achieve some academic and vocational success.