Mentalretardation, also known as mental retardation, is a syndrome of brain developmental disorders caused by a variety of reasons, mainly characterized by mental retardation and difficulties in social adaptation, and may be accompanied by certain mental or physical illnesses. The disease starts during the developmental period, and the intelligence improves slightly with age, but moderate and severe patients still bring a heavy burden to the family and society. Mild patients with no obvious abnormalities in physical development are often overlooked and selected in the recruitment experience, causing difficulties in training and management of the troops, which should be noted. This disease is more common, foreign reports the total prevalence of 8 per thousand (British) to 10 per thousand (U.S.), of which moderate and severe are 2 per thousand. The results of a joint survey of twelve regions in China in 1982: the prevalence of moderate and severe was 3.33 per thousand, and there is no data on the prevalence of mild patients. The prevalence rates reported outside are higher in rural than in urban areas, and higher in males than in females. Etiology, pathology, and pathogenesis The etiology is complex. Foreign data pointed out that: about 20% of mental retardation is caused by environmental factors, 25% by chromosomal abnormalities or genetic abnormalities, more than half of the patients can not find the cause of the disease. It is also found that 85% of severe patients can find biological causes, such as chromosomal abnormalities, congenital diseases, metabolic and endocrine abnormalities, infections, poisoning, trauma and other physical factors. The psychosocial factors causing mental retardation are difficult to analyze and summarize, and the more certain causes are summarized as follows: I. Genetic anomalies: mainly due to genetic or chromosomal abnormalities caused by neurological dysplasia, malformations or congenital metabolism Down syndrome, Turner syndrome; phenylketonuria, galactosemia, familial black haze dementia; neurofibromatosis, tuberous sclerosis, and congenital Hydrocephalus, brain penetrating malformation, microcephaly and so on. Second, fetal acquired abnormality: the first trimester of pregnancy is the stage of initial formation of fetal nervous system structure, which is easy to suffer from the damage of disease-causing factors and lead to obvious malformations. Maternal infections (viruses, spirochetes, toxoplasmosis), abdominal trauma or radiation exposure, psychoactive substance poisoning, endocrine diseases such as hypothyroidism, gestational toxemia, malnutrition, hypoxia and other serious diseases in the fetal period are one of the causes of mental retardation. Li Enyao, Department of Pediatric Rehabilitation Medicine, The Fifth Affiliated Hospital of Zhengzhou University (ZZU) Perinatal diseases: including preterm labor, obstructed labor, brain injury during delivery, neonatal asphyxia and kernel jaundice. Postnatal diseases: In the first 2 years after birth, brain development is the fastest, and brain damage caused by disease-causing factors in this period is also serious. Preschool age is the most critical period, followed by elementary school age. There are many causative factors, such as infection (especially central nervous system infection), craniocerebral trauma, poisoning, epilepsy, malnutrition, endocrine or metabolic diseases and post-vaccination encephalitis. In recent years, studies have shown that the stimulation of various sensory organs is an important factor in promoting the development and proliferation of brain nerve fibers. Social and environmental factors during the developmental period, especially the education in infancy and early childhood will affect the brain development. The study of wolf children and monkey children proves that the deprivation of cultural and educational opportunities in infancy and early childhood brings damage to the normal development of the brain, which cannot be remedied by any careful education in the future. Epidemiological surveys have found that low IQ is often associated with low socio-economic and cultural levels, overcrowded housing, and unstable family environments. Clinical manifestations Mental retardation is characterized by low intelligence and social maladjustment. Intelligence level is generally measured by IQ tests, while the measure of social adaptability is more complex, often related to age, occupational requirements, socio-cultural background and other factors. The degree of mental retardation and the degree of social adaptability do not often coincide, and some people with lower IQs are still socially adaptable, so it is not appropriate to diagnose mental retardation solely on the basis of intelligence level. In the past, mental retardation was categorized into three levels, namely, stupidity, dementia and idiocy, according to the severity of symptoms. The Chinese Classification of Mental Diseases (CCMD) uses a 4-tier classification. I. Mild: IQ of 50-69. accounts for the majority of mental retardation. In the preschool period, intellectual development, speaking and walking are slower than children of the same age. They can barely graduate from elementary school, but cannot enter secondary school, have a good mechanical memory, but have difficulty in understanding and remembering, especially in math. They have little difficulty with everyday language. However, the content of speech is monotonous and childish. Emotional development is also immature, with poor ability to distinguish between good and evil and other moral concepts. There is no special abnormality in physical development, and the patient is able to perform simple labor and learn simple skills under guidance, but lacks initiative. Some patients have hyperactivity. From its personality characteristics can be divided into two categories of stable and unstable; the former is quieter, easy to accept education, master certain skills, still able to adapt to the social environment, easy to get sympathy and care; unstable type, also known as excitable, excited, hyperactive, chattering, lack of self-awareness, poor social adaptation, often annoying or teased. “Quite” in “stupid”. Second, moderate: IQ is 35-49, accounting for about 10-20% of mental retardation. In the pre-school age can learn simple life language, but poor vocabulary, can not express the more complex content, not easy to establish a cohesive relationship with children of the same age, into the elementary school found that its acceptance and comprehension of the children of the same age are poorer than the children, can calculate the addition and subtraction of single-digit and ten-digit numbers, it is difficult to enter the higher grades of learning. After appropriate training, they can learn some simple labor, but they need to be supervised and taken care of, and lack spontaneity. Emotional fluctuations are not easy to control. With a small body and a special face, they can easily be found to have mental retardation, which is equivalent to “dementia”. Third, severe: IQ of 20 ~ 34, accounting for about 1% of mental retardation, found from childhood with physical and motor function developmental delays, grow to adulthood can only reach 4 ~ 5 years old normal children’s intellectual level, completely unable to go to elementary school. After training to learn to eat by themselves and basic hygiene habits, living under supervision, can not carry out productive labor, often accompanied by other congenital diseases, seizures; may be due to infections or physical illnesses and early death. Extremely severe: IQ of 20 or less, very rare, accounting for less than 1% of mental retardation. They are born with physical and neurological abnormalities, and generally cannot learn to walk and talk, but can only make simple sounds similar to calling people. Sensory retardation and inability to avoid danger. Completely unable to take care of themselves. Severe and very severe cases are comparable to the previously diagnosed “idiots”. In terms of personality traits, there are two types: the stupid and dull retarded type and the unrestrained and irritable excitable type. Physical Symptoms: In mild cases, there may be irregularities in the incisal surfaces, misalignment of the teeth, loose, dry skin, and no obvious positive neurological signs. Medium and severe patients have physical and neurological signs, such as generalized developmental disorders; gigantism, dwarfism or morbid obesity; cranial deformities; macrocephaly, pointed head, long head, slanting head, navicular head, etc.; in addition to finger and toe deformities, palmoplantar dermatomal anomalies, widening of the distance between the eyes, auricular deformities, etc.; as well as motor paralysis, hypertonia, ataxia, speech disorders, or deafness, and other neurological signs. Diagnosis and Differential Diagnosis Because there are individual differences in the rate of mental and physical development in infancy and early childhood, it is necessary to combine the detailed parenting history with the family environment and the social environment to make a comprehensive judgment, in addition to referring to the normal child development standards. The diagnostic criteria for mental retardation in the second edition of the Chinese Classification and Diagnostic Criteria for Mental Diseases (CCDC) are as follows: (1) onset of illness before the age of 18; (2) IQ below 70; (3) social adaptation difficulties of different degrees. Diagnostic Criteria for Moderate Mental Retardation: 1) IQ 35-49; 2) Able to master daily life language, but with poor vocabulary; 3) Unable to adapt to ordinary schooling, but can learn to take care of themselves and do simple labor. Diagnostic criteria for severe mental retardation: 1) IQ 20-34; 2) Speech function is severely impaired, unable to communicate effectively; 3) Cannot take care of himself/herself. Diagnostic criteria for severe mental retardation: IQ less than 20; 2, speech loss; 3, total inability to take care of oneself. To diagnose the etiology of this disease, it is necessary to know whether the patient’s parents have any bad habits, whether the mother had viral infections during pregnancy, or other chronic diseases, mental illnesses, etc., whether there is any history of acute or chronic poisoning, exposure to radioactive substances, endemic tendencies and medication, etc. A detailed physical examination should also be carried out. Detailed physical examination, neurological examination, chromosome examination and other relevant auxiliary examinations should also be conducted. Organic brain diseases, schizophrenia and childhood autism should be excluded. Prognosis varies according to the cause and severity of the disease. In mild and moderate cases, intelligence may gradually improve with age, but it is still lower than that of normal people of the same age. The prognosis is related to factors such as brain disorder, low resistance, and low ability to adapt to life, and severe cases usually die early. Treatment I. Mental retardation is difficult to correct once it occurs, so preventive measures include improving the health of young couples; avoiding consanguineous marriages; avoiding childbearing for those with genetic disorders; and carrying out the necessary examinations regularly after pregnancy, such as chromosome examination of decidualized cells in the amniotic fluid and enzymology examination during the 14th to the 16th week of pregnancy, and terminating the pregnancy if necessary. In addition, should also prevent fetal, perinatal and childhood can lead to mental retardation and various diseases or factors. Second, the cause of treatment: If the cause of the disease can be found early, some cases still have the possibility of treatment, such as hypothyroidism can be treated with thyroxine tablets; patients with phenylketonuria should be treated with dietary therapy at an early stage. At present, there is no effective drug to promote intellectual development, some brain cell metabolism drugs may be conducive to the improvement of mental retardation, such as vitamin B6, cerebrofacial, cerebrofacial, cerebral viability. Appropriate antiepileptic drugs should be used for those with epileptic seizures, and antipsychotics such as chlorpromazine and fenestrazine should be used for those with excitatory behavioral abnormalities. Third, education and training: educators should have great patience, starting from simple content, gradually increasing its complexity, and try to cultivate its ability to live independently. Older children should be gradually trained in simple labor skills so that they can be self-reliant in the future. Parents should be made to realize that scolding is harmful to education. Rehabilitation training can be provided to the moderately ill, with the following objectives: (a) to develop the ability to take care of oneself; (b) to develop basic communication skills; (c) to develop social skills and emotional stability; (d) to develop physical-motor skills; (e) to develop learning skills (reading and writing, etc.); (f) to develop skills in domestic and occupational work; and (g) to develop the ability to take care of oneself; and (h) to develop the ability to take care of one’s own needs and to develop the ability to take care of one’s own needs and to take care of one’s own needs and to take care of those who are seriously ill.