Question 1: What are the early symptoms of mental retardation in children?
Mental retardation in children refers to a variety of functional deficits caused by genetic factors and psychosocial factors before the age of 18. The basic characteristics are that intelligence is significantly lower than the general intelligence level, and at least two aspects of communication, socialization, learning, work, self-care and health show significant maladjustment. According to the ECA survey, the prevalence of mental retardation is close to 1%, with a male to female sex ratio of 1.5:1. The results of our 1987 epidemiological survey show that the prevalence of intellectual disability is 1.268%, with 1.315% for males and 1.220% for females.
The clinical manifestations of mental retardation in children are closely related to the degree of mental deficiency. The degree of mental retardation is determined by clinical examination including the results of intelligence tests and social adjustment ratings. Currently, intelligence quotient (IQ) is commonly used as an indicator for grading mental retardation. An IQ of 100 to 15 is considered normal. Those with an IQ of 70 or less are considered to be mentally retarded. Mental retardation is clinically classified into 4 levels: mild (IQ 50-70); moderate (IQ 35-49); severe (IQ 20-34); and very severe (IQ below 20).
Question 2: What causes mental retardation in children?
There are many causes of mental retardation in children, including two main categories: biological factors and psychosocial factors.
I. Biological factors
1.Prenatal factors
(1) Genetic factors
(1) Chromosomal aberrations: such as Down’s syndrome, fragile X syndrome, chromosomal telomeric region deletion, etc.
(2) Monogenic genetic diseases: many genetic metabolic diseases may lead to mental retardation in children, such as phenylketonuria, mucopolysaccharide storage disease, methylmalonic acidemia, etc.
③ polygenic genetic disorders: polygenic genetic disorders are the result of the joint action of multiple genes, each gene has its own role, the role is small, but the accumulation, the role can not be underestimated, plus environmental factors, if more than the threshold for the onset of genetic variation, it will lead to the disease. Common polygenic genetic disorders of mental retardation such as neural tube malformation, congenital microcephaly, etc.
(2) External harmful factors during pregnancy.
(1) Pathogenic microorganisms: such as rubella virus, herpes simplex virus, cytomegalovirus.
(2) Drug toxins: such as sodium phenytoin, alcohol, smoking, etc.
③Radiation: including various kinds of radiation in life.
④Maternal health condition: such as the mother’s own underlying diseases, such as diabetes, anemia, malnutrition, folic acid deficiency, etc. In addition, the incidence of chromosomal aberrations will increase when the mother’s gestational age exceeds 35 years.
2.Partum factors
Such as intrauterine distress, fetal asphyxia, cranio-cerebral injury, nuclear jaundice, etc.
3.Postpartum factors
Such as low thyroid function, severe malnutrition, heavy metal poisoning (such as lead poisoning and mercury poisoning).
Second, psychosocial factors
Children who grow up in an environment where they are neglected, abused and ridiculed will lead to serious psychological isolation from the outside world and a gradual tendency to self-imposed isolation. If there is a lack of proper guidance and communication, it may lead to mental retardation.