Mental retardation, also known as mental retardation, is a common and highly visible clinical, rehabilitative, psychiatric, educational and social problem that occurs before the age of 18 years when an individual’s developmental period is markedly below the normal level of intelligence for the same age and has significant deficits in socially adaptive behavior.
Clinical manifestations
1.Classification
(1) According to the ICD-10 criteria, mental retardation can be classified into 5 levels according to the level of intelligence (IQ) (regardless of the etiology).
① borderline intelligence: IQ 70-85;
②Mild mental retardation: IQ 50-69;
③ Moderate mental retardation: IQ 35-49;
④Severe mental retardation: IQ 20-34;
(5) Very severe mental retardation: IQ <20.
(2) Classification according to the ability of social adaptive behavior
Adaptive behavior is mainly expressed in social adaptation, maturation and learning ability. Mental retardation is accompanied by deficiencies in social adaptive behavior in addition to mental retardation. According to the level of mental retardation and the degree of social adaptive behavior deficiency, there are four levels.
① Mild: IQ of 50-70 (80%-85%), not easily detected in early stages, may have delayed language development in infancy and early childhood, difficulties in more complex language expression as well as delayed development of motor functions. Except for complex motor coordination difficulties, there are no obvious signs of abnormalities in the development of the somatic and nervous systems. Learning difficulties are usually found in kindergarten or after school, and may gradually appear during school age, barely reaching the level of elementary school graduation.
Although language development lags behind, they can use social language and can take care of themselves. In adulthood, they have a low level of vocational, social and social skills, but lack the ability to cope with environmental changes. They have difficulty in calculating, reading and writing, applying abstract thinking, lacking flexibility and often relying on others. In terms of personality traits, there are 2 main types, namely stable (stable) and unstable (excitable).
② Moderate: IQ of 35-49 (10%-20%), language and motor function development in infancy and early childhood is significantly backward; low learning ability in preschool, can learn to speak, can perform simpler language expression, can not express more complex content. Most play with children significantly younger than their peers. Poor learning ability, rarely progressing to third grade. They have difficulty taking care of themselves and require supervision, and some have physical developmental deficits and neurological abnormalities. Repeated training can perform simple unskilled work.
③Severe: IQ is 20-34 (within 10%), psychomotor development is found to be significantly backward 3-6 months after birth, there may be somatic congenital malformations and neurological abnormalities (cerebral palsy, epilepsy, etc.), poor motor and language skills, and a stupid face. Learning difficulties and poor comprehension. Adults can only learn simple utterances, cannot take care of themselves and have no social behavior.
④Extremely severe: IQ below 20, obvious somatic deformity and neurological abnormality at birth, no language expression ability at all, unable to recognize relatives, generally unable to learn to walk and talk, poor comprehension ability, lack of self-care ability, completely needing others to take care of and completely dependent on others in life.
2. Physical characteristics and neurological symptoms
In addition to mental retardation and social maladjustment, children with moderate, severe or very severe mental retardation often have physical abnormalities and signs, often with the following manifestations.
(1) Delayed growth or poor physical development: height, head circumference, and weight are two standard deviations lower than the standard values for children of the same age.
(2) Facial features: e.g., tongue-stretching dementia, congenital stupidity face, peculiar facial features.
(3) Skin and hair abnormalities, yellowish hair, fair skin, café-au-lait spots, skin depigmentation spots.
(4) Head abnormalities: for example, microcephaly.
(5) Abnormal body odor: e.g., urine odor, musty odor, etc.
(6) Delayed motor development or limb movement disorders: e.g., crossed gait.
(7) Congenital malformations: e.g., auricular malformation, cleft eye, cleft lip and palate, finger and toe and joint malformations.
(8) Sensory organ disorders: visual and hearing impairment.
(9) Delayed or impaired speech development (hearing impairment should be excluded).
(10) Epilepsy, learning difficulties (need to be distinguished from other causes of learning difficulties).
3.Main psychological characteristics
(1) Characteristic features
The personality of most mentally retarded children often shows some tendency to be overly introverted, withdrawn, silent or extroverted, overactive, easily excited and agitated, and provoked. Mentally retarded children often have inert brain nerves, psychological lack of active needs, pursuits and expectations, lack of interest, learning and life without a clear goal.
(2) Perceptual characteristics
The sensory organs have weak perceptual abilities, such as the inability to distinguish between complex colors and forms, and the inability to discriminate between different frequencies of sound. There are also deficits in the differentiation of taste. Weak active sensory ability, narrow perceptual range, slow perception speed, and low perceptual information capacity. Weak ability to distinguish between things. In addition to poor perception of things and objects, the development of recognition of human expressions is also lagging behind.
Mentally retarded children have difficulty in experiencing other people’s expressions because of their late development and differentiation of feelings. They do not observe other people’s expressions in detail, so they have difficulty in recognizing and understanding the environment and situations, and have difficulty in grasping the overall situation and atmosphere, and experience maladjustment.
(3) Memory characteristics
Memory deficits are also one of the major deficits of mentally retarded children. It is characterized by a narrow and small capacity of memory and incomplete memory content. The purpose of memory is poor and the selection function is weak. The ability to remember both intentionally and unintentionally is weak. Weakness in the associative function of memory. Not good at recognition, recall and recollection from connections and relationships.
(4) Thinking characteristics
Backward, superficial and delayed development of thinking, fixed, stubborn and unmotivated thinking. Difficulty in understanding concepts and poor generalization ability. Not good at distinguishing the phenomenon and essence of things and their relationships. The backwardness of thought development is expressed through perception, attention, memory, personality, and emotion. Due to more language deficiencies of mentally retarded children, such as unclear and impaired pronunciation, poor words, words that do not make sense, etc., directly affect their thinking skills and methods; and written language disorders directly affect the development of their thinking to a higher level.
(5) Non-intellectual factors
Low level of psychological needs, low level of activity motivation, unclear purpose, narrow or no interests, emotional indifference, weak will, etc.
(6) Emotional characteristics
Emotions and emotions occur late and develop late in differentiation. Mentally retarded children have unstable emotions and feelings. Rarely do complex emotions appear. Such as a sense of morality, responsibility and obligation. The ability to regulate and control emotions and feelings is weak.
(7) Sick children also often have crooked mouth, finger biting, anxiety, fear, aggression, xenophobia and other manifestations.
4.Early manifestation
(1) Smiling does not appear at the age of one month, not paying attention to other people’s speech, accompanied by motor development lag.
(2) Visual function is poorly developed, more than 3 months of age still do not look around, often misdiagnosed as blind.
(3) Lack of response to sound beyond 2 months of age is often misdiagnosed as deafness.
(4) Poor swallowing and chewing ability makes feeding difficult, and when given fixed things, swallowing is impaired and can cause vomiting.
(5) After 6 months of age, gaze at the hand persists.
(6) Scissor-like gait of the legs when walking after 1 year of age (also often a sign of cerebral palsy).
(7) Mouth movements persist, and sometimes toys such as blocks are often put into the mouth after 1.5 years of age.
(8) After 1.5 years of age, the child often throws things and is not interested in playing with toys.
(9) Drooling after 1.5 years of age.
(10) During waking hours, the mentally retarded child is seen to grind his teeth in a way that normal children are not.
(11) Repeated or continuous stimulation is required to elicit crying, sometimes with a weak cry. The cry is often guttural, shrill or screechy, and has no normal pitch change.
(12) Lack of interest and lack of concentration are two very important characteristics. The lack of interest is manifested by the lack of interest in the surrounding things and the short-lived interest in toys, and sluggish reaction.
(13) Mentally retarded children often show excessive sleepiness and purposeless hyperactivity in infancy.
Diagnosis
Three components are included.
(i) low intelligence quotient (IQ), IQ <70, 2 standard deviations below the population mean (excluding borderline intelligence);
② Defective socially adaptive behavior, below the standard required by society;
(③) low IQ and deficits in socially adaptive behavior began before the age of 18 (within developmental age).