Mental retardation in children

Mental retardation is a condition caused by congenital or early acquired underdevelopment of the psyche with a pronounced lack of intelligence, which makes it difficult or completely impossible for the individual to function adequately socially.

The term “mental retardation” has become generally accepted in world psychiatry over the past two decades, replacing the term “oligophrenia”, which had been widespread for a long time in our country and some other countries.

The term “oligophrenia” is narrower and is used to denote a condition that meets a number of clear criteria.

• Totality of mental underdevelopment with prevalence of weakness of abstract thinking. Expression of violations of prerequisites of intelligence (attention, memory, work capacity) is less, underdevelopment of emotional sphere is less severe.
• Non-progressiveness of intellectual disability and irreversibility of the pathological process that caused underdevelopment.

The concept of "mental retardation" is broader and more correct, as it includes diseases with congenital or early acquired underdevelopment of mental functions, in which a progressive nature of brain damage is noted. Clinically, this is detected only with long-term observation.

Mental retardation is characterized by a marked decrease in intellectual abilities compared to average (often expressed as an IQ below 70-75) combined with a limitation of more than 2 of the following functions: communication, independence, social skills, self-care, use of community resources, maintaining personal safety. Treatment includes education, work with the family, social support.

It is inappropriate to assess the severity of mental retardation solely on the basis of the intelligence quotient (IQ) (e.g., mild 52-70 or 75; moderate 36-51; severe 20-35; and profound less than 20). Classification must also take into account the level of assistance and care required by the patient, ranging from occasional support to high levels of continuous assistance in all activities. This approach focuses on the individual's strengths and weaknesses and their relationship to the needs of the patient's environment and the expectations and attitudes of family and society.

Approximately 3% of the population lives with an IQ less than 70, which is at least 2 standard deviations below the mean IQ of the general population (IQ less than 100); when care needs are taken into account, only 1% of the population has severe intellectual disability (ID). Severe intellectual disability occurs in children of all socioeconomic groups and educational levels. Less severe intellectual disability (in which the patient requires inconsistent or limited care) is more common in groups with lower socioeconomic status, similar to the observation that IQ is more often correlated with school achievement and socioeconomic status than with specific organic factors. However, recent studies have suggested a role for genetic factors in the development of mild cognitive impairment.

ICD-10 codes

In ICD-10, mental retardation is coded under the heading F70 depending on the severity of intellectual disability. The general intellectual index, determined using the Wechsler method, is used as the first diagnostic guideline. The following IQ indicators are accepted for assessing mental retardation:

• indicator in the range of 50-69 - mild mental retardation (F70);
• indicator in the range of 35-49 - moderate mental retardation (F71);
• indicator in the range of 20-34 - severe mental retardation (F72);
• a score below 20 indicates profound mental retardation (F73).

The fourth sign is used to determine the severity of behavioral disorders if they are not caused by an accompanying mental disorder:

• 0 - minimal or no violations;
• 1 - significant behavioral disturbances requiring treatment measures;
• 8 - other behavioral disorders;
• 9 - behavioral disturbances not defined.

If the etiology of mental retardation is known, an additional code from ICD-10 should be used.

Epidemiology of mental retardation

The prevalence of mental retardation among different age groups of the population varies significantly, which explains the importance of the social adaptation criterion when making a diagnosis. The maximum values of this indicator fall on the age of 10-19 years, at which time society places high demands on the cognitive abilities of the population (schooling, conscription for military service, etc.).

The incidence rate of mental retardation worldwide ranges from 3.4 to 24.6 per 1000 people.

Screening

Screening is used for early diagnosis of mental retardation caused by metabolic disorders. Along with phenylketonuria, screening can be aimed at identifying homocystinuria, histidinemia, maple syrup urine disease, tyrosinemia, galactosemia, lysinemia, and mucopolysaccharidoses. A special diet can help avoid or significantly reduce the severity of intellectual disabilities. Preventive measures include improving care for pregnant women, including obstetrics, preventing neuroinfections and traumatic brain injuries in young children, and iodine prophylaxis for people living in iodine-deficient areas.

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Causes of mental retardation

Intelligence is determined by both genetic and environmental factors. Children whose parents have intellectual disabilities are at higher risk for a number of mental (psychological) developmental disorders, although purely genetic transmission is uncommon. Despite advances in genetics that have increased the likelihood of identifying the cause of a patient's intellectual disability, a specific cause remains undetermined in 60-80% of cases. More often, a cause is identified in severe cases. Impaired speech and personal-social skills are more likely to result from emotional problems, psychosocial deprivation, developmental disorders of scholastic skills, or deafness than from intellectual disability.

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Prenatal factors

Mental retardation can be caused by a number of chromosomal abnormalities and genetic metabolic and nervous diseases.

Congenital infections that may cause mental retardation include infections caused by rubella virus, cytomegalovirus, Toxoplasma gondii, Treponema pallidum, and HIV.

Exposure of the fetus to drugs and toxins can cause mental retardation. Fetal alcohol syndrome is the most common cause in this group. Other causes of mental retardation include anticonvulsants such as phenytoin or valproate, chemotherapy drugs, exposure to radiation, lead, and methylmercury. Severe malnutrition during pregnancy can affect fetal brain development, leading to mental retardation.

Intranatal factors

Complications of prematurity or immaturity, CNS hemorrhage, periventricular leukomalacia, breech delivery, forceps delivery, multiple gestations, placenta previa, preeclampsia, and intrapartum asphyxia may increase the risk of intellectual disability. The risk is increased in small-for-gestational-age infants; intellectual disability and low birth weight have the same causes. Very-low-birth-weight and extremely-low-birth-weight infants have varying degrees of increased risk of intellectual disability, depending on gestational age, intrapartum period, and quality of care.

Chromosomal and genetic causes of mental retardation

Chromosomal diseases	Genetic metabolic diseases	Genetic diseases of the nervous system
Cri du chat syndrome Down syndrome Fragile X syndrome Klinefelter syndrome Mosaicism Trisomy 13 (Patau syndrome) Trisomy 18 (Edwards syndrome) Turner syndrome (Shereshevsky-Turner)	Autosomal recessive: Aminoacidurias and acidemias Peroxisomal diseases: Galactosemia Maple syrup disease Phenylketonuria Lysosomal defects: Gaucher disease Hurler syndrome (mucopolysaccharidosis) Niemann-Pick disease Tay-Sachs disease X-linked recessive diseases: Lesch-Nyhan syndrome (hyperuricemia) Hunter syndrome (a variant of mucopolysaccharidosis) Lowe's oculocerebrorenal syndrome	Autosomal dominant: Myotonic dystrophy Neurofibromatosis Tuberous sclerosis Autosomal recessive: Primary microcephaly

Postnatal factors

Malnutrition and psychoemotional deprivation (lack of physical, emotional and cognitive support necessary for growth, development and social adaptation) in children in the first years of life may be the most common causes of mental retardation worldwide. Mental retardation may be a consequence of viral and bacterial encephalitis (including AIDS-associated neuroencephalopathy) and meningitis, poisoning (e.g. lead, mercury), severe malnutrition, as well as accidents involving head trauma or asphyxia.

Causes and pathogenesis of mental retardation

Symptoms of mental retardation

Early manifestations include delayed intellectual development, immature behavior, and limited self-care skills. Some children with mild intellectual disability may not develop recognizable symptoms until preschool age. However, intellectual disability is often diagnosed early in children with severe to moderate disabilities and in association with physical and developmental anomalies or signs of a condition (eg, cerebral palsy) that may be associated with a specific cause of intellectual disability (eg, intrapartum asphyxia). Developmental delays usually become apparent by preschool age. Among older children, low IQ combined with limitations in adaptive behavioral skills is a hallmark. Although developmental patterns may vary, children with intellectual disability are much more likely to show slow progression rather than developmental arrest.

Some children may have cerebral palsy or other motor impairments, delayed speech development, or hearing loss. These motor or sensory impairments may resemble cognitive impairments but are not independent causes. As children grow and mature psychologically, they may become anxious or depressed if they are rejected by other children or if they are distressed by the perception that others view them as different or inferior. Well-designed school programs that include such children in social and academic settings can maximize social integration while minimizing negative emotional reactions. In patients with intellectual disabilities, behavioral problems account for most psychiatric visits and hospitalizations. Behavioral problems are often situational and can usually be identified as a trigger. Factors that predispose to inappropriate behavior include: lack of training in socially responsible behavior, inconsistent discipline, reinforcement of inappropriate behavior, impaired communication skills, and discomfort due to underlying physical impairments and mental disorders such as depression or anxiety. In inpatient settings, additional adverse factors include overcrowding, understaffing, and lack of activity.

Symptoms of mental retardation

Classification of mental retardation

There are many author classifications of mental retardation, which are presented in the relevant publications. In the clinical and pathogenetic differentiation of mental retardation, it is advisable to divide it into the following groups:

• exogenously conditioned, hereditary forms of brain damage not primarily associated with the formation of the anatomical and physiological basis of intelligence;
• mild forms of mental retardation caused by genetic variability in normal intelligence.

Classification of mental retardation

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Diagnosis of mental retardation

When intellectual disability is suspected, psychological development and intelligence are assessed, usually by early intervention or school personnel. Standardized intelligence tests may indicate below-average intelligence, but if the result does not correspond to clinical data, it should be questioned because of the possibility of error; medical conditions, motor or sensory impairments, language barriers, or cultural differences may interfere with the child's performance on the test. Such tests also have a bias toward the average class, but are generally acceptable for assessing intelligence in children, especially older children.

Neurodevelopmental testing, using tests such as the Ages and Stages Questionnaire or the Parents Evaluation of Developmental Status (PEDS), provides a rough estimate of psychological (mental) development in younger children and may be administered by a physician or others. Such measures should be used for screening purposes only and not as a substitute for standardized intelligence tests, which should be administered and performed only by a qualified psychologist. Neurodevelopmental assessment should be performed as soon as developmental delay is suspected. All cases of moderate to severe mental retardation, progressive disability, neuromuscular disorders, or suspected seizure disorders should be evaluated by an experienced pediatrician specializing in neurodevelopmental care or a pediatric neurologist.

Once intellectual disability has been identified, every effort should be made to determine its cause. Accurate identification of the cause may provide guidance on the child's future development, guide educational programs, assist in genetic counseling, and help reduce parental guilt. History (including perinatal history, neurodevelopmental history, neurologic history, and family history) may reveal the cause. An algorithm for evaluating a child with intellectual disability (global neurodevelopmental delay) has been proposed by the Child Neurology Society. Brain imaging (eg, MRI) may demonstrate CNS malformations (such as those seen in neurodermatoses such as neurofibromatosis or tuberous sclerosis), correctable hydrocephalus, or more severe brain malformations such as schizencephaly. Genetic testing can help diagnose conditions such as Down syndrome (trisomy 21) by standard karyotype testing, deletion 5p (cri du chat syndrome) or DiGeorge syndrome (deletion 22q) by fluorescence in situ hybridization (FISH), and fragile X syndrome by direct DNA testing.

Hereditary metabolic diseases can be suspected by clinical manifestations (e.g., hypotrophy, lethargy, adynamia, vomiting, seizures, hypotension, hepatosplenomegaly, coarse facial features, specific urine odor, macroglossia). Isolated delay in general movements (e.g., late sitting or walking) or fine hand movements (poor grasping of objects, drawing, writing) may indicate neuromuscular disorders. Depending on the suspected cause, special laboratory tests are performed. Vision and hearing should be assessed at an early age; examination for lead intoxication is often also justified.

Diagnosis of mental retardation

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Treatment of mental retardation

Treatment and support depend on social skills and cognitive functions. Referral to and participation in an early intervention program in infancy may prevent or reduce the severity of disability due to perinatal brain injury. Realistic and accessible methods of child care should be recommended.

It is essential to provide support and counseling to the family of the sick child. As soon as the diagnosis of mental retardation is confirmed, the parents should be informed and given sufficient time to discuss the causes, effects, prognosis, the child's future education, and the importance of balancing known prognostic factors with negative self-fulfilling prophecies, in which low expectations lead to poor functional outcome. Sensitive counseling is necessary for the family's adaptation. If the family physician cannot provide coordination and counseling, the child and parents should be referred to a center where children with mental retardation can be assessed and their families can be helped by specialists in various fields of medicine and psychology; however, the family physician should continue to provide medical care.

Examination of patients with certain forms of mental retardation

Probable cause	The examination provided
One or multiple minor developmental anomalies, family history of mental retardation	Chromosomal analysis CT and/or MRI of the brain
Hypotrophy, idiopathic hypotension, hereditary metabolic disorders	HIV screening in high-risk newborns Nutritional and psychosocial history Urine and/or blood amino acid testing and enzyme testing to diagnose storage or peroxisomal diseases Muscle enzyme assay SMA12/60 Bone age, bone radiography
Cramps	EEG CT and/or MRI of the brain Determination of the level of calcium, phosphorus, magnesium, amino acids, glucose and lead in the blood
Skull malformations (eg, premature closure of sutures, microcephaly, macrocephaly, craniosynostosis, hydrocephalus), brain atrophy, brain malformations, CNS hemorrhages, tumors, intracranial calcifications due to toxoplasmosis, cytomegalovirus infection, or tuberous sclerosis	CT and/or MRI of the brain Screening for TORCH infections Urine culture for viruses Chromosomal analysis

A complete individual program is developed jointly with the relevant specialists, including teachers. Neurologists or pediatricians specializing in the neuropsychic development of children, orthopedists, and physiotherapists are involved in the treatment of concomitant diseases in children with impaired motor functions. Speech therapists and defectologists, as well as audiologists, provide assistance in case of delayed speech development or suspected hearing loss. Nutritionists can help in the treatment of malnutrition, and social workers can reduce isolation from the outside world. In case of concomitant mental disorders, such as depression, the child may be prescribed appropriate psychotropic drugs in doses similar to those used in children without mental retardation. The use of psychotropic drugs without behavioral therapy and changes in the child's environment is rarely effective.

Every effort should be made to ensure that the child lives at home and is not isolated from the community. The family environment may be either favorable or negative for the child. The family may benefit from psychological support and assistance with the daily care of the child, such as day care centers, visiting aides, or respite services. The living conditions and environment should encourage independence and support learning of the skills needed to achieve this goal. If possible, the child should attend an appropriately adapted day care center or school with peers who are not mentally retarded. The Individuals with Disabilities Education Act (IDEA), a special education law in the United States, stipulates that all children with disabilities must receive adequate educational opportunities, educational programs for them must be as least restrictive as possible, and must ensure maximum inclusion of such children in school and community life. When people with mental retardation reach adulthood, they are provided with a range of housing and employment options. Large institutions where mentally retarded people lived and worked are now being replaced by small group housing or individual apartments that meet their functional capabilities and needs.

Many people with mild to moderate intellectual disability can provide for themselves, live independently, and succeed in jobs that require basic intellectual skills. Life expectancy may be reduced depending on the etiology of the disorder, but medical care improves the long-term health outcome for people with all types of intellectual disability. People with severe intellectual disability typically require lifelong care and support. The more severe the disability and immobility, the higher the risk of death.

Mental Retardation - Treatment

Prevention of mental retardation

Medical genetic counseling allows us to give recommendations on the undesirability of pregnancy in case of hereditary burden of some forms of mental retardation due to the high risk of giving birth to a sick child. During prenatal diagnostics with the help of amniocentesis at the 14-16th week of gestation, metabolic diseases (homocystinuria, maple syrup urine disease, mucopolysaccharidoses) are identified, which, in the presence of a risk of chromosomal abnormalities, allows us to recommend termination of pregnancy.

Seeking medical genetic counseling can help couples at high risk of having a child with mental retardation understand the potential risks. If a child is diagnosed with mental retardation, determining the etiology can provide the family with information about the likelihood of having a child with the disorder in the future.

High-risk couples who decide to have a child often undergo prenatal testing to allow for termination of pregnancy and subsequent family planning. Amniocentesis or chorionic villus sampling can detect inherited metabolic and chromosomal disorders, carrier states, and CNS malformations (eg, neural tube defects, anencephaly). Ultrasonography can also detect CNS defects. Maternal alpha-fetoprotein is a good screening test for neural tube defects, Down syndrome, and other conditions. Amniocentesis is recommended for all pregnant women over age 35 (as they have an increased risk of having a child with Down syndrome) and for women with a family history of congenital metabolic disorders.

Rubella vaccination has virtually eliminated congenital rubella as a cause of mental retardation. Vaccination against cytomegalovirus infection is currently being developed. The incidence of mental retardation is declining due to continued improvements and increased availability of obstetric and neonatal care and the use of exchange transfusion and Rh _o (D) immune globulin to prevent and treat hemolytic disease of the newborn; improved survival of very low birth weight infants is maintained, but the incidence of mental retardation remains unchanged.

Prognosis of mental retardation

The prognosis depends on the etiopathogenetic variant of mental retardation and the socio-psychological conditions of upbringing.

For progressive forms, in which mental retardation is only one manifestation of the disease, the prognosis is poor in most cases. Mental development stops at a certain stage, and a gradual disintegration of acquired motor and mental functions occurs. Death occurs in childhood or adolescence from accompanying infections.

Non-progressive forms of mental retardation are characterized by positive evolutionary dynamics with slow but progressive development of mental functions with the greatest lag in higher forms of cognitive activity - generalization and abstraction. A significant role is played by factors of a socio-psychological nature (family environment, presence or absence of complicating pathocharacterological disorders, timeliness and adequacy of training, acquisition of work skills).

In cases of mild mental retardation, not complicated by mental disorders, in adulthood it is possible to adapt to an environment that does not make special demands on their abstract-logical level.

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