Mental Retardation - Symptoms

Symptoms of mental retardation

Despite the polymorphism of clinical manifestations, two main criteria can be identified, typical for most forms of mental retardation, which characterize primarily the so-called nuclear or typical oligophrenia.

• Underdevelopment is of a total nature and concerns not only the intellectual activity and personality of the patient, but also the psyche as a whole. Signs of underdevelopment are found not only in thinking, but also in other mental functions - perception, memory, attention, emotional-volitional sphere, etc.
• In cases of total mental underdevelopment, the insufficiency of higher forms of cognitive activity - generalization and abstraction - comes to the fore. Weakness of abstract thinking is also reflected in the characteristics of perception, attention, and memory.

The structure of mental retardation may be uneven. In this case, it is not limited to symptoms typical of mental retardation. These include variants with additional psychopathological symptoms in relation to the syndrome of general mental retardation. In this case, one can observe the entire range of mental disorders occurring in intellectually competent individuals, the frequency of which among the specified forms of mental retardation is at least 3-4 times higher than in the general population. Complicating symptoms may be represented by various neurotic and psychopathic disorders, psychomotor disinhibition, cerebral asthenia, psychoses, convulsive and non-convulsive forms of seizures.

Mental retardation is a non-specific condition that is diagnosed according to the DSM-IV criteria. It can be caused by various hereditary and acquired diseases, many of which have characteristic behavioral manifestations ("behavioral phenotypes"). Hereditary diseases that cause mental retardation and characteristic behavioral disorders include fragile X, Turner, Rett, Down, Williams, Prader-Willi, Lesch-Nyhan, Lowe syndromes, etc.

Fragile X syndrome. The disease is caused by a mutation in the form of an increase in the number of repeats of the trinucleotide CGG (cytosine-guanine-guanine) in the promoter region of FMR1 on the long arm of the X chromosome (Xq27.3). A male carrier passes on the premutation to his daughters (but not sons). An increase in the number of CGG repeats with the development of a "full" (disease-causing) mutation occurs during the meiotic cycle in a woman. The full mutation is characterized by hypermethylation of the FMR1 promoter region and an increase in the number of CGG repeats from several hundred to many thousands. Each child born to a female carrier has a 50% risk of receiving a fragile X chromosome carrying the mutation, which can, without clinical manifestations, be transmitted through a number of generations before a child with clinical manifestations of this syndrome is born. In its advanced form, the disease manifests itself in boys. The characteristic phenotypic features of the disease include mental retardation, an elongated narrow face with protruding ears, a massive lower jaw and a high, protruding forehead, gothic palate, strabismus, low muscle tone, flat feet, and macroorchidism. In addition, stereotypies in the form of hand waving or nail biting, an unusual change in speech characterized by rapid fluctuating speech, repetition of individual sounds, words or phrases are often observed. Attention deficit hyperactivity, delayed motor development, phobic avoidance of communication with peers or strangers are also often noted, but quite normal relationships are established with caregivers. Averted gaze is an attention-getting sign often observed in affected boys. In females, a milder form of the disease is observed, which is characterized by symptoms of restrictive behavior or social phobia, as well as learning disabilities, a disorder in the development of mathematical abilities and attention deficit. At the same time, the intelligence quotient (IQ) often remains within the normal range. Thus, fragile X syndrome may be accompanied by symptoms of anxiety, attention deficit, hyperactivity, stereotypies, and sometimes affective disorders.

Turner syndrome. Turner syndrome (Shereshevsky-Turner) is a chromosomal disorder that manifests itself in women as short stature and infertility and occurs due to the complete or partial absence of one of the X chromosomes. Neuropsychological examination of these individuals reveals difficulties in performing tests of visual-spatial functions and solving non-verbal problems. The patients' behavior shows features of immaturity, hyperactivity, "nervousness". They develop poor relationships with peers, have learning difficulties, and attention deficit disorders.

For several decades, patients with Turner syndrome have been receiving estrogen replacement therapy, which promotes the development of secondary sexual characteristics and maintains tissue trophism, including bone trophism. Estrogen therapy also has a positive effect on patients' self-esteem. Somatotropic hormone has recently been proposed for accelerating growth in patients with Turner syndrome.

Down syndrome. The disease was first described by John Langdon Down. In 95% of cases, the disease is associated with strisomy on chromosome 21. It is characterized by the presence of a fold in the area of the inner corner of the eye (epicanthus), flattening of the bridge of the nose, the presence of a single transverse palmar groove, decreased muscle tone, and heart pathology. Patients with Down syndrome are usually sociable and can interact with others. However, they have a pronounced deficit in communication skills, which manifests itself in everyday activities, impaired development of social skills, and poor development of expressive speech (with greater preservation of the receptive aspect of speech). However, the main cause of social maladjustment of patients is early developing dementia. In addition, patients may have dyskinesia and affective disorders.

Williams syndrome. Williams syndrome is a hereditary disorder characterized by a deletion of one or more genes in or near the locus encoding elastin (7qll.23). The disorder is characterized by an "elfin face", cardiovascular pathology, high blood pressure, increased calcium levels in the blood, and behavioral changes. The appearance of patients is quite characteristic - almond-shaped eyes, oval ears, full lips, a small chin, a narrow face, and a large mouth.

Patients with Williams syndrome interact with adults quite easily, but their relationships remain superficial. Often there are attention deficits, increased anxiety, poor relationships with peers, impaired development of visual-spatial and motor skills. In addition, signs of autism, delayed psychomotor and speech development, hypersensitivity to sounds, unusual food preferences, perseverative actions are detected.

Prader-Willi syndrome is caused by a microdeletion on chromosome 15 (15qll and 15ql3 loci), which the patient inherits from the father. The disease was first described in 1956 by Prader as a syndrome characterized by obesity, short stature, cryptorchidism, and mental retardation. Other signs of this condition include obsessive thoughts about food, compulsive eating behavior, a massive trunk, underdevelopment of sexual characteristics, and low muscle tone.

People with Prader-Willi syndrome have delayed speech and motor development, and learning difficulties. Eating disorders are expressed, which include stealing and hoarding food products, gluttony with disorderly consumption of various types of food. Sleep disorders, irritability, irascibility, and an increased pain threshold are often observed. This disease is also characterized by a wide range of stereotypical actions, including scratching the skin, biting nails, picking the nose, biting the lips, and pulling out hair.

Lesch-Nyhan syndrome is inherited as an X-linked recessive disorder and occurs only in boys. It is associated with a congenital disorder of purine metabolism due to the absence of hypoxanthine-guanine phosphoribosyltransferase. The disease is characterized by increased uric acid levels (hyperuricemia), impaired renal function, arthralgia, choreoathetosis, spasticity, autoaggressive actions, mental retardation.

Lesch-Nyhan syndrome is particularly characterized by continuous, severe self-injurious actions. They are quite variable, which is apparently due to internal impulses rather than external influences. Patients are often unable to inhibit their own self-injurious actions, but, sensing their onset, they sometimes ask others to restrain them. Aggression against others in this disorder can be expressed to the same extent as auto-aggressive actions. Studies have shown that stress reduction, tooth extraction, and physical restraint, which are often tried to combat auto-aggressive actions, have little effectiveness. The severity of auto-aggressive actions usually does not change over time. The outcome depends to some extent on the age of onset.

The development of a laboratory model of Lesch-Nyhan syndrome has allowed us to better understand the pathogenesis of autoaggressive actions. Transgenic mice with a deficiency of hypoxanthine-guanine phosphoribosyltransferase did not show any neurological dysfunction. However, after administration of 9-ethyladenine, a neurotropic drug acting in the basal ganglia, these animals developed autoaggressive behavior. Positron emission tomography (PET) studies have revealed a significant decrease in the number of dopaminergic nerve endings and dopaminergic neuron bodies in the brain. Apparently, dopaminergic dysfunction, which is systemic and associated with impaired brain maturation, plays an important role in the development of characteristic mental disorders. Regular administration of a dopamine reuptake inhibitor to healthy adult mice provokes the emergence of autoaggressive behavior, which coincides in time with a 30% decrease in the concentration of dopamine in the striatum, with an increase in serotonin turnover and a significant increase in the synthesis of substance P and neurokinin A. In this case, autoaggressive behavior can be blocked by the administration of dopamine D1- or D2-reuptake inhibitors. These data are consistent with reports of the effectiveness of risperidone in Lesch-Nyhan syndrome.

Cornelia de Lange syndrome. In 1933, Cornelia de Lange, a Danish pediatrician, described two children with similar symptoms: low birth weight, retarded growth, short stature, microcephaly, thin fused eyebrows (synophrys), long eyelashes, a small upturned nose, and thin everted lips. In addition, patients may have hypertrichosis, small hands and feet, partial fusion of the second and third toes (syndactyly), curvature of the little finger on the hands, gastroesophageal reflux, epileptic seizures, heart defects, cleft palate, intestinal pathology, and feeding difficulties.

Most patients with Cornelia de Lange syndrome have moderate or severe mental retardation. Although the type of transmission of this disease has not been definitively established, the offspring of patients with mild manifestations of the syndrome may have a full-blown form of the disease. The behavior exhibits features characteristic of patients with autism, such as poor facial expression of emotions, autoaggressive actions, stereotypes, pleasant sensations during vestibular stimulation or abrupt movements.

Lowe's syndrome. Lowe's oculocerebrorenal syndrome is an X-linked disorder characterized by congenital cataracts, cognitive impairment, and renal tubular dysfunction. This disorder is often accompanied by such inappropriate behavior patterns as stubbornness, hyperactivity, irascibility, and stereotypies.

Mental retardation and auto-aggressive/aggressive actions

Autoaggressive (self-harming) actions in people with mental retardation often include constant banging of the head against the wall, biting, and hitting oneself. Other types of autoaggressive actions are also possible - scratching, squeezing of limbs, falling on the floor. Autoaggressive actions are detected in approximately 5-15% of patients with mental retardation and are often the reason for placing patients in specialized psychiatric institutions. Since these actions often have many causes, when examining a patient, it is necessary to assess the influence of external, medical and psychological factors on them. The initial examination should include a functional analysis of behavioral determinants using abbreviated forms. Concomitant somatic diseases often provoke autoaggressive actions, especially when it is impossible to communicate one's physical discomfort.

Aggression towards other people often accompanies self-harming actions, but can also occur independently of them. Sometimes there are peculiar fluctuations between manifestations of aggression and auto-aggression, when the strengthening of one is accompanied by the weakening of the other.

Associated mental disorders in patients with mental retardation

Children and adults with mental retardation often have concomitant mental disorders. In general, 50% of people with mental retardation are diagnosed with some mental disorder requiring treatment. The high prevalence of mental disorders in this category of patients is explained by various factors: primary disease, genetic predisposition, social instability, unfavorable family environment. It is assumed that people with mild mental retardation develop the same mental disorders as people without mental retardation, while with moderate or severe mental retardation, more specific behavioral disorders and general developmental disorders develop. Identifying the nature of behavioral disorders is crucial for choosing effective therapy. Accurate diagnostics are impossible without obtaining information from parents, teachers, employers, and relatives. Standardized assessment scales are recommended to establish a baseline and track the dynamics of the patient's condition.

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