Modern ideas about the mechanisms of ADHD formation

Glossary of terms found in the article:

Etiology - (from Greek aitia - cause and...logy), the doctrine of the causes of diseases. Professional (in medicine) use of the term is as a synonym for “cause” (for example, influenza is a “disease of viral etiology”).

Anamnesis - (from Greek - anamnesis - memory), a set of information about the development of the disease, living conditions, past diseases, etc., collected for the purpose of using them for diagnosis, prognosis, treatment, prevention.

Catamnesis - (catamnesis; Greek katamnemoneuo remember) - the term was proposed by the German psychiatrist W. Hagen. Denotes a set of information about the patient’s condition and the further course of the disease after diagnosis and discharge from the hospital.

Prenatal - (from Latin prae - before and natalis - relating to birth), prenatal. Typically, the term "prenatal" is applied to the later stages of embryonic development in mammals. Recognition before birth (prenatal diagnosis) of hereditary diseases in some cases makes it possible to prevent the development of severe complications in children.

Perinatal period (synonymous with the peripartum period) - the period from the 28th week of pregnancy, including the period of labor and ending 168 hours after birth. According to the WHO classification, adopted in a number of countries, P. p. begins at 22 weeks.

Catecholamines (syn.: pyrocatechinamines, phenylethylamines) - physiologically active substances related to biogenic monoamines, which are mediators (norepinephrine, dopamine) and hormones (adrenaline, norepinephrine).

Mediators , transmitters (biol.), - substances that transfer excitation from the nerve ending to the working organ and from one nerve cell to another.

Synapse - (from the Greek synapsis - connection), the area of ​​​​contact (connection) of nerve cells (neurons) with each other and with the cells of the executive organs. Interneuron synapses are usually formed by the branches of the axon of one nerve cell and the body, dendrites or axon of another. Between the cells there is a so-called. a synaptic cleft through which excitation is transmitted through mediators (chemical synapse), ions (electrical synapse) or in one and other ways (mixed synapse). Large neurons of the brain have 4-20 thousand synapses, some neurons have only one.

Despite the large number of studies conducted to date, the causes and mechanisms of development of attention deficit hyperactivity disorder remain poorly understood. It is known that the etiology of this syndrome is combined. That is, no single etiological factor has been identified for this pathology. Therefore, if the history can establish the most likely cause of the disorders, the influence of several factors influencing each other should always be taken into account. A motley picture of pathological manifestations, reflecting the abnormal development of mental functions, is formed due to the fact that damage occurs in the central nervous system (central nervous system) at different stages of development under the influence of a number of factors.

Most of the data obtained on etiological factors are interrelated in nature and do not provide direct evidence of direct and initial causation. For example, although parents of children with ADHD are more likely to smoke tobacco during pregnancy and pregnant women who smoke are more likely to have children with ADHD, this is not direct evidence that smoking causes ADHD. It is possible that parents of children with ADHD may smoke more than parents of normal children because they are more likely to have symptoms of the disorder themselves. It is the genetic relationship between parents and children that may be more significant here than smoking itself. For this reason, it is necessary to interpret with great caution the interrelated results of the many studies on the causal factors of ADHD.

Despite the fact that final clarity about the causes of the disease has not yet been achieved and it is assumed that many factors influence the development of ADHD, most modern research suggests that neurological and genetic factors are more important.

Brain damage during the prenatal and perinatal periods, according to most researchers, is important in the development of ADHD. But exactly what factors and to what extent are the cause of the development of this syndrome have not yet been established. Thus, the occurrence of ADHD is facilitated by such factors as asphyxia of newborns, maternal use of alcohol, certain medications, smoking, toxicosis during pregnancy, exacerbation of chronic diseases in the mother, infectious diseases, attempts to terminate pregnancy or the threat of miscarriage, injuries in the abdominal area, Rh incompatibility -factor, post-term pregnancy, long labor, prematurity, morphofunctional immaturity and hypoxic-ischemic encephalopathy (C.S.Hartsonghetal., 1985; H.C.Lou, 1996). The risk of developing the syndrome increases if the mother's age during pregnancy is younger than 19 or older than 30 years, and the father is older than 39 years.

In recent years, an important role in the development of ADHD has been assigned to early organic damage to the central nervous system. Moreover, the predominance of this pathology in boys is associated with a higher vulnerability of the brain under the influence of pre- and perinatal pathological factors.

Causes of damage to the developing brain fall into four main types: hypoxic, toxic, infectious And mechanical. There is a relationship between the duration of pregnancy in which the impact of pathological factors on the fetus occurred and the severity of the outcomes. Thus, adverse effects in the early stages of ontogenesis can cause developmental defects, cerebral palsy and mental retardation. Pathological effects on the fetus in later stages of pregnancy often affect the formation of higher cortical functions and serve as a risk factor for the development of attention deficit hyperactivity disorder.

Despite the fact that not all children with ADHD can be diagnosed with organic damage to the central nervous system, pre- and perinatal damaging factors are one of the leading causes in the formation of attention deficit hyperactivity disorder.

The genetic concept of the formation of ADHD assumes the presence of a congenital inferiority of the functional systems of the brain responsible for attention and motor control.

According to the results of studies in the USA and Czechoslovakia, 10-20% of children with ADHD had a hereditary predisposition to the disease. Moreover, the more pronounced the symptoms of the disease, the more likely it is of a genetic nature.

When examining twin pairs aged 4 to 12 years from 1938 families, the diagnosis of attention hyperactivity disorder was established among monozygotic twins in 17.3% of boys and 6.1% of girls, among dizygotic twins - in 13.5% of boys and 7. 3% girls. At the same time, concordance (statistical indicator of the percentage of relatives suffering from the same disorder) for attention deficit hyperactivity disorder in monozygotic twins was equal to 82.4%, in dizygotic twins - only 37.9%. The genetic risk of developing ADHD in monozygotic twins is 81%, in dizygotic twins - 29%, a high percentage was also obtained in adopted children - 58%.

In addition, studies have shown that 57% of parents of children with ADHD experienced the same symptoms during childhood.

According to neuropsychological studies of children with ADHD, deviations in the development of higher mental functions responsible for attention, working memory, cognitive abilities, inner speech, motor control and self-regulation were noted. According to M.B. Denckla and R.A. Barkley, disruption of these executive functions, which are responsible for the purposeful organization of activity, leads to the development of the syndrome.

Adults with ADHD also show similar executive function deficits on neuropsychological tests. Moreover, recent research shows that not only do ADHD siblings of children with ADHD have similar executive function deficits, but even those siblings of children with ADHD who do not have these symptoms appear to have some deterioration of the same executive functions. These findings suggest a possible genetic risk for executive functioning deficits in families of children with ADHD, even when family members do not fully exhibit ADHD symptoms.

The impressive amount of data obtained on this issue further suggests that dysfunction of the prefrontal lobes of the brain (deficits in self-restraint and executive functioning) is a likely basis for explaining ADHD. At the same time, there is no clear localization of the damage; most likely we can talk about diffuse damage, therefore research methods such as electroencephalography and computed tomography often do not reveal disorders.

Neurophysiological and neuromorphological studies have revealed a violation of the formation of functional relationships between the midline structures of the brain, between them and various areas of the cerebral cortex in attention deficit hyperactivity disorder, as well as changes in the motor and orbitofrontal areas of the cortex, the basal ganglia (reduction in the volume of the globus pallidus, violation of the asymmetry of the caudate kernels).

Modern theories consider the frontal lobe and, above all, the prefrontal region as the area of ​​anatomical defect in ADHD. Ideas about this are based on the similarity of clinical symptoms observed in ADHD and in patients with damage to the frontal lobe. Both children and adults demonstrate marked variability and dysregulation of behavior and distractibility; deficit of attention, restraint, regulation of emotions and motivation. In addition, in children with attention deficit hyperactivity disorder, a decrease in blood flow was found in the frontal lobes, subcortical nuclei and midbrain, and the changes were most pronounced at the level of the caudate nucleus.

Changes in the caudate nucleus may be the result of its hypoxic-ischemic damage during the neonatal period, since it is the most vulnerable structure under conditions of blood flow deficiency. The caudate nucleus performs an important function of modulation (mainly of an inhibitory nature) of polysensory impulses, the lack of inhibition of which may be one of the pathogenetic mechanisms of ADHD.

Apparently, the identified structural abnormalities are the morphological substrate for the occurrence of mild cerebral pathology observed in ADHD.

Currently, much attention is paid to disruption of the pathways connecting the cortex with the basal ganglia and thalamus. In accordance with the feedback principle, they form loops or cycles. At least five basal ganglion thalamocortical circuits are currently known, each of which includes different parts of the striatum, thalamus and cortex. Hyperkinetic disorders are associated with dysfunction of the “motor” cycle. However, it is unfounded to suggest that this model underlies ADHD.

No serious motor disorders, any changes in muscle tone, or impaired motor reflexes were found in children with the syndrome.

With this disease, it is more likely to assume violations of cortical relationships, because the systems of attention and working memory, according to J.T. McCracken (1991), are located in the area of ​​the orbitofrontal cortex.
Thus, neurophysiological data are not yet sufficient to support either the basal ganglionic or frontal pathophysiological model.

Neurotransmitter deficiency due to impaired metabolism of dopamine and norepinephrine, which are neurotransmitters of the central nervous system, is assumed to be one of the mechanisms for the development of ADHD. Catecholamine innervation affects the main centers of higher nervous activity: the center of control and inhibition of motor and emotional activity, activity programming, attention system and working memory. It is known that catecholamines perform positive stimulation functions and are involved in the formation of the stress response. Based on this, we can assume that catecholamine systems are involved in the modulation of higher mental functions and that when catecholamine metabolism is disturbed, various neuropsychiatric disorders can occur.

Currently, the involvement of all catecholamine systems in the pathogenesis of ADHD, and not just the dopaminergic system, as previously thought, has been shown.

The catecholamine concept of the formation of ADHD is supported by the fact that symptoms of impaired attention and hyperactivity have been successfully treated for several decades with psychostimulants, which are catecholamine antagonists and change the balance of catecholamines in the body. It is assumed that these drugs increase the availability of catecholamines at the synaptic level, stimulating their synthesis and inhibiting reuptake in presynaptic nerve endings. However, there is evidence of a positive, albeit lesser, response to psychostimulants in healthy children. Therefore, evidence of drug response cannot be used to support neurochemical abnormality in ADHD.

Studies of urinary excretion of catecholamines have revealed differences in their metabolism between children with ADHD and healthy children. However, due to the inconsistency of the results obtained, there is still no clear opinion on the issue of catecholamine metabolism disorders in ADHD.

Cerebrospinal fluid findings suggest decreased dopamine in the brains of children with ADHD. At the same time, the study of blood and urinary metabolites of brain neurotransmitters showed contradictory results.

The reason for this may be not only the clinical heterogeneity of children with ADHD, but also the impermeability of the blood-brain barrier to free catecholamines.

Thus, the available evidence appears to indicate a selective deficiency in the availability of both dopamine and norepinephrine, but this cannot be considered proven at this time.

Unfavorable environmental factors associated with anthropogenic pollution and, above all, microelements from the group of heavy metals, can have negative consequences for the health of children. It is assumed that the intake of lead into the body of children, even in small quantities, can cause cognitive and behavioral disorders, while children 1-2 years old are most susceptible to its toxic effects. Thus, an increase in the level of lead in the blood to 5-10 mcg/dl correlates in children with the occurrence of problems with neuropsychic development and behavior, attention problems, motor disinhibition, as well as a tendency to reduce IQ.

However, even with high lead levels, less than 38% of children have hyperactive behavior. And most children with ADHD do not have elevated lead levels in their bodies, although one study suggests they may have higher lead levels than comparison subjects. Data from many studies indicate that no more than 4% of ADHD symptoms in children are due to elevated lead levels.

Thus, the toxic effects of lead on the central nervous system and mental development of children, and its possible role in the formation of the syndrome, have not yet been proven and require further study.

Dietary factors may also be risk factors and influence the development of ADHD. This primarily applies to artificial colors and natural food salicylates, which can cause cerebral irritation and cause hyperactivity. Removing these substances from food leads to significant improvements in behavior and the disappearance of learning difficulties in most hyperactive children.

Eating excess sugar increases hyperactivity and aggressive behavior. But there is also information of the opposite nature. Thus, E.N.Werder and M.V.SoIanto did not establish a significant effect of high sugar levels on the aggressive behavior of children with ADHD. There was only an increase in attention deficits.

Be that as it may, proper and balanced nutrition is important for school-aged children and especially those with ADHD.

Psychosocial factors. An important role in the formation of attention deficit hyperactivity disorder is played by socio-psychological factors, including intra-family and extra-family factors. The psychological microclimate has a great influence: quarrels, conflicts; as well as alcoholism and immoral behavior of parents, upbringing in single-parent families, remarriage of parents, prolonged separation from parents, long-term serious illness and/or death of one of the parents, different approaches to raising a child among parents and grandparents living with the family . All this cannot but affect the child’s psyche. Peculiarities of upbringing also have an impact - overprotection, selfish upbringing of the “family idol” type, or vice versa, pedagogical neglect can cause a deterioration in the child’s development.

Living conditions and material security also matter. Thus, in children from socially advantaged families, the consequences of pre- and perinatal pathology generally disappear by the time they enter school, while in children from families with a low material standard of living or socially disadvantaged families, they continue to persist and create the preconditions for the formation of school maladaptation .

Therefore, psychosocial factors are controllable factors in the development of ADHD. Therefore, by changing the child’s environment and attitude towards him, it is possible to influence the course of the disease and significantly reduce the influence of medical and biological factors. Unfavorable psychosocial conditions only aggravate the influence of residual organic and genetic factors, but are not an independent cause of the formation of attention deficit hyperactivity disorder; they only provoke further development of the disease, even if it started with mild brain damage in the perinatal period or in the first years of life.

Thus, the approaches developed by various researchers to study the formation of attention deficit hyperactivity disorder mostly affect only certain aspects of this complex problem, in particular neuropsychological, neuromorphological, neurophysiological, neurochemical, unfavorable environmental factors, food, etc. But at the present stage it is possible identify only two groups of medical and biological factors that determine the development of attention deficit hyperactivity disorder: 1 - damage to the central nervous system in the pre-, peri- and early postnatal periods; 2 - genetic factors. All other identified disorders are naturally caused by early organic damage to the central nervous system, heredity, or their conjugate effect. At the same time, psychosocial conditions play an important role in the formation of ADHD, along with medical and biological factors.

Research by N.N. Zavadenko showed that in the formation of ADHD, early damage to the central nervous system during pregnancy and childbirth was important in 84% of cases, genetic mechanisms in 57%. Moreover, in 41% of cases, the formation of the syndrome was determined by the combined influence of these factors.

Any pathopsychological experiment includes observation of the patient, behavior, conversation with him, analysis of his life history, and the course of the disease.

Rossolimo proposed a quantitative method for studying the psyche. Rossolimo's method made it possible to introduce the experiment into the clinic. The experiment began to be actively used in psychiatry. Any pathopsychological experiment should be aimed at clarifying the structure of the pathopsychological syndrome.

Pathopsychological syndrome is a relatively stable, internally connected set of individual symptoms.

Symptom is a single disorder that manifests itself in various areas: behavior, emotional response, and cognitive activity of the patient.

The pathopsychological syndrome is not directly given. To isolate it, it is necessary to structure and interpret the material obtained during the study.

It is important to remember that the nature of the disorders is not specific to a particular disease or its form. He is only typical of them.

These disorders must be assessed in conjunction with data from a holistic psychological study. The difficulty lies in judging why the patient does this or that.

Understanding the pathopsychological syndrome allows us to predict the appearance of the most typical disorders for a given disease. According to the forecast, implement a certain strategy and tactics of the experiment. Those. the style of conducting the experiment is selected, the selection of hypotheses to test the subject’s material. There is no need to be biased.

For the syndromic approach in psychiatry, as in medicine, it is important to determine the essential features of mental disorders, which ensures the completeness of the analysis and the validity of the researcher’s conclusions.

Pathopsychological diagnosis.

The pathopsychological syndrome in schizophrenia, epilepsy, and diffuse brain lesions is well developed. In psychopathy, no pathopsychological syndrome has been identified.

It is necessary to highlight the structure of the pathopsychological syndrome.

The pathopsychological syndrome can change over the course of the disease depending on such characteristics of the disease as: form, duration, time of onset, quality of remission, degree of defect. If the disease began earlier, the disease will affect those areas in which the disease arose. (In adolescence, epilepsy will affect the entire mental sphere and leaves an imprint on the personality).

In schizophrenia: paroxysmal form. There is also a continuously flowing form. With this disease, mental changes are observed.

What needs to be analyzed?

Components of the pathopsychological syndrome.

1. features of the patient’s affective response, motivation, system of relationships - this is the motivational component of the activity
2. an analysis of attitudes towards the fact of the survey is carried out
3. how the subject reacts to the experimenter (flirts, tries to impress)
4. analysis of attitudes towards individual tasks (memory testing), changes in behavior during the experiment.
5. Analysis of task completion, attitude to the result (may be indifferent). Everything needs to be recorded.
6. Analysis of attitudes towards experimenter's assessments.

• Characteristics of the patient’s actions when solving a cognitive task: assessment of purposefulness, controllability of actions, criticality.
• Type of operational equipment: features of the generalization process, changes in the selectivity of cognitive activity (synthesis, comparison operations)
• Characteristics of the dynamic procedural aspect of activity: that is, how activity changes over time (the patient is characterized by uneven performance with cerebrovascular disease).

A single symptom doesn't mean anything.

For differential diagnosis: the psychologist should pay the greatest attention to those symptoms that most reliably allow one to differentiate the pathopsychological syndromes of various diseases. That is, if a situation arises: you need to differentiate between schizophrenia and psychopathy. Need to know what the differences are? Psychopathy is less serious compared to schizophrenia.

For diagnosis, studies of thinking processes and the emotional-volitional sphere are used, and it is important to detect differences in the correlation of symptoms. Schizophrenia is more characterized by a weakening of motivation (they don’t want much), impoverishment of the emotional-volitional sphere, a violation of meaning formation, and there is a decrease or inadequacy, paradoxicality of self-esteem.

All these disturbances are combined with the operational and dynamic aspects of thinking. At the same time, the main thing in thinking disorders is a change in the motivational component. Error correction is not available. Refusal of corrections. They do not have enough motivation to perform the task well.

In psychopathy: brightness and instability of the emotional and motivational components of activity are noted. And sometimes the resulting thinking disorder is also unstable. There are no permanent violations. In this case, emotionally caused errors are quickly corrected (to impress the experimenter). It is necessary to clearly understand what methods allow this to be effectively studied.

For the differential diagnosis of schizophrenia and mental pathology caused by organic disorders in the syndrome, the greatest attention is paid to other symptoms. In addition to the emotional-volitional sphere and thinking, the features of mental performance are analyzed. How quickly does the patient become exhausted? What is the pace of the task? Organic disorders are characterized by rapid depletion.

Pathopsychology (from the Greek pathos - suffering, illness) is a branch of clinical psychology that studies the patterns of disintegration of mental activity and personality traits in comparison with the patterns of the formation and course of mental processes in the norm.

Pathopsychology is one of the intensively and fruitfully developing areas of psychology.

The founder of Russian pathopsychology, Zeigarnik, is a student of Levin, a world-famous German psychologist. She developed the theoretical foundations of pathopsychology, described disorders of mental processes, and formulated the principles of work of a pathopsychologist. Scientific and practical activities were continued by students and followers: Polyakov, S. Ya. Rubinshtein, Sokolova, Spivakovskaya, Nikolaeva, Tkhostov, Bratus and others.

Clinical psychopathology examines, identifies, describes and systematizes the manifestations of disturbed mental functions, while pathopsychology uses psychological methods to reveal the nature of the course and structural features of mental processes leading to disorders observed in the clinic. Although pathopsychology has become more widely used in psychiatric clinics, its methodological techniques are currently used not only in psychiatry. Taking into account changes in the patient’s mental state, changes in his performance, and his personal characteristics become necessary in therapeutic, surgical clinics and other areas of medicine.

Knowledge of pathopsychology is important for psychologists of any specialty and specialization, since a psychologist’s professional communication with people does not exclude meeting with a mentally ill person.

In this regard, it should be emphasized that on the border between psychology and pathopsychology lies a problem that is so relevant for social practice and especially for a number of its areas, as the question of the norm, that is, normal mental development. In pathopsychology, in defining normality and mental health, they usually adhere to the provisions of the World Health Organization; normality is understood as “... not only the absence of disease, but a state of physical, social and mental well-being.”

In pathopsychology, ideas about pathopsychological syndromes of disorders of the cognitive, motivational-volitional and personal spheres in mental illness have been developed (Polyakov, Kudryavtsev, Bleicher, etc.).

According to Korsakova, a “clinical-psychological syndrome” is a naturally occurring combination of symptoms of a disorder of cognitive processes or personality, which is based on the insufficiency of the link that unites them in the systemic-structural structure of the psyche caused by the disease process. The author considers the clinical and psychological syndrome within the framework of two approaches - pathopsychological and neuropsychological. In pathopsychology, the central place is occupied by the search for a common link in the violation of higher mental functions, which underlies the development of individual symptoms during the implementation of such functions. For example, a syndrome-forming radical in schizophrenia may be a violation of motivation, the consequence of which is changes (or features) in thinking, perception, memory, etc., characteristic of this disease.

As Polyakov writes, the clinical-psychological syndrome does not differ from the clinical-psychopathological one, but has a different content. “If clinical (psychopathological) studies reveal patterns of manifestations of disturbed mental processes, then experimental psychological studies must answer the question: how the course (that is, the structure) of the mental processes themselves is disturbed.”

Of a number of psychopathological syndromes, the following are of greatest clinical importance (Bleicher, Kruk):

Schizophrenic or dissociative symptom complex (F20-F29) - consists of such personal-motivational disorders as a change in the structure of the hierarchy of motives, a violation of the purposefulness of thinking (reasoning, diversity, etc.); emotional-volitional disorders (flattening and dissociation of emotions, parabulia, etc.), changes in self-esteem and self-awareness (autism, alienation, etc.);

Psychopathic (personality-abnormal) symptom complex (F60-F69) - consists of emotional-volitional disorders, changes in the structure of the hierarchy of motives, inadequacy of the level of aspirations and self-esteem, disturbances in catathymic type thinking, impairments in forecasting and reliance on past experience (in the clinic - accentuated and psychopathic personality and psychogenic reactions caused largely by abnormal soil) (F43);

Organic (exo- and endogenous) (F00-F09) symptom complexes - consist of symptoms of decreased intelligence, disintegration of the system of previous knowledge and experience, impaired memory, attention, and the operational side of thinking; instability of emotions; reduction of critical abilities (in the clinic this corresponds to exogenous-organic brain lesions - cerebral atherosclerosis (I67.2); consequences of traumatic brain injuries (F06); substance abuse (F13-F19) and other diseases, as well as “endogenous-organic" disorders type of true epilepsy (G40), primary atrophic processes in the brain (G31);

Oligophrenic symptom complex (F70-F79) - consists of the inability to learn, form concepts, abstraction, lack of general information and knowledge, primitiveness and concreteness of thinking, increased suggestibility and emotional disorders.

You should also indicate the symptom complex of psychogenic disorganization, characteristic of reactive psychoses (F23).

Pathopsychological syndrome plays a significant role as a link in nosological and functional diagnostics.

Pathopsychology is a psychological science, and therefore its problems, prospects and achievements cannot be considered in isolation from the development and state of general psychology, psychological knowledge in general.