Causes and Risk Factors for Attention Deficit Hyperactivity Disorder (ADHD or ADHD)

Attention deficit hyperactivity disorder is a common disease, which is studied by both doctors and psychologists and educators. Manifestations in children are quite bright, these are extreme mobility, inattention, impulsivity and others that cause parents a lot of trouble.

According to epidemiological studies, 4-12% of school-age children suffer from hyperactivity, according to other data, it ranges from 2.0 to 18.0%. The indicator has a wide range of values, since the assessment involves the subjectivity of diagnostic criteria, the opinion of parents, doctors and even teachers is taken into account, and the child’s behavior may change depending on the situation. It is believed that ADHD occurs 3-4 times more often in boys, but it is possible that this is due to their more noticeable aggressive behavior, and inattention in girls is much less often accompanied by destructive behavior. Symptoms decrease with age (up to 65% experience partial recovery), but only 15% of children with ADHD show complete remission in terms of both symptoms and functional impairment.

In addition, if earlier ADHD was considered a disease of childhood, the results of modern studies confirm that the symptoms of ADHD in varying degrees of severity occur in adulthood from 2.5 to 3% of cases. And they can give functional impairments, such as problems in social and family life, low education, low self-esteem, deterioration in emotional development, professional problems, as well as anxiety disorder, disorders associated with the use of psychoactive substances, criminal behavior, a tendency to depression and others.

Causes of ADHD. For decades, many scientists have been looking for the cause of attention deficit hyperactivity disorder. Back in 1845, the German doctor Heinrich Hoffman described a boy with symptoms of the disease and gave him the nickname “Fidget Phillip”. Further, in 1902, the English physician GF Still published a lecture in which he connected hyperactivity with a biological basis, and not with poor education, as was tacitly assumed at that time. By observing a group of children , he was able to very accurately identify the features of ADHD, which still remain relevant today. These features are: hyperactive disorder is more common in boys; the maximum existing violations are manifested in the first years of schooling; family predisposition indicates the role of heredity in its development; ADHD can be formed as a result of damage to the central nervous system; among relatives of hyperactive children, cases of delinquency, alcoholism and depression are more common.

Many doctors and scientists have studied this disease, pointing to genetic mechanisms, organic brain damage and psychosocial factors.

In recent years, significant progress has been made in understanding the neurobiological basis of ADHD. Research on genetic mechanisms, neurophysiological, neuromorphological and neurotransmitter disorders is being widely conducted. Such manifestations as a violation of attention, control functions (self-regulation, planning, self-control and self-esteem), information processing processes and a lack of control over impulses are due to the following mechanisms:

– dysfunction of the frontal lobes of the brain, primarily the prefrontal region,

– violations in the cortex of the parietal lobe of the brain,

– dysregulation of monoamines,

– violations of the functioning of the fronto-striatal systems,

– decrease in metabolism in the prefrontal cortex, in the anterior cingulate gyrus, subcortical nodes.

The genes that determine the predisposition to the development of ADHD, which regulate the metabolism of neurotransmitters in the brain, in particular the genes of the dopaminergic and noradrenergic systems, have been identified.

Risk factors. It is known that the development of many cases of ADHD is based on hereditary predisposition and damage to the developing brain during pregnancy and childbirth (that is, pre- and perinatal pathological factors), leading to impaired development of the central nervous system.

When studying a group of children with ADHD aged 5-13 years ( Zavadenko N.N.), the hereditary nature of the disease was confirmed in 57% of patients. Indications of signs of early organic damage to the CNS were found in 84% of the examined. Violations of the course of pregnancy or childbirth were noted in 84% of cases, and in 56% of cases a combination of the influence of pathological factors both during pregnancy and childbirth was revealed.

According to another study (Morozova E.A., Madyakina A.A.), 70.4% were found to have a burdened perinatal period (the period from the 28th week of pregnancy, including the period of childbirth and ending 168 hours after birth), the threat of abortion (59, 8%) in combination with the use of hormonal drugs (21.3%), toxicosis (45.9%), anemia (45.9%), stress (26.2%).

Maternal smoking during pregnancy has been widely studied as a risk factor for ADHD. Smoking during pregnancy puts the fetus at risk for birth complications, including low birth weight, and also puts the fetus at risk of hypoxia associated with ADHD. Children whose mothers smoked during pregnancy have an increased risk of the disease by 2.4 times. According to foreign literature, smoking and alcohol consumption play a significant role in the development of impaired attention and activity in children.

Some environmental risks are related to exposure to toxins, nutritional deficiencies, or injury. Many studies have examined the effects of iron and zinc on ADHD, as both are required for the production of norepinephrine and dopamine in the brain. Studies have found that indicators of iron deficiency have been associated with ADHD. They also found that ADHD was associated with low levels of zinc in the blood. Among the many toxins studied in ADHD patients, the most compelling evidence points to lead contamination.

ADHD is a hereditary , multifactorial disorder in which genetic factors—often combined with environmental factors—form risk factors for the disease. The mechanisms underlying ADHD are complex and can be identified at different levels.

Although we have a long way to go before we can fully understand the etiology of ADHD, a lot of progress has already been made. We can be sure that part of the risk of ADHD is inherited and that risk variants combine and interact with environmental risk factors to create the pathophysiology of the disorder. In the coming decades, scientists will discover more common and rare genetic and environmental risk factors. This process will lay the groundwork for discoveries that will improve treatment and possibly lead to preventive measures.

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