US Editor: Stas Fridland, 4th Year Medical Student, Northwestern University School of Medicine, Chicago, Illinois
Brief overview
Attention deficit hyperactivity disorder (ADHD) is one of the most common mental disorders in childhood and adolescence, with an estimated prevalence of 10%, and has been receiving increasing media and social attention in recent years.
The etiopathogenesis of ADHD is only partially understood. Genetics contributes up to 80%, whereas the influence of environment, pre- and perinatal problems, and education seems to be relatively small.
The symptoms of ADHD usually begins before the age of 5 and they are characterized by marked inattention, increased impulsivity, and motor hyperactivity. In addition, those affected often show carefree behavior in risky situations, combined with motor clumsiness. ADHD can persist into adulthood, where the hyperactive component recedes into the background, but affective and emotional dysregulation is more pronounced.
Therapy can be medical and/or psychotherapeutic, depending on the severity of the symptoms. In the course of adolescence, an attenuation of the symptoms or a shift in the focus of the symptoms is often observed. In >50% of cases the symptoms persist.
Definition
Attention deficit hyperactivity disorder (ADHD)
According to the International Statistical Classification of Diseases and Related Health Problems (ICD-11),[1] attention-deficit/hyperactivity disorder (ADHD) is characterized by a persistent (≥6 months) pattern of inattention and/or hyperactivity and impulsive behavior that begins in childhood (before the age of 12) and is associated with functional impairment in various areas of life (school, work, social).
Similarly, the U.S. Diagnostic and Statistical Manual of Mental Disorders (DSM-5)[2] characterizes attention-deficit/hyperactivity disorder (ADHD) as a persistent pattern of inattention and/or hyperactivity and impulsivity that is inconsistent with developmental level and interferes with functioning or development.
Epidemiology
ADHD is one of the most common mental disorders in childhood and adolescence with an estimated prevalence of 10% of all children. The symptoms often begin before the age of 5. Symptoms become more problematic upon school entry, among other things because children with ADHD frequently (>30%) show partial performance deficits in reading and spelling. It is assumed that the disorder persists into adulthood in ≥10% of affected individuals (and residual symptoms are present in up to 50% of affected individuals). The prevalence among adults is approximately 3%. There is a male sex predominance in a ratio of about 3:1.
There has long been and continues to be a societal debate about ADHD, with repeated talk of “overdiagnosis” and “overtreatment.” However, the population-based prevalence of ADHD has remained constant for years with the increasing recognition of the developmental disorder. Therapy of the disease is essential.
Etiopathogenesis
The etiopathogenesis is only partially understood, but genetics contributes up to 80%. The concordance rate in monozygotic twins is 50 to 80% and the disease risk in first-degree relatives of affected individuals is increased five-fold. At the genome level, chromosomes 16p13 and 15q appear to play a role in the development of ADHD. The influence of environment, pre- and perinatal problems, and education is small. The child’s psychosocial environment has a major influence on the expression of symptoms and intrafamilial coping strategies.
Imaging studies have demonstrated structural and functional differences between affected and control subjects: Abnormalities were found in the frontostriatal system, among several others. One hypothesis on the pathophysiology is based on the dysregulation (especially reduction) of dopaminergic and noradrenergic neurotransmission. Another hypothesis is based on a dysregulated energy metabolism, which results in deficits in sustained attention: This leads to a compensatory increase in frontal dopamine release, which results in hyperactivity and impulsivity.
Signs and symptoms
Symptoms often begins before the age of 5 and increase with psychological stress. The clinical leading symptoms are inattention (decreased focus, premature stopping and switching of activities, easy distractibility), increased impulsivity (impatience, lack of self-control, interrupting and disturbing others, acting rashly and without thinking), and motor hyperactivity.
These behavioral problems often lead to problems at school, reprimands for rule violations, and rejection by the social environment. Children with ADHD often (>30%) show additional performance disorders such as reading and spelling disorders. The consequences can be depressive reactions and/or social withdrawal. Also often carefree behavior in risky situations is seen, associated with motor clumsiness and thus increased risk of accidents.
From adolescence onwards, those affected have an increased tendency to consume addictive substances and engage in risky behavior. Their performance at school and later at work often falls short of their actual intelligence level. This (self-)awareness can also lead to depressive episodes in the course of time.
Affected adults also frequently exhibit emotional dysregulation with mood swings and repeated brief outbursts of affect. Dissocial tendencies and low frustration tolerance may also occur. Compared to childhood, motor hyperactivity often decreases significantly in adults, while impulsivity and inattention persist, which makes diagnosis in adults difficult.
Regarding the course of ADHD in childhood and adolescence, the following symptom changes can be observed:
