Attention-deficit hyperactivity disorder overview

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Charmaine Patel, M.D. [2], Haleigh Williams, B.S.

Attention-deficit hyperactivity disorder Microchapters
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Patient Information
Overview
Historical Perspective
Classification
Pathophysiology
Causes
Differentiating Attention-Deficit Hyperactivity Disorder from other Diseases
Epidemiology and Demographics
Risk Factors
Natural History, Complications and Prognosis
Diagnosis
Diagnostic Criteria
History and Symptoms
Psychiatric Examination
Laboratory Findings
Imaging Findings
Treatment
Medical Therapy
Psychotherapy
Brain Stimulation Therapy
Cost-Effectiveness of Therapy
Monitoring Response to Therapy
Future or Investigational Therapies
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Overview

• Attention-deficit hyperactivity disorder (ADHD) is a neurobehavioral brain disorder marked by an ongoing pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or development. It may negatively impact the patient’s academic or professional performance and/or social interactions.
• ADHD has a strong component of heritability.
• ADHD is more commonly diagnosed in boys than in girls, though this may be because the symptoms of the disorder are less easily recognized in girls.

Historical Perspective

• ADHD symptoms have been recognized in children and described in medical texts since the nineteenth century, though the formal diagnosis had not yet been devised.
• ADHD was first included in some form in the DSM in its second edition, when it was referred to as “hyperkinetic reaction of childhood.” It was not until the third edition of the DSM was released in 1980 that the disorder was formally identified as “ADD (Attention-Deficit Disorder) with or without hyperactivity.”
• Rhode Island physician Dr. Charles Bradley pioneered the use of medications to treat ADHD in 1937. Since that time, the prescription of stimulants has become a first-line treatment for ADHD.

Classification

ADHD may be classified according to the DSM-V criteria into three subgroups:

• predominantly inattentive type;
• predominantly hyperactive-impulsive type; and
• combined type.

Pathophysiology

• ADHD appears to be highly heritable, although one-fifth of all cases are estimated to be caused by trauma or exposure to toxins.
• Evidence suggests that ADHD is a heterogeneous disorder, meaning that several causes could create very similar symptomology.
• Although there is evidence for dopamine abnormalities in ADHD, it is not clear whether abnormalities of the dopamine system are a molecular abnormality of ADHD or a secondary consequence of ADHD.

Causes

There are no established causes of ADHD. Studies suggest that ADHD results from a complex interaction between genetic and environmental factors.

Differentiating Attention Deficit Hyperactivity Disorder from other Diseases

• ADHD must be differentiated from other diseases that cause behavioral issues and anxiety such as anxiety disorder, dissociative disorder, conduct disorder, and oppositional defiant disorder.
• ADHD must also be differentiated from the other psychiatric disorders with which it shares common genetic roots, including autism, bipolar disorder, major depression, and schizophrenia.

Epidemiology and Demographics

• The prevalence of attention-deficit hyperactivity disorder (ADHD) is estimated to be 5,000 per 100,000 (5%) children and 2,500 per 100,000 (2.5%) adults.
• Boys are more commonly affected by ADHD than girls. The male to female ratio is 2 to 1.

Risk Factors

Common risk factors in the development of attention-deficit hyperactivity disorder (ADHD) are:

• child abuse;
• infections;
• epilepsy; and
• traumatic brain injury.

Natural History, Complications and Prognosis

• If left untreated, patients with ADHD may experience negative social consequences, such as isolation from and difficulty communicating with friends and loved ones.
• Patients are unlikely to experience any physical problems as a direct result of ADHD.

Diagnosis

The diagnosis of ADHD is made based on the DSM V criteria, which can be found on the Attention-deficit hyperactivity disorder diagnostic criteria page.

History and Symptoms

• The most common symptoms of ADHD include chronic and long-lasting hyperactivity, impulsivity, and inattention.
• It is particularly important to collect a family history with regard to psychiatric disorders, as ADHD has such a strong genetic component.
• It is also vital to understand how long the patient has been experiencing symptoms of ADHD, as the DSM V stipulates that symptoms must have been present for at least 6 months in order for a diagnosis of ADHD to be made. Similarly, an adult cannot be diagnosed with ADHD unless his/her symptoms were present prior to the age of 12 years.

Treatment

Medical Therapy

First line treatments include stimulant medications such as methyphenidate and dextroamphetamine. More recent, less addictive medications used is modafinil. Behavioral modification and strategies have also been shown to help, as pharmacologic treatment is thought to mostly help symptoms associated with poor concentration. Methods of treatment usually involve some combination of medications, behavior modifications, life style changes, and counseling.