Attention Deficit/Hyperactivity Disorder, Adult


  • Adult attention deficit hyperactivity disorder (adult ADHD) is a pattern of behaviors that include inattention and/or hyperactivity or impulsivity. It is present in multiple settings that impair social, academic, or work performance.
  • Complications of adult ADHD include employment, financial, and interpersonal difficulties, as well as increased risk for driving accidents and suicide.
  • Adult ADHD typically begins in childhood and 30–60% will continue to meet criteria as adults.


  • Symptoms include difficulty concentrating, impulsivity, and hyperactivity/overactivity. Impairment in executive functioning and emotional dysregulation are common features.
  • The three main types of ADHD are (i) hyperactivity-impulsivity predominant, (ii) inattentive predominant, and (iii) combined. The combined type is the most common, followed by the inattentive and hyperactive types.


ADHD affects approximately 4.4–5.2% of adults between 18 and 44 years of age (1). ADHD is more common in men than women, who are less likely to be referred for assessment and more likely to be undiagnosed or misdiagnosed.

Etiology and Pathophysiology


  • ADHD appears to have a genetic component, with heritability of approximately 0.8, suggesting that genetic factors would account for about 65% of phenotypic variance.
  • First-degree relatives of persons with ADHD reported to have 4 to 5 times greater risk than general population.

Risk Factors

  • The risk of ADHD is increased among offsprings of mothers who smoked or had obesity and diabetes during pregnancy. Risk is also increased in those who had lead exposure in childhood. It is unknown whether these associations are causal.
  • Premature birth; very low birth weight; and extreme neglect, abuse, or social deprivation also increase the risk as do certain infections during pregnancy, at birth, and in early childhood.
  • Other factors associated with increased risk for ADHD include neurodevelopmental disorders including autism spectrum disorder and learning disabilities.

Commonly Associated Conditions

  • Substance use and substance abuse disorders
  • Mood and anxiety disorders
  • Intellectual disabilities
  • Obsessive-compulsive disorder (OCD)
  • Tic disorders
  • Delayed sleep-wake phase disorder

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