• About Adult ADHD

    Prevalence and Symptoms

    Attention deficit hyperactivity disorder (ADHD) is one of the most common childhood disorders that often continues through adolescence and into adulthood. Current research indicates that ADHD has unique diagnostic features in adulthood and does not necessarily represent the same constellation of symptoms as expressed in children. The epidemiology of ADHD over the past 15 to 30 years has established it as affecting about 4-5% of the adult population.1 Manifestations of ADHD include a combination of persistent problems, such as difficulty paying attention, hyperactivity and impulsivity. Adult ADHD symptoms may not be as clear as ADHD symptoms in children. In adults, hyperactivity may decrease, but struggles with impulsiveness, restlessness and difficulty paying attention may continue. Other symptoms of ADHD in adults can include disorganization, anxiety, emotional instability and low stress tolerance (Symptoms of ADHD in Adults). The diagnostic guidelines in the American Psychiatric Association’s Diagnostic and Statistical Manual, Fifth edition (DSM-5) help diagnose ADHD in both children and adults.2 ADHD is commonly accompanied by other psychiatric and behavioral disorders, including conduct disorder, developmental conditions (e.g. dyslexia, autism), tic disorders, depression and anxiety.

    ADHD is a common neurodevelopmental disorder the exact etiology of which is unknown. It is thought to be caused by a complex combination of environmental, genetic, and biological factors and may differ among individuals.3 Evidence from family, twin and adoption studies shows strong genetic contribution to ADHD but not all of the risk is genetic. It is clear that ADHD is also influenced by non-inherited factors and the gene-environment interaction. Studies show that having a biological relative with ADHD as well as pre and postnatal factors such as exposure to lead, tobacco, maternal stress during pregnancy, and low birth weight/prematurity have been most consistently found as risk factors, but none are yet known to be definitively causal. Structural and functional brain imaging studies suggest that brain maturation is delayed by a few years in individuals with ADHD and that disrupted neural functioning in brain regions may underlie ADHD symptoms.4

    Research does not support the popularly held views that ADHD is caused by eating too much sugar, watching too much television, parenting, or social and environmental factors such as poverty or family chaos. While many factors, including these, might worsen the symptoms of ADHD there is no evidence to conclude that they cause ADHD.

    Adult ADHD and Quality of Life

    Some adults with ADHD may be high functioning and may develop adaptive or compensatory skills to mask the problems associated with ADHD. Adults may find work that is well suited to their symptom profile and may excel in certain aspects of their lives, yet they may still experience challenges in other areas of life such as routine/mundane tasks such as paying bills, looking after the house, or developing stable social relationships. Some people with ADHD have fewer symptoms as they age, but some adults continue to have major symptoms that interfere with daily functioning. Many adults with ADHD are not aware they have it — they just know that everyday tasks can be a challenge. Adult ADHD can lead to unstable relationships, poor work or school performance, low self-esteem, and other problems.

    While many adults with ADHD are able to cope with their symptoms, studies have shown that ADHD is associated with certain risks including:

    • Poor academic performance (e.g., lower grade point average and increased rates of grade retention) and lower rates of high-school graduation and post-secondary education
    • Traffic crashes and injuries
    • Negative occupational outcomes such as unemployment or trouble keeping a job, financial problems, and poor work performance
    • High rates of separation and divorce, frequent changes in residence and early parenthood
    • Increased mortality rates primarily driven by deaths from unnatural causes, especially accidents
    • Increases in criminal behavior
    • Increased suicidal behavior

    It is also important to recognize the positive traits and abilities associated with ADHD such as increased creativity, spontaneity, empathy, endless energy, great imagination, and passion for interests.


    1. Kessler RC, Adler L, et al. The prevalence and correlates of adult ADHD in the United States: results from the National Comorbidity Survey Replication. Am J Psychiatry. 2006 Apr;163(4):716-23.

    2. American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, 5th edition. Arlington, VA., American Psychiatric Association, 2013.

    3. Gillig PM, Gentile JP, Atiq R. Attention-deficit hyperactivity disorder in adults. Psychiatry Board Review Manual. Hosp Physician. 2005;9(part 2):1–11.

    4. Friedman LA, Rapoport JL. Brain development in ADHD; Curr Opin Neurobiol. 2015;30:106-11.