ADHD stands for attention deficit hyperactivity disorder, a condition with symptoms such as inattentiveness, impulsivity, and hyperactivity. The symptoms differ from person to person. ADHD was formerly called ADD, or attention deficit disorder. Both children and adults can have ADHD, but the symptoms always begin in childhood. Adults with ADHD may have trouble managing time, being organized, setting goals, and holding down a job.
The meaning of ADHD is complex. It’s a misunderstood neurological disorder that impacts the parts of the brain that help us plan, focus on, and execute tasks. ADHD symptoms vary by sub-type — inattentive, hyperactive, or combined — and are often more difficult to diagnose in girls and adults. Here, we review the symptoms, causes, types, and tests associated with attention deficit hyperactivity disorder.
ADHD stands for attention deficit hyperactivity disorder, a complex brain disorder that impacts approximately 11% of children and almost 5% of adults in the U.S. ADHD is a developmental impairment of the brain’s executive functions. People with ADHD have trouble with impulse-control, focusing, and organization.
Neuroscience, brain imaging, and clinical research tell us a few important things: ADHD is not a behavior disorder. ADHD is not a mental illness. ADHD is not a specific learning disability.
ADHD is, instead, a developmental impairment of the brain’s self-management system. Common ADHD symptoms include:
Many patients and clinicians describe ADHD as an iceberg, where most symptoms lay hiding under the surface — out of sight but ever present. If you think you or a loved one might have ADHD, take one of our free, anonymous tests below to see if you should seek a formal diagnosis.
“Attention deficit” is, some experts assert, a misleading name. “Attention deregulation” might be a more accurate description since most people with ADHD have more than enough attention — they just can’t harness it in the right direction at the right time with any consistency. And so individuals with ADHD hyperfocus and lose track of time, or misplace their keys, or blurt out an unrelated thought when their focus breaks free from its chains.
The causes of ADHD remain somewhat unclear. Research suggests that genetics and heredity play a large part in determining who gets ADHD. However, scientists are still investigating whether certain genes, especially ones linked to the neurotransmitter dopamine, play a defined role in developing ADHD.
Additional research suggests that exposure to toxins and chemicals may increase a child’s risk of having ADHD.3
ADHD is not caused by bad parenting, too much sugar, or too many video games. ADHD is a brain-based, biological disorder. Brain imaging studies and other research show many physiological differences in the brains of individuals with ADHD.4
The Diagnostic and Statistical Manual of Mental Disorders (DSM)5 previously identified three types of ADHD:
People with hyperactive-impulsive subtype of ADHD act “as if driven by a motor” with little impulse control — moving, squirming, and talking at even the most inappropriate times. They are impulsive, impatient, and interrupt others.
People with the inattentive subtype of ADHD are easily distracted and forgetful. They may be daydreamers who lose track of homework, cell phones, and conversations with regularity.
Individuals with combined-type ADHD display a mixture of all the symptoms outlined above.
These subtypes are now considered “presentations” in the most recent version of the DSM, the DSM-V. Researchers determined that people often move from one subtype to another. For example, a child may present as primarily hyperactive-impulsive in preschool, and lose much of the hyperarousal in adolescence to fit the primarily inattentive presentation. In college and adulthood, the same individual may transition to combined presentation.
The subtypes were primarily based on overt behavioral symptoms, and ignored less visible symptoms like emotional dysregulation, cognitive patterns, and sleep difficulties. Behavioral symptoms imperfectly capture the defining features of ADHD. Non-behavioral characteristics are increasingly recognized in research and diagnosis.
The symptoms of ADHD are spelled out in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-V), which lists nine symptoms that suggest ADHD–Primarily Inattentive and nine that suggest ADHD–Primarily Hyperactive/Impulsive. A child may be diagnosed with ADHD only if he or she exhibits at least six of nine symptoms from one of the lists below, and if the symptoms have been noticeable for at least six months in two or more settings — for example, at home and at school. What’s more, the symptoms must interfere with the child’s functioning or development, and at least some of the symptoms must have been apparent before age 12. Older teens and adults may need to consistently demonstrate just five of these symptoms in multiple settings.