By Wilfred G. van Gorp, Ph.D., ABPP
ADHD always appears in childhood (before age 12) and in many individuals, persists into adulthood. But how a person acquires ADHD is not definitively known. It does not come from watching too much television, an unhealthy diet alone, or poor parenting. Rather, ADHD is a brain condition with a strong genetic component. Other risk factors include low birth weight, birth complications, and a history of head injury in infancy or childhood. These factors appear to interact during fetal development and result in the patterns of inattention and hyperactivity that characterize ADHD.
Somewhere between one third and three quarters of children who have ADHD in childhood will also exhibit the disorder in adulthood. So the short answer to the question of how you get ADHD is usually: you are born with it.
Is ADHD Genetic?
Yes. ADHD is one of the most heritable conditions in psychiatry. Research consistently shows that genetics account for approximately 70 to 80 percent of the variance in ADHD. If a parent has ADHD, their children have a significantly elevated likelihood of having it as well. Twin studies show that when one identical twin has ADHD, the other is far more likely to also have it than in fraternal twin pairs.
ADHD is not caused by a single gene. It is influenced by many common genetic variants that each contribute a small effect. Researchers have identified several genes involved in dopamine and norepinephrine signaling, the neurochemical systems most closely associated with attention and executive function. This genetic complexity explains why ADHD can look quite different from one person to the next, even within the same family.
ADHD Risk Factors
Beyond genetics, certain environmental and biological factors are associated with elevated ADHD risk. These include premature birth and low birth weight, prenatal exposure to tobacco smoke or alcohol, significant early childhood head injury, and complications during labor and delivery. These factors are thought to interact with underlying genetic vulnerabilities during brain development.
Screen time, diet, and parenting style do not cause ADHD, though they may influence how symptoms are expressed. This distinction matters because it removes misplaced blame from families and directs attention toward accurate assessment and effective support.
How Do You Get an ADHD Diagnosis?
For most parents and individuals, the practical question of how to get an accurate ADHD diagnosis is more pressing than the question of what caused it. Input from teachers and a pediatrician can be a helpful starting point, but the most accurate diagnosis typically comes from a comprehensive neuropsychological evaluation.
A neuropsychological evaluation tests the ability to maintain attention over a sustained period, the ability to divide attention between two or more tasks, and the ability to maintain focus under varying conditions. These tests are verbal and paper-and-pencil in nature and involve nothing invasive. Neuropsychological testing remains the most definitive method for diagnosing ADHD in both children and adults.
ADHD in Adults
Many adults with ADHD were never evaluated as children, either because their symptoms were managed well enough to avoid notice or because understanding of adult ADHD was limited when they were growing up. Adults with undiagnosed ADHD often describe a lifelong experience of struggling to stay focused, manage time, and follow through on tasks despite genuine effort. They are more likely to experience depression, chronic stress, and relationship difficulties than individuals without ADHD.
Getting a diagnosis as an adult is both valid and valuable. An accurate diagnosis opens the door to treatment, and a formal evaluation provides documentation that can support requests for workplace accommodations or extended time on professional licensing exams.
Is ADHD a Disability?
ADHD can qualify as a disability under the Americans with Disabilities Act when it substantially limits a major life activity such as concentrating, organizing, or completing tasks. This means adults with ADHD may be eligible for workplace accommodations, and students may qualify for academic accommodations including extended time. Formal documentation from a neuropsychological evaluation is typically required to access these supports.
How Do You Treat ADHD?
Medications can be very important in treating the inattention and hyperactivity associated with ADHD, as can behavioral treatments and coaching. At the Cognitive Assessment Group, we work with physicians who have special expertise in medications for children and adults with ADHD, and we can provide referrals to these professionals when testing confirms a diagnosis. The most important first step is always getting the right diagnosis.
We welcome you to contact us today for an appointment or for more information about ADHD testing in New York City and Chicago.
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Frequently Asked Questions About ADHD Causes
Yes. ADHD is strongly hereditary. If a parent has ADHD, their children have a substantially elevated likelihood of having it as well. Twin studies consistently show high heritability rates, and researchers have identified multiple genes associated with ADHD risk. Having a family member with ADHD is one of the strongest indicators that an evaluation may be warranted for a child who is showing symptoms.
ADHD is caused primarily by genetic and neurological factors. It is one of the most heritable conditions in psychiatry, with genetics accounting for roughly 70 to 80 percent of cases. Differences in brain development, particularly in the prefrontal cortex and the dopamine and norepinephrine systems, are consistently observed in people with ADHD. Certain biological risk factors such as premature birth or prenatal tobacco exposure can also elevate risk, but these are secondary to genetic influences.
ADHD does not develop for the first time in adulthood. It is a neurodevelopmental condition rooted in early brain development. However, many adults receive their first formal diagnosis later in life because their symptoms were compensated for during childhood or misattributed to anxiety, depression, or personality traits. Adult ADHD diagnoses reflect late identification rather than late onset.
The primary risk factor for ADHD is family history, given the condition’s strong genetic basis. Additional risk factors include premature birth, low birth weight, prenatal exposure to tobacco or alcohol, and early childhood head injury. Contrary to common belief, screen time, sugar, and parenting style do not cause ADHD, though they may affect how symptoms are expressed in a child who already has the condition.
ADHD in adults is diagnosed through a comprehensive neuropsychological evaluation that assesses attention, working memory, processing speed, and executive function using standardized measures. The evaluation also includes a thorough history to establish that symptoms were present in childhood, which is required for an ADHD diagnosis. Importantly, a comprehensive evaluation also rules out other conditions that can mimic ADHD, such as anxiety, depression, sleep disorders, and learning disabilities.
