Are There Known Causes of ADHD?

Understanding the Causes of ADHD

Causes of ADHD

The exact cause of ADHD has not been determined. However, ADHD is thought to have a genetic component as it tends to occur among family members. Close relatives of people with ADHD have about a 5 times greater than random chance of having ADHD themselves, as well as a higher likelihood for such common accompanying disorders as anxiety, depression, learning disabilities, and conduct disorder.

An identical twin is at high risk of sharing his twin’s ADHD, and a sibling of a child with ADHD has about a 30% chance of having similar problems. Read more about the inheritability of ADHD.

Boys are three times more likely to be diagnosed with ADHD as children, though this ratio seems to even out by adulthood. It is likely that girls are sometimes overlooked when diagnosing ADHD. Symptoms of ADHD can present differently in females, but doctors and other healthcare professionals are becoming better at recognizing, diagnosing and treating girls and women with ADHD.

Ongoing studies are focusing on identifying genes that may cause a person to be more susceptible to ADHD. Research continues to study the link between ADHD and brain structure, brain chemistry especially related to the neurotransmitters dopamine and norepinephrine (which regulate attention and activity), and differences in function of parts of the brain that affect attention and impulse control.

For some individuals, ADHD is the result of early head trauma and brain injury or other impediment to normal brain development such as prenatal exposure to cigarette smoke, alcohol or harmful drugs, premature delivery, birth complications, or exposure to toxic levels of lead. Children with epilepsy are also at a higher risk for symptoms of ADHD.

There is more clarity on what does not cause ADHD. It is not the result laziness or lack of motivation and discipline. It is not caused by poor parenting, poor teaching, too much television, or too much time spent on fast paced video or computer games –- though these factors may certainly worsen ADHD symptoms.

It has been suggested that refined sugars or food additives may increase the risk of ADHD. Nutrition and diet can affect mood and behavior, as well as brain development in early life. At this point in time, however, no conclusive evidence has been found to support that a change in diet significantly reduces ADHD symptoms. This issue remains an area of interest for researchers.

Additional Reading:

ADHD Risk Factors
ADHD Symptoms
Difference Between ADD and ADHD?
Treatment of ADHD
Wondering If You Have Adult ADHD?


National Institute of Mental Health. Attention Deficit Hyperactivity Disorder. Department of Health and Human Services. National Institutes of Health. 2006.

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