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What Causes ADHD?

Causes of ADHD


Updated April 22, 2014

What Causes ADHD?

Interview with Patricia Quinn, MD

Patricia Quinn, MD, is a developmental pediatrician with more than 30 years experience working with children and families with ADHD and learning disabilities. She is internationally known and well respected as an expert in the field of ADHD. For the last decade Dr. Quinn has devoted her attention professionally to the issues confronting girls and women with ADHD. She is also the author of numerous books on ADHD. I was fortunate to have the opportunity to ask Dr. Quinn about several ADHD issues including the inheritability of ADHD. The interview is summarized below.

No Test for ADHD

ADHD is not like other medical disorders where a blood test can be performed on a baby’s heel after they are born and we can know for certain that the child has a particular condition. There is no genetic test for ADHD. Research continues to focus on identifying which genes or combination of genes may cause a person to be more susceptible to ADHD.

Causes of ADHD

ADHD is primarily an inherited disorder. It is estimated that 80% of individuals diagnosed with ADHD have inherited the condition. For the remainder of cases ADHD may be the residual result of early brain injury/trauma or other impediment to normal brain development. Exposure to chronic low levels of lead, prematurity, obstetrical complications, cigarette smoke exposure in utero, malnourishment, and illnesses such as meningitis or encephalitis can all result in learning and attention problems. The majority of cases of ADHD, however, are genetically inherited.

Is There a Specific Gene?

To date several gene candidates have been found in families who demonstrate ADHD, however, scientists feel that it is not one particular gene but the interaction of several of these genes and the environment that cause ADHD symptoms to manifest.

Not Sex Linked

ADHD is not a sex linked condition. In other words, ADHD is not occurring only in males and thus passed down only from the father to the children. So often people think -- “It’s the dad who has ADHD and if the dad doesn’t have ADHD then the child can’t possibly have it.” This is inaccurate. It is important to understand that as many mothers may have ADHD as fathers.

Family History

An in-depth family history is often very revealing. Family trees can be created that help identify those family members who display symptoms of ADHD, including those adults who were never diagnosed. Despite the lack of a formal diagnosis, history may reveal that these adults feel they could never settle down, changed jobs frequently, have chronic problems completing projects, organizing their life, etc.

Chances of Occurrence

If one child in the family is diagnosed with ADHD, there is a 60% chance that each additional child will also have it. That is not to say 60% of your kids will have ADHD if one does, rather this means that for every additional child you have there is a 60% chance that that child will also have ADHD.

Understanding Symptoms

It is important to understand that ADHD symptoms may manifest very differently in each child. You may have a boy who has been diagnosed with ADHD and a daughter who is having trouble in school, but you never considered your daughter may also have ADHD because her issues are so different. Girls tend to have problems with attention more than hyperactivity. They also tend to be less disruptive than boys with ADHD. A girl’s ADHD could manifest as daydreaming, difficulty processing information, not following directions, being very distracted, even being shy and withdrawn. When a girl does have the hyperactive component of ADHD, the symptoms often look very different than they do in a boy. The girl may be hyper-talkative, hyper-reactive, crying a lot, slamming doors –- behaviors one may not typically think of as ADHD.

Screening Families

Dr. Quinn is a strong advocate of screening the whole family, including the parents, when a child within the family is diagnosed with ADHD. Understanding that ADHD is a genetically inherited disorder, it is clear that health care professionals need to proactively look for ADHD within families where it has already manifested in order to make certain needed treatment approaches are all in place.

Learn more about The Importance of Properly Diagnosing Parents with ADHD.


Patricia Quinn, MD. Phone interview/email correspondence. January 5 and 27, 2009.

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