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Dr. Kacir's ADHD Blog

ADHD prevalence

Is ADHD genetic or developmental?

One of my patients asked the question in the title of this post.   He also asked if the genetic cause was a mutation.  After I answered him, I thought that my readers might be interested in my reply, so I have cut and pasted it below. 
 
ADHD is clearly inherited genetically since it is passed down from one generation to the next as reliably as height is.  It is a general rule that boys grow to be about 4 inches taller than the average of their parents' heights and girls to be 4 inches shorter.  In the case of height, there are known exceptions, some because of genetic issues (like dwarfism) and others because of developmental or environmental events like accidents or malnutrition.
 
Several genes have been associated with ADHD.  They are not mutations any more than brown eyes are mutations of green eyes.  The one gene that I remember is called DR4.  It is one of at least 6 different sequences that code for a Dopamine Receptor.  More people with ADHD have this particular gene than do people without ADHD.  However, not everyone who has this gene also has ADHD and not everyone with ADHD has this gene.
 
This is probably where the developmental part comes in.  It has been shown that young children have more symptoms of ADHD immediately after watching Spongebob Squarepants than they do after watching Sesame Street.  It is possible that young children who are exposed to a lot of electronic media might be more likely to have enough symptoms to be diagnosed with ADHD than children who spend a lot of time reading or playing with blocks.
 
There is also the fact that while only 4.4% of adults can be diagnosed with ADHD, about 50% of the population in prison can be so diagnosed.  This means more people who made the choice to do illegal activities (and got caught) exhibit ADHD than those who chose to obey the law.  Most of these choices are made during adolescence and can be considered "late developments."  It is clear that ADHD is associated with conduct disorder (a developmental issue that leads to problems with law enforcement) but conduct disorder can also occur without ADHD, so there may be reciprocal effects.  This would be another example of development affecting the expression of a genetic tendency to ADHD.
 
To summarize, genes are responsible for the possibility of having ADHD symptoms.  Environment and development probably determine whether an individual will have enough of those symptoms to match the full requirements of the diagnosis. There are
many genes involved and it is likely that certain variations of these genes are more common in ADHD.  Therefore if more of these genes are the ADHD type in a given person, then that person will have more symptoms of ADHD.

Treating ADHD in jail

I just finished reading the summary of a study in which male prison inmates with ADHD were treated with Concerta.  This is a useful study because ADHD has been shown to be very common in convicts.  While the prevalence of ADHD among
U.S. adults is 4.4%, it is over 50% in the prison population!
 
This sudy was well designed with 5 weeks of double-blind-placebo-controlled research, followed by active treatment and open evaluation for an additional 47 weeks.  Inmates were assessed for symptoms of ADHD and their global functioning on a regular basis throughout the year.
 
There were no significant adverse effects during the course of the study, nor was placebo found to be effective.  Treated inmates showed a marked reduction in their ADHD symptoms and reported significantly improved functioning in their daily activities during the first five weeks.  These positive results continued to improve over the non-blinded extension of the treatment.
 
The conclusion of the authors of this study was that Concerta was an effective treatment for prison inmates with ADHD.  It would be even more significant if treated inmates were found to have less negative behaviors than their untreated peers, were eligible for parole earlier and were less likely to return to jail after release.  Findings such as these would justify ADHD treatment at taxpayer expense.

ADHD and the National Survey on Children's Health

The "Morbidity and Mortality Weekly Report" is an excellent resource for statistics about the health of U.S. Citizens.  It recently reviewed the results of the 2007 National Survey on Children's Health (NSCH) and compared them to those from a similar survey performed in 2003.  According to their parents, 22% more children had been diagnosed with ADHD!  The rise in diagnoses was highest for teenagers from 15 to 17 years old.  It is not clear why the rate has increased so significantly.  Some people think that there is less stigma attached to the diagnosis now while others feel that clinicians got better at recognizing and treating ADHD.  It will be interesting to see whether the rise continues in the next NSCH and to continue to study the results of this one.
 

ADHD in the United States

A national telephone survey of parents between April, 2007 and June, 2008 revealed that 9.5% of children aged 4-17 years had been diagnosed with ADHD.  According to the parents, 66% of these children were taking medication to treat their symptoms.  In 2003, a similar survey found that 7.8% of these children had ever been diagnosed with ADHD.
 
I became aware of the article describing the survey through a physician discussion forum, where one of the more vocal doctors (an orthopedic surgeon) derided the findings.  He argued that the diagnosis was vague since it didn't rely on objective findings like laboratory tests.  Then he said that ADHD was being diagnosed more often because drug companies were interested in selling more drugs to parents who weren't properly disciplining their children.  I obviously disagree with these arguments, but I thought it would be interesting to post them here for reactions.
 
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