Is ADHD On The Rise? Part Two: What Factors Could Be In Play?
Part One of this Q & A (with myself) focused on the new data released by the CDC suggesting that rates of ADHD may be rising. In Part Two, we focus on possible reasons for this.
So although we don’t know for sure if the rates of ADHD are increasing, it’s possible that they are, and it would be important to determine what factors could be in play?
Right, that could lead to better interventions and preventions.
Isn’t ADHD a genetic disorder? How could it increase if that’s the case?
Well, ADHD has been shown to be highly heritable in studies, such as those that use the twin method. There have also been studies that have shown some association between specific gene markers and ADHD. However, even conditions that are highly heritable can be very sensitive to the environment, and changes in the environment. There’s an old principle to keep in mind: a clinical phenotype (such as ADHD) is the product of genotype (DNA) as it is shaped and affected by the environment.
Does this mean that if there are increases in ADHD, they are not due to genetics?
Most likely — genetic changes in the population often happen over very long periods of time. The kind of increases in rates of ADHD we are talking about are happening over the last ten years.
What kinds of environmental effects are you talking about?
Well, this is speculative. There could be prenatal factors involved and possible toxins that we don’t know about yet. You can refer to brief summaries such as those provided by the National Institute of Mental Health to learn more about what’s currently known. I would speculate that there could also be changes in the social environment. Again, keeping in mind that there is some type of genetic gradient underlying heritable conditions (and not just a genetic mutation or single gene cause), environmental contexts can have a strong effect on how frequently a disorder gets expressed. So, for example, if we have less than optimal educational environments, these could in part increase the expression of symptoms. The same thing applies to the home environment. Keep in mind that I am not saying these are causes of ADHD — these are potential contexts that can influence the extent to which symptoms are expressed or become problematic.
So what’s the bottom line here?
ADHD is highly prevalent. It’s got a biological basis to it. However, if it’s increasing, then we need to look at environmental factors that are either making symptoms worse or more clinically relevant in more kids across the country.
Part Three will focus on what the take-home messages are for parents.Add a Comment