Inattentive ADHD is Different

Inattentive ADHD is Different

Those of us who have Inattentive ADD or have children with Inattentive ADD know that we and our kids behave fundamentally differently from people who have Hyperactive or Combined type ADHD.  To me, ADHD Inattentive feels different to the core but until fairly recently not everyone even believed the symptoms of Inattentive ADHD were different from the symptoms of Combined Type or Hyperactive Type ADHD.

Fifteen years ago Russell Barkley was the first ADHD researcher to speak of  the difference between the three types of ADHD and in the last few years other ADHD researchers have taken a deeper look.  Scientists are finding biological, even cellular differences between the ADHD types.

The researchers of a new study that was published last month in the Journal Frontiers in Molecular Neuroscience found chromosomal differences between ADHD children of different types.  The researchers performed a study where they looked at a piece of genetic material called a telomere in nine year old kids with ADHD.  What they found was that the length of the telomere was shortened in the Combined type kids but not in the Inattentive kids. 

You have maybe heard of telomeres.  What are they?  In short, telomeres are chromosomal "caps".  Like a the plastic cap at the end of our shoe laces, our telomeres keep our DNA filled chromosomes from unraveling. .

To further the biology lesson...  Our DNA contains the codes that make our bodies work. Our Chromosomes are made of DNA molecules that are wrapped  with proteins and then capped  with telomeres to keep the DNA from unraveling.  The cap or telomere is important because unraveled DNA does not work properly. Telomeres shorten as we age but stress, depression, illness, poor nutrition, lack of exercise and other life style factors  (drug and alcohol use, smoking), speed up their shortening. 

I always wonder when I read studies such as this one about the "chicken and the egg" questions.  Do kids with Combined type ADHD have shortened telomeres because they were born that way or does the stress of having Combined type ADHD (and all the co-conditions that go along with that diagnosis such as depression, etc) cause their telomeres to shorten?

I also wonder about nutrition and exercise.  Lots of studies have shown that we can protect the length of our telomeres by eating better, being at a normal weight and exercising. Might this be the reason that diet and exercise have been found to be beneficial for the treatment of ADHD?

Genetics plays a huge role in ADHD.  We know that ADHD is very inheritable and that other genetic components also contribute to the condition.  I have written a post on one of these components, Epigenes, that gives further insight on the importance of genetics and the environment as it relates to ADHD symptoms.

There is much more to learn about the differences between the ADHD types.  Any study or research work that furthers our knowledge of this condition is helpful to our overall understanding.  It is exciting to me that the pace of research into this topic appears to be quickening!

Frontiers in Molecular Neuroscience. 2015 Jul 10;8:28..

Telomere length is highly inherited and associated with hyperactivity-impulsivity in children with attention deficit/hyperactivity disorder.

Costa Dde S¹, Rosa DV¹, Barros AG¹, Romano-Silva MA¹, Malloy-Diniz LF¹, Mattos P², de Miranda DM¹.