Gene Testing for ADHD Inattentive

In the very near future, we will not have to guess if we or our children have ADHD Inattentive vs. ADHD Combined type.  We will not be scratching our head over whether we have Aspergers disease of Sluggish Cognitive Tempo.  We will not have to wonder if stimulant medication will improve our symptoms or simply make us anxious or cause or hearts to race.

The reason for this is that there are over 20 genes that determine the symptoms of ADHD and it turns out that one of a combination of these genes can answer all the questions above.  It is foreseeable that soon, psychiatrist will take a sample of DNA from inside our mouths, send it to the lab, and in a few days time will be able to tell us our ADHD diagnosis and the best medicine to treat our ADHD.

Behavioral studies have found that the inheritability of ADHD is over 75%.  Genetic factors account for most of the symptoms of Inattentive ADHD and for the symptoms of the other subtypes as well.  There is one study, however, that suggests that while the presentation of Hyperactive/Impulsive subtype symptoms of ADHD is influenced by the additive effect of multiple gene factors, the symptoms of Inattentive ADHD are the result of a parent passing on a dominant gene for this subtype.

In the future, Gene-environment interactions will also be better understood which is very important as studies indicate that environmental factors, when they play a role in the presentation of symptoms, play an equal role in Inattentive ADD and the other subtypes of ADHD.

Inattentive ADHD has been an elusive diagnosis to pin down.  It is not diagnosed as early as the other subtypes and it is often left untreated for years.  A diagnostic DNA test for Inattentive ADHD would allow us to identify individuals with Inattentive ADHD and would provide us information regarding whether these individuals would benefit from stimulant therapy. 

It is estimated that only 20% of individuals with Inattentive ADHD benefit significantly from stimulant medication.  DNA testing might provide us with information regarding whether these individuals would benefit more from a Norepinephrine reuptake inhibitor such as Stratterra or from an Alpha Adrenergic medication such as Intuniv, or from behavior therapy.

It is exciting to observe the accumulating research into gene testing for ADHD Inattentive and for the other subtypes of ADHD.   The day of an office based DNA test for Inattentive ADHD cannot be far away.

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J Abnorm Psychol. 2010 Feb;119(1):1-17.

Genetic and environmental influences on ADHD symptom dimensions of inattention and hyperactivity: A meta-analysis.

Nikolas MA, Burt SA.

D. Child Adolesc Psychiatry. 2010 Feb 10. [Epub ahead of print]

Molecular genetics of attention-deficit/hyperactivity disorder: an overview.

Banaschewski T, Becker K, Scherag S, Franke B, Coghill D.

Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Postbox 122120, 68072, Mannheim, Germany, Tobias.Banaschewski@zi-mannheim.de.

Rev Neurother. 2009 Oct;9(10):1547-65.

The genetics of attention-deficit/hyperactivity disorder.

Coghill D, Banaschewski T.

Centre for Neuroscience, Division of Medical Sciences, University of Dundee, Centre for Child Health, 19 Dudhope Terrace, Dundee, DD3 6HH, UK. d.r.coghill@dundee.ac.uk