About a month ago, we were discussing the ADHD gene SLC6A2. Located on the 16th human chromosome, different variations of this SLC6A2 gene are believed to play at least somewhat of a determining factor as to the genetic predisposition towards attention deficit hyperactivity disorders (ADHD). We saw that this gene was also correlated to anxiety and depression-like symptoms (which commonly occur along many ADHD patients) and that these genetic factors were slightly stronger in girls.
Atomoxetine (Strattera) is a non-stimulant alternative to medication treatment for ADHD. Unlike most stimulant medications, which interfere and regulate the pathways of the neurotransmitter dopamine, atomoxetine acts upon the pathway of the neuro-signaling agent norepinephrine. While dopamine-related stimulant medications for ADHD can worsen accompanying anxiety and depressive-like disorders (extreme caution is necessary when prescribing stimulants if a severe co-illness of anxiety or depression is present alongside ADHD), Strattera has shown to extremely beneficial in the co-treatment of depressive-like illnesses, especially when used alongside the SSRI class of antidepressant drugs.
A recent publication in the journal Neuropsychopharmacology highlights the potential connection between variations of the "ADHD gene" SLC6A2 and the effectiveness Strattera (Atomoxetine) for treating ADHD.
It is important to remember that for most genes, there are slight variations in the different forms within the human population. For most, these small changes in DNA do not result in any major physiological differences, but for some, even a change of one or two units of DNA can make a huge impact on biological functions, such as response to a specific medication. We have previously discussed how both the Catechol O-Methyltransferase (COMT) and CREM genes, may both dictate different dosing levels for ADHD medications.
Based on the SLC6A2 and Strattera study, it appears that individuals with specific gene variations of the SLC6A2 gene had a significantly more positive response to atomoxetine (based on a common behavioral rating process typically used to assess ADHD and related disorders), than were others with different variations of the gene. These effects were seen even when another gene (the CYP2D6 gene, located on the 22nd human chromosome and is responsible for the metabolism of atomoxetine/Strattera) was taken into account.
We will hopefully discuss these findings in more detail later, but the main point to drive home from all of this is the concept of how individual gene variation (i.e., which specific forms of a particular gene one has), can play a major role in predicting whether:
- An individual will even respond to particular drug (such as Strattera for ADHD), and
- Whether that individual's particular forms of these genes predispose him or her to requiring a higher (or lower) than normal dosage level than otherwise physiologically similar individuals to achieve the desired effects.
This blogger personally believes that we have just begun to scratch the surface in investigating the power of gene-medication interactions, and how these interactions will shape the landscape for ADHD treatment.