A recent study from Europe showed a differential effect of first time standard ADHD medications on the white matter of children (10-12 years) compared to adults (23-40 years). Methylphenidate is the active ingredient in drugs such as Concerta and Ritalin. The article was published in the scientific journal Radiology.
In the scans below, the orange color marks are areas where increased fractional anisotropy in the white matter was seen in children treated with methylphenidate for ADHD. These changes were not seen in adults treated with medication, raising the possibility that younger children may be more vulnerable to toxicity instead of having beneficial effects on white matter development.
From the lead author, Liesbeth Reneman , “We still need to establish the long-term implications of our findings… we are currently conducting a four-year follow-up study. As we also do not yet know whether these effects are reversible or not, and whether they are related to functional or behavioral changes over a longer period of time, our study highlights the importance for further research on this topic in children and adolescents treated with methylphenidate,”
It’s not known whether the white matter changes are a definitely harmful or beneficial change – or whether it is a bit of both. The changes were asymmetric as well, involving connecting pathways on the left more than the right. The full paper can be found HERE. Some researchers are speculating that the brain changes are a beneficial effect, but the marker studied here (increased fractional anisotropy) has been associated with both positive and negative biological effects (for instance in the stimulation of neuronal connections but also in toxic effects and breakdown of the blood brain barrier).
“What our data already underscores is the use of ADHD medications in children must be carefully considered until more is known about the long-term consequences of prescribing methylphenidate at a young age.
“The drug should only be prescribed to children who actually have ADHD and are significantly affected by it.”
The white matter changes were seen after 4 months of treatment.
There is a high rate of co-occurence of dyslexia and ADD or ADHD. Studies of ADHD subjects show the presence of a reading disability in 18-45%, whereas in samples of test subjects with a reading disability, 18-42% have been observed to meet criteria for ADHD.
A review of these studies can be found HERE.