I am currently reading a book by Russell Barkley in which he proposes a new theory of ADHD and it is slow, heavy going. I have reached the chapters where he reviewsother psychologists' theories on executive function. They are filled with terms like "cross-temporal behavioral structures" and "retrospective function utilizing provisional memory." As I say to my patients, the concepts of executive function are useful for describing the symptoms of ADHD, but they aren't very practical in most cases, since complex psychological testing is required to evaluate them.
Given the above statements, I was intrigued to find the summary of an article where developmental specialists used these psychological tests to evaluate the effect of Concerta on executive function in children. They performed a double blind, placebo controlled study on 30 children, 6 to 12 years old. It appears to be a good study, since they first determined each child's best dose, then randomly assigned them either to that dose or placebo for a week. At the end of the week, on therapy, the children underwent the complex testing of different aspects of executive function and were then switched to the other treatment (that is, placebo or Concerta) for the next week. Again, after a week, the testing was repeated and only after the results had been recorded did anyone check to see which were medicated and which were not.
The results were not impressive. The tests of working memory showed no improvement on medicine and the tests on specific aspects of generativity and self-regulation had variable results with improvement on one or two out of several measures of performance. They did show a positive change in "response inhibition" on 2 out of 3 tests performed -- this can be an aspect of self-regulation if it stops the response to emotional content of a situation or quells a physical "fight or flight reaction. (This is particularly interesting to me, since I regard the basic mechanism of ADHD symptoms to be the failure of the pre-frontal cortex to trigger inhibition of the natural response to a distraction when one needs to stay focused.)
All in all, this study reinforces the current practice of evaluating ADHD and its treatment by reviewing symptoms, rather than performing complex psychological tests. Indeed, it would have been interesting to review symptom checklists at the same time the tests were performed to see how effective the Concerta was on a more practical level.