View Full Version : Study: Long Term Effects of Stimulants on Children with ADHD

12-05-13, 06:30 PM
I came across this study today, which struck me as interesting:


Attention-deficit/hyperactivity disorder (ADHD) is a common behavioral and neurocognitive disorder in school-age children. Methylphenidate (MPH) is the most frequently prescribed CNS stimulant for ADHD. The aim of this study is to evaluate the changes in intelligence quotient and domains of neurocognitive function after long-term MPH treatment of Taiwanese children with ADHD.


Taiwanese children with ADHD had lower Verbal IQ (VIQ) and Full IQ (FIQ) and performed poorly on several subtests of the WISC-III, including Similarities, Vocabulary, and Coding, compared to healthy children without ADHD. After one year of MPH treatment, significant decrements in all scores of the ADHD-Rating scale and CGI-S and increments in several domains of the WISC-III, including FIQ, VIQ, PIQ, Perceptual Organization Index (POI), Picture Completion, Picture Arrangement, Object Assembly, and Digit Span were observed. When the ADHD children under MPH treatment were subdivided into two age groups (6--8 years and 9--12 years), significantly better performance in some subtests and subscales of the WISC-III (such as Similarities, Comprehension, and Object assembly) was found in the 6--8 years age group.

I haven't had a chance to read the full study yet, but it struck me for a couple of reasons.

One is that it states directly that the children with ADHD had lower IQ scores than students without, thought it's not entirely clear to me if that's attributed to the ADHD or just chance, and also discusses the impact of stimulant medication on their IQ scores. The relationship between intelligence and ADHD, to my knowledge, has not really been established, though it stands to reason that ADHD symptoms would interfere with IQ testing. It's not clear to me if the study is looking at these scores as directly showing reduction in symptoms or showing improved performance on tests which may be attributable to reduced interference by the symptoms.

Second, the conclusion advising starting medication at a young age is contrary to the 'common wisdom' that they're a last resort.

I'd be interested in other's thoughts on the study itself and its implications.

12-05-13, 06:43 PM
From what I've read as well as my personal experience, testing is not all that
accurate for kids with ADHD. The distraction may influence test scores, as well
as rushing to answer questions (impulsivity) without reading them very well.

12-08-13, 03:43 AM
I read the longer version but will have to admit the late hour and the waning of my own ADHD meds effectiveness has greatly diminished my ability to sit long enough to verbalize my thoughts accurately but the first thing I noticed was the lack of "blinding" Based upon my dyslexic ADHD scanning it would appear as if those giving the test were aware of the presence or absence of previous diagnosis, medical treatment so clinical bias may be a factor.

It is an extremely small sample size . . .

According to the longer version they came to the conclusion that the med helped apart from the ADHD symptom control because their medication had been with held a week prior to the testing - which begs the question of medication effectiveness over all as opposed to proving it is effective if given at a younger age.

The younger age conclusion was derived because the most improvement had been seen in the younger participants with ADHD - Ehhhhh maybe younger children matured at a faster pace which is sort of natural

Another weakness I saw in this study is the conclusion were based solely on how well the children scored on some test clinical evaluation out side of administering some psychological test were not mentioned at all. There is no mentioning regarding their life or the experience of living, socialize, ect whether or not any difference were observed or whether or not any of the areas of life outside of testing taking showed any improvement .