I find the results of this study especially relevant for people with ADHD Inattentive because the symptoms of the Inattentive subtype of ADHD include greater problems with attention related cognition and fewer problems with behavior.
Behavioral problems are a huge problem for adults and children with the Combined type of ADHD and only a small part of the problem for adults and children with the Inattentive type of ADHD. It is for this reason that I recommend that kids and adults with Inattentive ADHD be treated with a low dose of stimulants if it is determined that stimulants are the best treatment for them.
I have posted more about this Inattentive ADD attention vs behavior issue in a few posts but I wanted to quickly share the results of this study with you as the findings are similar to other studies that have shown that the stimulants do not work to improve academic performance though they do improve school behavior.
Journal of Child and Adolescent Psychopharmacology. 2011 Jun;21(3):245-53.
Effects of methylphenidate on intelligence and attention components in boys with attention-deficit/hyperactivity disorder.Hellwig-Brida S, Daseking M, Keller F, Petermann F, Goldbeck L.
Abstract Background: Methylphenidate (MPH) is an efficient treatment to reduce behavioral symptoms of attention-deficit/hyperactivity disorder (ADHD); however, its impact on cognitive functioning has not been sufficiently demonstrated so far. This study investigates the hypothesis that MPH improves attention-related cognitive functions. Methods: Sixty-seven medication-naive boys aged 6-13, with newly diagnosed ADHD, were tested before treatment with a neuropsychological assessment battery, including the Wechsler Intelligence Scales for Children (WISC-IV) and the Test of Attentional Performance for Children (KITAP). A follow-up assessment was performed after 8-12 weeks, with 37 participants receiving MPH treatment and 30 controls without medication. The effect of MPH on test performance was analyzed by repeated measures analyses of variance. Results: Both groups improved significantly across a broad range of psychometric measures of cognitive performance. There were no significant interaction effects of group and time on attention-related cognitive functions. Exploratory analyses revealed an effect of MPH on verbal comprehension in the WISC-IV. Conclusion: The study results do not support that MPH improves attention-related cognitive functions of boys with ADHD. The potential effect of MPH on verbal abilities deserves further research.