This review looked at research on children who have both ADHD and a reading disability. The authors found 6 relevant studies published between 1995 and 2016, plus a brief look at older work. The paper does not give the children's ages or the total number of children across the studies.
Summarizing other studies, the authors report that two kinds of ADHD medication may help reading. One is a stimulant (methylphenidate) and the other is a non-stimulant (atomoxetine). The authors suggest this may happen by supporting skills such as working memory, processing speed and attention. In one study, more than half of the children had better ADHD symptoms on methylphenidate (59%). Another study found only small effects, with the stimulant speeding up color naming but not the naming of letters and numbers. Atomoxetine was linked to better decoding and spelling, but these gains were only weakly linked, or not linked at all, to changes in ADHD symptoms.
The findings conflict, though. One study found atomoxetine did not significantly change reading performance, while another found reading scores went up. Research from the 1980s and early 1990s also questioned whether stimulants helped reading. The studies used different methods, groups and measures. The authors call for more blind, randomized trials that compare medication with a dummy pill, and for reading programs that do not rely on medication.
Citing earlier work, the authors suggest treating both conditions together, pairing medication with behavioral or educational support, though they do not recommend a specific medication.
Source: Christina Gray, Emma A. Climie. Children with Attention Deficit/Hyperactivity Disorder and Reading Disability: A Review of the Efficacy of Medication Treatments. Frontiers in Psychology (2016). doi:10.3389/fpsyg.2016.00988