ADHD and Stroop interference from age 9 to age 41 years: a meta-analysis of developmental effects

In this meta-analysis, we investigated whether response inhibition is sensitive to attention deficit hyperactivity disorder (ADHD) status and, if so, what influence maturation has on this attentional symptom of ADHD.

We examined 25 studies that reported data on the Stroop color word test in children and adults with ADHD and in age-matched controls; average ages ranged from 9 to 41 years. We utilized a hierarchical approach to analyze the strength of the Stroop effect and whether the effect varies as a function of age. Additionally, we assessed potential differences in maturation rates based on reaction time (RT) of color and color-word conditions.

First, we found that the relationship between color-word and color RT was multiplicative, and the slope of this function (the ratio of color-word RT over color RT) was identical across age groups and ADHD status. Second, we found that although ADHD individuals were on average 1.14 times slower than age-matched controls in both the color and the color-word condition, the maturation rate was identical for both groups.

The results from this analysis indicate that the Stroop interference effect is not larger in ADHD individuals than in age-matched controls. Further, we did not find evidence for differential maturation rates for persons with ADHD and the control groups. The Stroop interference effect appears to be immune to age, regardless of ADHD status.