Aims: The aim of this study is to analyse the differences in the Stroop effect between cases with attention deficit hyper-activity disorder (ADHD) and controls. It also seeks to find the best model based on the third task of the colours and words test (Stroop-CW) for predicting ADHD and to analyse the validity of the Stroop-CW test for diagnosing the disorder.
Subjects and methods: The sample studied consisted of 100 cases of ADHD -according to Diagnostic and statistical manual of mental disorders (DSM-IV) criteria- and 100 controls, between 7 and 11 years of age, who were evaluated using the Stroop test. The controls were recruited at random and paired by age, sex and sociodemographic area with the cases.
Results: The cases present a mean cognitive style that is significantly less flexible (d = -1.06) and they also display a lower capacity to inhibit or control automatic responses than the controls at all ages (7 years: d = 1.67; 8 years: d = 1.02; 9 years: d = 1.32; 10 years: d = 2.04; 11 years: d = 0.89). The model of logistic regression analysis that best predicts ADHD is made up of age and Stroop-CW. The formulation derived from the model offers a sensitivity of 81% and a specificity of 72%, taking the criteria of the DSM-IV for ADHD as the reference test.
Conclusions: The Stroop-CW test presents usefulness and complementary criteria validity for the diagnosis of ADHD.