Verlauf von ADHS-Symptomen zwischen Kindergarten- und Schulalter: Bedeutung neurokognitiver Basisdefizite

Attention deficit hyperactivity disorder (ADHD) is a disease of the lifespan with multiple underlying developmental processes in early childhood. An internationally well-established construct on the etiology of ADHD is the multiple causal pathways model. In this, specific gene-gene and gene-environment interactions lead to alterations in central neural circuits. These neurobiological alterations can cause deficits in neurocognitive functions, which are possible precursors of the heterogenous symptoms of ADHD. In the present study it’s examined, whether preschool neurocognitive deficits of executive functions (executive inhibition control, working memory) and reward-related functions (reward-related inhibition control) predict the development of ADHD symptoms and diagnosis in elementary school. Therefore, a community-based sample of 122 preschoolers (70 boys) was assessed at age 4/5 and 8 years. Neurocognitive functions were measured by several age-appropriate tasks. ADHD symptoms were measured using the teacher version of an ADHD questionnaire and a clinical parental interview. The latter was also used to diagnose ADHD. The study results show that a deficit in reward-related inhibition control predicted ADHD symptoms and diagnosis measured by clinical parental interview, even after controlling for maternal education level, baseline ADHD symptoms and common psychiatric comorbidities. A statistical trend was found for the prediction of ADHD symptoms and diagnosis by deficits in executive inhibition control, whereas the working memory was not found to be a relevant predictor. None of the neurocognitive deficits predicted ADHD symptoms rated by teachers. To sum up, the results add empirical evidence on the theoretical assumptions of the multiple causal pathway model by identifying early deficits in executive and reward-related inhibition control as being relevant predictors of later ADHD symptoms and diagnosis. Our findings emphasize the importance of these neurocognitive deficits as potential targets for prevention. Furthermore, the results point out to the potential value of neuropsychological tests for diagnostic reasons and for clarifying differential diagnosis.