Fragebögen und neuropsychologische Verfahren bei ADHS – Wege zur Verbesserung der Diagnostik?

Attention-Deficit-/Hyperactivity-Disorder (ADHD) with the core symptoms inattention, impulsivity and increased motor activity is among the most common child and adolescent psychiatric disorders worldwide, causing considerable impairment for the affected and tremendous expenses for the health care system. Crucial for a successful treatment of the disorder, is a reliable diagnosis. There is a strong demand for well-validated diagnostic instruments that are specific and sensitive for ADHD and that can also be used in international multicenter studies. Rating scale measures are among the most widely used instruments in ADHD diagnosis although it is often unclear whether they can also be used in subgroups (e.g. people with migration background) as differences in cultural background can affect psychometric properties. The first article of this dissertation project thus deals with the question of whether the Conners3ed rating scales (Conners, 2008) which are often used in clinical settings, are influenced by cultural variation(Schmidt, Reh, Hirsch, Rief, & Christiansen, 2013). We tested a large group of children and their parents with Turkish migration background living in Germany. Results showed that the factor structure we found in the data was in accordance with the factor structure reported in the American original version of the test, and that the level of parent’s acculturation did not significantly influence the symptom ratings. The different rating modalities (parent-, teacher-, self- rating) did not significantly differ in degree of symptom severity. Results support the use of Conners3ed rating scales for diagnosis of ADHD in children with Turkish migration background living in Germany. Apart from rating scale measures, diagnostic guidelines for ADHD recommend the use of neuropsychological tests. Especially since other diagnostic instruments like rating scales and structured clinical interviews leave room for a large amount of subjectivity, instruments that are more objective seem urgently necessary. So far, neuropsychological tests have not shown sufficient specificity to distinguish ADHD from other psychiatric conditions. The Quantified behavior test (QbTest; Ulberstad, 2012) is the first neuropsychological test assessing not only inattention and behavioral impulsivity but also motor activity. The second article explores the factor structure and psychometric properties of the QbTest (Reh et al., 2013). The three-factorial structure, which corresponds well with the three core symptoms of ADHD, supports the assumption that the QbTest could help to make diagnosis of ADHD more objective. Intermediate phenotypes lay on the continuum from the genetic and biological causes of the disorder (genotype) to the observable behavior (phenotype). They could help reduce the large heterogeneity on the symptom level and thereby could in the long run help to improve diagnosis in ADHD. In a pilot study, the third article deals with the question whether the three QbTest factors, which were identified in the second article, could serve as intermediate phenotypes and whether especially the motor-tracking based Hyperactivity factor could potentially present a new marker for ADHD (Reh, Schmidt, Rief, & Christiansen, submitted). A group of children with ADHD showed the highest impairment across all three QbTest factors compared to a group of non-affected siblings and a group of unrelated healthy controls. Siblings showed medium and controls showed smallest values. However significant differences between siblings and controls were only found for the Hyperactivity factor. Results provide preliminary evidence for the use of the QbTest factors as risk markers in ADHD, yet studies employing larger samples are necessary. Altogether the presented studies show that the Conners3ed rating scales are robust against influences of cultural variation and seem to be applicable in international multicenter studies on ADHD. Moreover, the results of this dissertation indicate that the QbTest provides a way of separately and objectively assessing ADHD core symptoms, and that QbTest factors, especially the Hyperactivity factor present potential risk markers for ADHD. Taken together the results presented in this dissertation could help to improve diagnostics of childhood ADHD.