ROESSNER, V., Banaschewski, T., Becke A., Buse, J., Wanderer, A., Buitelaar, J. K., Sergeant, J. A., Sonuga-Barke, E. J. S., Gill, M., Manor, I., Miranda, A., Mulas, F., Oades, R. D., Roeyers, H., Steinhausen, H-C., Faraone, S.V., Asherson, P., Rothenberger, A.,

Familiality of Co-existing ADHD and Tic Disorders: Evidence from a Large Sibling Study Frontiers in Psychology, 7, 1060.

.(open access)

Introduction: (i)The association of ADHD & tic disorder (TD is frequent & clinically-important. -- But very few & inconclusive attempts have been made to clarify if and how the combination of ADHD + TD runs in families.

(ii) We aimed to determine the first time in a large scale ADHD sample whether ADHD+TD increases the risk of ADHD+TD in siblings and for the first time, if this is independent of their psychopathological vulnerability in general.

Method: The study is based on the International Multi center ADHD Genetics (IMAGE) study. The present sub-sample of 2815 Ss included ADHD-index patients with co-existing TD (ADHD+TD, n=262) and without TD (ADHD-TD,n=947) as well as their 1606 full siblings (n=358 of the ADHD+TD index patients and n=1248 of the ADHD- TD index patients).

-- We assessed psychopathological symptoms in index patients and siblings by using the Strength & Difficulties Questionnaire (SDQ) and the parent and teacher Conners 'long version Rating Scales(CRS). For disorder classification the Parental Account of Childhood Symptoms (PACS-Interview) was applied in n=271children. Odds ratio with the GENMOD procedure (PROCGENMOD) was used to test if the risk for ADHD, TD, and ADHD+TD in siblings was associated with the related index patients'diagnoses. In order to get an estimate for specificity we compared the four groups for general psychopathological symptoms.


1/ Co-existing ADHD+TD in index patients increased the risk of both comorbid ADHD+TD and TD in the siblingsof these index patients.

2/ These effects did not extend to general psychopathology.

Discussion & Interpretation:

a) Co-existence of ADHD+TD may segregate in families.

b) The same holds true for TD (without ADHD).

c) Hence ,the segregation of TD (included in both groups) seems to be the determining factor, independent of further behavioral problems.

This close relationship between ADHD and TD supports the clinical approach to carefully assess ADHD in any case of TD.