To Örebro University

Knowledge about comorbidities is important since they often can affect the diagnoses, treatment and outcome of a patient. Moreover, it may provide an insight to biological underpinnings contributing to the association. Generalised joint hypermobility (GJH) has recently been suggested to be a common, yet unrecognized, comorbidity amongst individuals with NDDs. In the present thesis we aimed to evaluate the relationships between GJH and ADHD and GJH and ASD across the full clinical and non-clinical spectra. Moreover, we aimed to make available a simple screening tool for GJH for Swedish speakers.

In study I we translated the five-part questionnaire on hypermobility (5PQ) into Swedish and tested psychometric properties in a non-clinical adult population (n=315). The Swedish 5PQ showed good psychometric properties in the general adult population with a sensitivity of 91%, a specificity of 75%, and an AUC of 0.87. Thus, it is a promising measure for GJH screening in adults. 

In studies II and III we measured GJH in large cohorts of adults with ADHD (n=431), ASD (n=199) and general population controls (n=419). We evaluated the associations between GJH and ADHD and GJH and ASD by using logistic regression models, while adjusting for age, sex and ethnicity. GJH was associated with ADHD and ASD with adjusted odds ratios of 4.7 and 3.1, respectively.

In study IV a large cohort of adults from the general population (n=887) completed a survey form comprising the 5PQ and questions regarding symptoms and traits of ADHD, ASD and motor impairment. Responses were compared between GJH and non-GJH individuals. We found that sub-syndromal neurodevelopmental symptoms were not affected by GJH. Thus, the association between GJH and NDDs appears to be limited to clinical populations. However, the hypothesis needs to be tested with a physical assessment of GJH before any firm conclusions can be drawn.