To Örebro University

Attention-Deficit/Hyperactivity Disorder (ADHD) and Autism (ASD) are two neurodevelopmental conditions with early onset in the developmental period, high heritability and relatively high stability through the lifespan. The evi-dence base for these findings is considerable. Less researched, however, is the extent to which neurodevelopmental conditions are associated with func-tional and physical outcomes. The impact of ADHD/ASD on physical out-comes like height, obesity, and real-life functional outcomes such as relational instability, job shifting, and residential moves remain unclear. There is also a knowledge gap to what extent there is sex differences in these associations and if the associations are present through the life span. And lastly, a detailed un-derstanding about why these associations is present is also lacking. The overarching goal of this thesis was therefore to advance the understanding of the extent to which neurodevelopmental disorders are associated with functional and physical outcomes, and why. In study I-IV, we used data from Swedish population registers. We found that individuals with ASD and their relatives are at increased risk for obesity, and that the risk is partly familial in nature (study I). Further, our findings suggest that ADHD, rather than ADHD medication, is associated with shorter height and that the association between ADHD and shorter height is partly due to a shared familial liability (study II). We also found that both men and women (from young to older adulthood) with ADHD have a higher rate of residential moves, relational instability and job shifting (study III). Finally, we found that individuals with ADHD have an increased risk of sleeping disorders, from childhood to older adulthood (study IV).

The findings from this thesis highlight the importance of a life-span per-spective of neurodevelopmental disorders, and importantly - a focus that ex-tends beyond the core ADHD symptoms to include psychiatric and physical comorbidity as well as real-life functional outcomes. Thus, our findings also point to the need for integrated care between psychiatric and physical care and helping people with neurodevelopmental conditions to navigate across health care and social systems for their functional and physical problems.