Thesis defense Francesca Waddington (Donders series 544)

19 April 2022

Promotors: Prof. dr. B. Franke, Prof. dr. J.K. Buitelaar, Prof. dr. N.J. Lambregts-Rommelse
Co-promotor: Dr. N. Roth Mota

Understanding the heterogeneity and comorbidity of ASD and ADHD. A study of emotion recognition from genes to behaviour.

ASD and ADHD are frequently comorbid disorders and there is evidence that both disorders experience deficits in social cognition, particularly emotion recognition. Though there are features of ASD in ADHD and vice versa, the heterogeneous nature of these disorders at different levels means there is significant variation in the presentation of cognitive and behavioural symptoms across ASD and ADHD populations. Consequently, it is difficult to determine which deficits correspond to which causal pathway. Further investigation into the mechanisms underlying emotion recognition deficits may further our understanding of the aetiology and comorbidity of these neurodevelopmental disorders. Empirically identifying groups of individuals that are more homogeneous in their characteristics is a potentially useful approach to reducing heterogeneity. By systematically studying emotion recognition deficits in pure and comorbid ASD and ADHD, through the analysis of cognitive, genetics and brain imaging data, this thesis aimed to ascertain the extent of similarities in the neuropsychological, neurobiological and genetic mechanisms of these disorders. It also aimed to investigate if heterogeneity observed in these disorders can be reduced through establishing empirically defined homogeneous groups at the cognitive level. In this thesis, subgroups that were homogeneous in their emotion recognition abilities were identified. Individuals within each subgroup were hypothesised to be more homogenous in aetiology. This enabled the study of the relationships between these groups and with pure and comorbid ASD and ADHD. From this thesis an initial model has been developed, which proposes a pathway of the development of emotion recognition abilities. Clinical implications for both assessing emotion recognition abilities to discriminate between disorders, and interventions to improve emotion recognition difficulties were identified from this research.