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Keynote Lecture 8

ADHD Neuroscience: What Have We Learned from Three Decades of Research?

Edmund Sonuga-Barke PhD

University of Southampton

Our story begins in 1997. In that year Professor Russel Barkley, one of the most eminent
researchers in the field of ADHD, published one of its most influential papers. In it he argued very
persuasively that ADHD is the result of core deficits in inhibitory-based executive function. This
hypothesis has provided the inspiration for much of the ADHD neuroscience research carried out
over the last three decades. During that period we have learnt a lot. First, we have found out, just as
predicted, that many children with ADHD have deficits in domains such as planning, attentional
flexibility, inhibition and working memory and these are underpinned by deficits in executive control
networks. Second, it is now clear however, that a generalized pattern of executive deficit is present in
only a minority of patients with ADHD. In fact, it is increasingly clear that ADHD is extremely
complex and heterogeneous pathophysiologically with deficits in multiple interacting brain networks
creating profiles of cognitive and motivational impairment that differ profoundly between different
groups of patients. Finally, even for individuals where executive function deficits are present, recent
results from both developmental and treatment studies raise doubts about whether they play a core
causal role rather than being an independent complication or an exacerbating factor. In this talk, by
reviewing this data we highlight the dramatic way prior single core deficit models of ADHD has
given way to more conceptually sophisticated and biologically plausible ones that emphasize
complexity, heterogeneity and alternative views of causality.