PhD forsvar: Bart Cooreman, Institut for Psykologi

Kandidat

Bart Cooreman

Titel

"Inter-Individual Differences in Visual Attention: A Perspective Toward an Improved Diagnosis of ADHD".

Det vil være muligt før forsvaret at gennemlæse en kopi af afhandlingen på Biblioteket ved det Samfundsvidenskabelige Fakultet, Gothersgade 140, Auditorium 1, 1353 København K

Tid og sted

17. januar 2019, kl 14.00.

Forsvaret afholdes på Københavns Universitet, Biblioteket ved det Samfundsvidenskabelige Fakultet, Gothersgade 140, Auditorium 1, 1353 København K.

Af hensyn til kandidaten lukkes dørene præcis.

Bedømmelsesudvalg

  • Professor Victoria Southgate, Department of Psychology, University of Copenhagen, Denmark (chairperson)
  • Dr. Thomas Töllner, Ludwig-Maximilians-University Munich, Germany
  • Dr. Magdalena Chechlacz, University of Birmingham, United Kingdom

Abstract

Attention Deficit Hyperactivity Disorder (ADHD) is a very common, but also a very ‘heterogeneous’ disorder. The disorder, as described in the DSM-5, is characterized by symptoms of inattention and/or hyperactivity (impulsivity), however, in some patients the inattention problems are dominant (Subtype 1), in other patients the hyperactivity (impulsivity) problems are dominant (Subtype 2), and yet another group of patients has a combined presentation (Subtype 3). The presentation of ADHD further varies in severity (ranging from mild to severe), in prognosis (some children with ADHD ‘outgrow’ the disorders, while other children develop a persistent form of ADHD in adulthood), and in terms of comorbidities (the majority of patients with ADHD suffer from comorbid disorders). Due to this ‘heterogeneity’, even today, it remains a challenge to correctly diagnose ADHD.

This PhD-thesis represents an attempt to help improve the diagnosis of ADHD, which differs from earlier attempts in at least two important ways. Firstly, we started from the assumption that ADHD is ‘normal’ (rather than abnormal); in the same way as extremely low (IQ < 60) or extremely high intelligence scores (IQ > 140) are also part of a ‘normal’ distribution of intelligence scores. A typical approach in the study of ADHD is to compare a group of ADHD-patients to a control group, thereby hoping to reveal how the group of ADHD-patients is ‘different’ from the control group (‘abnormality’). However, we chose to focus on a different question: what is normal? More specifically, what is the normal inter-individual variability that exists in, for instance, attention processes (the processes that are supposedly impaired in ADHD)? Secondly, we decided to focus on inter-individual differences in ‘visual’ attention (the attention processes involved in the processing of visual information), in particular, the role of the visual cortex herein – and also this is an atypical choice, as patients with ADHD are not usually thought of as having ‘visual’ problems. And yet, reviews and meta-analyses in ADHD have repeatedly also reported abnormalities in the visual system. 

In the PhD-thesis, we present a detailed study of ‘normal’ inter-individual variability in visual attention, using a mathematical modelling approach (based on the Theory of Visual Attention, TVA) in combination with electroencephalography (EEG). We report a series of exciting results, linking each of the parameters of this model (i.e., attention processes) to observable markers in EEG –and we explain these results as part of an ambitious new theory on visual attention. The implications of this new theory for the diagnosis of ADHD we present with the necessary caution (as the current PhD-project did not yet allow for testing the framework in ADHD patients), but it includes, among others, a re-interpretation of ambiguous previous findings reported in earlier TVA-based studies of ADHD. These studies had reported reduced processing speeds (parameter C) in children with ADHD, but reduced VSTM capacities (parameter K) in adults with ADHD; we argue that these findings are consistent with the hypothesis of a delayed neurodevelopmental maturation of the brain.