Abstract

I will present our recent meta-analyses on structural, functional and biochemical brain abnormalities in ADHD patients, evidence for specificity of these abnormalities relative to other child psychiatric disorders, effects of medications on these brain abnormalities, and non-pharmacological brain-based neuro-therapy in the form of fMRI neurofeedback.
Our meta-analysis of cross-sectional structural MRI studies shows that medication-naïve ADHD children have most consistent abnormalities in the basal ganglia and insula, which parallels our meta-analysis of positron emission tomography (PET) studies showing consistently abnormal striatal dopamine transporter levels. Our meta-analyses of functional MRI studies show cognitive domain-specific abnormalities in dissociated fronto-striatal and fronto-cerebellar networks mediating inhibition, attention and timing functions as well as problems to deactivate the default mode network, both together associated with impaired performance. Disorder-specificity of brain abnormalities will be elucidated by several meta-analyses comparing brain structure and function between patients with ADHD and patients with OCD and with autism. Our meta-analysis of acute stimulant effects on the function of the ADHD brain shows most prominent upregulation effects in right inferior frontal cortex, insula and striatum. Long-term stimulant medication treatment appears to be associated with more normal brain structure and function but with abnormal dopaminergic neurochemistry in the form of upregulation of striatal dopamine transporter levels. Little is known on Atomoxetine effects, but our direct comparisons to Methylphenidate show similar acute inferior frontal upregulation and normalisation effects. Clinical translation of neuroimaging findings in ADHD is only just emerging in the form of non-pharmacological neuro-therapy. An exciting new avenue is real-time fMRI-Neurofeedback in ADHD of areas that have been found to be dysfunctional.  A proof of concept study will be presented at the conference.

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