11 Jun ADHD and OCD Patients Differ Fundamentally in Brain Abnormalities
MedicalResearch.com Interview with:
Dr. Katya Rubia
Katya Rubia, PhD
Department of Child and Adolescent Psychiatry
Institute of Psychiatry, Psychology, and Neuroscience
King’s College London
London, England
MedicalResearch.com: What are the main findings?
Dr. Rubia: ADHD and OCD patients both suffer from poor inhibitory control and in both disorders this has been associated with structural and functional deficits in fronto-striatal networks. However, it is not clear to what extent the two disorders differ in their underlying neural substrates. This study therefore conducted a meta-analysis of all published whole brain structural and functional MRI studies of inhibitory control in both disorders.
MedicalResearch.com: What are the main findings?
Dr. Rubia: The main findings are that ADHD and OCD patients differ quite fundamentally in their structural and functional brain abnormalities. OCD patients have enlarged volume in basal ganglia and insula, while ADHD patients have reduced volumes in these regions. In fMRI, in the left hemisphere this was also observed for the left insula and putamen, which were increased in OCD and reduced in ADHD. In addition both disorders have different frontal deficits. OCD patients have deficits in rostro-dorsal medial frontal regions that are important for top-down control of affect while ADHD patients had reduced activation in lateral inferior frontal cortex, a key area of attention and cognitive control. The findings fit into the notion of fronto-striatal dysregulation in OCD where basal ganglia are overactive and poorly controlled by medial frontal regions and a delayed fronto-striatal maturation in ADHD where both lateral frontal regions and the basal ganglia/insula are smaller, and presumably less developed in structure and in function in ADHD.
MedicalResearch.com: What should readers take away from your report?
Dr. Rubia: ADHD and OCD patients both have deficits in inhibitory control, i.e. they have a similar behavioural and neuropsychological endophenotype, but the underlying neural structural and functional substrates that are associated wth this phenotype are very different.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Dr. Rubia: It would be very interesting to investigate the structural and functional deficits in patients who have comorbid ADHD + OCD as this group is not known in terms of underlying neural deficits.
It would be also important to investigate the underlying neurotransmitter abnormalities in both disorders and how they differ. There is some evidence from PET studies that dopamine is enhanced in the basal ganglia in OCD but decreased in OCD which would fit into the current structural deficit findings of enlarged basal ganglia in OCD and reduced basal ganglia in ADHD.
MedicalResearch.com: Is there anything else you would like to add?
Dr. Rubia: I would suggest that the findings have implications for treatment. Given the different activation and structure findings in the basal ganglia this would imply that treatment for ADHD and OCD should be different as they should target disorder-differential brain abnormalities. In fact, stimulant medication tends to make repetitive stereotyped behaviours worse and is not usually a medication used to treat OCD.
MedicalResearch.com: Thank you for your contribution to the MedicalResearch.com community.
Citation:
Norman LJ, Carlisi C, Lukito S, et al. Structural and Functional Brain Abnormalities in Attention-Deficit/Hyperactivity Disorder and Obsessive-Compulsive Disorder: A Comparative Meta-analysis . JAMA Psychiatry. Published online Jun[wysija_form id=”5″]e 08, 2016. doi:10.1001/jamapsychiatry.2016.0700.
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Last Updated on June 11, 2016 by Marie Benz MD FAAD