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Excitatory-inhibitory balance in children with 22q11.2 deletion syndrome

Doherty, Joanne Louise 2019. Excitatory-inhibitory balance in children with 22q11.2 deletion syndrome. PhD Thesis, Cardiff University.
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Abstract

22q11.2 deletion syndrome (22q11.2DS) is a copy number variant syndrome affecting approximately 1 in 4000 live births. It has a variable phenotype in terms of its physical, cognitive and psychiatric manifestations. People with 22q11.2DS have a range of cognitive difficulties. They also have extremely high rates of psychopathology, particularly attention deficit hyperactivity disorder, autism spectrum disorder, anxiety disorders and psychotic disorders. The mechanisms underlying the risks of cognitive impairment and psychopathology are not wellunderstood. The balance between excitation and inhibition in the brain may be affected in 22q11.2DS and could underlie its cognitive and psychiatric features. In this thesis markers of excitatory-inhibitory (E-I) balance were investigated in children with 22q11.2DS (probands) and typically developing children (controls). It was hypothesised that probands would have alterations in E-I balance and that the severity of these alterations would be associated with cognitive and psychiatric features. The phenotypes of children taking part in the brain imaging study was first compared to those of children who did not participate in brain imaging to assess the representativeness of the imaging sample. Resting-state brain networks and visually-induced gamma oscillations were then investigated using magnetoencephalography (MEG) and gamma-amino-butyric acid (GABA) concentrations were investigated using magnetic resonance spectroscopy (MRS). Between-group comparisons were performed and the relationships between markers of E-I balance, psychopathology and cognitive impairment were explored using linear regression. The phenotypes of children with 22q11.2DS who participated in brain imaging were broadly similar to those who did not participate, suggesting that the imaging sample does not represent a highly-functioning subsample. Compared with controls, probands had alterations in resting-state networks in the delta, alpha and beta bands which were associated with anxiety, social communication problems and cognitive deficits. In the gamma band, there were reductions in the total induced gamma power in probands, which was similarly associated with social communication and cognitive difficulties. There were no alterations in GABA concentrations in 22q11.2DS, suggesting that further work is needed to better understand the mechanisms underlying excitatory-inhibitory imbalance in 22q11.2DS.

Item Type: Thesis (PhD)
Date Type: Completion
Status: Unpublished
Schools: Medicine
Subjects: R Medicine > R Medicine (General)
Date of First Compliant Deposit: 24 May 2019
Last Modified: 24 May 2019 11:36
URI: http://orca.cf.ac.uk/id/eprint/122836

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