Brain Morphometry and Cognitive Outcomes in Adolescents and Adults with Complex Congenital Heart Disease

Abstract

This thesis examines long-term cognitive outcomes and brain morphometry in adolescents and adults with complex CHD. Consideration is given to the broader impact of these challenges on psychosocial outcomes, and we attempt to advance our understanding of potentially modifiable risk factors. Strategies to address the insufficiencies in current clinical resources are explored.

In Chapter 3 we demonstrate that young people with a Fontan circulation experience marked reductions in cognitive functioning in comparison to age- and sex-matched individuals with transposition of the great arteries and healthy controls. Structural brain injury was not indicative of worse cognitive outcomes. Whereas global brain volumes appear to be a key structural underpin contributing to cognitive dysfunction and are associated with lower resting oxygen saturations. Chapter 4 advances these findings and demonstrates that reduced resting and peak exercise oxygen saturations are significantly associated with worse white matter microstructural integrity, indicating that persisting hypoxaemia may be a modifiable risk factor contributing to long-term brain abnormality. In Chapter 5 we show that lower socioeconomic status is a risk factor for worse cognitive outcomes in adults with complex CHD, who may not recognise or report their cognitive challenges. Psychological distress is common though was not a strong correlate of cognitive functioning. Chapter 6 demonstrates that Cogstate may be a useful screening tool to identify individuals with CHD who are most in need of a formal evaluation.

Combined, this work adopts the biopsychosocial approach to wellness and investigates biological, psychological, and social factors that contribute to cognitive dysfunction in complex CHD. The research serves to guide future clinical practice and the development of theory driven intervention strategies to optimise long-term outcomes for those at risk.