The first chapter is a systematic literature review examining what the evidence is for neurological and cognitive symptoms of coeliac disease and non-coeliac gluten sensitivity in adults. The second presents a piece of research investigating whether illness perceptions are moderated and mediated through self-efficacy for the gluten free diet and coping for the outcomes of psychological wellbeing and quality of life. The final chapter is a brief public dissemination document that provides an overview of this thesis.