Exploring the value of dietary intervention in the management of psychosis: a mixed method study

Psychosis is a clinical syndrome that has a large impact on individuals and their families. Current treatment is not fully efficacious. The formation and function of the brain is dependent upon nutrients, supplied through the diet. Despite this, evidence indicates that diets, particularly for those with psychosis are sub-optimal in terms of nutritional value. The aim of this PhD therefore was to explore the value of diet intervention for psychosis management, which was rooted in Pragmatism and followed an explanatory sequential mixed-methods design aligned to the Medical Research Council’s (MRC) Framework for the development and evaluation of complex healthcare interventions (Skivington et al., 2021). The first part of this PhD was the conduct of a systematic review and meta-analyses, the outcome of which was that no suitable diet intervention existed for psychosis management. The findings informed interview topic guides for two qualitative studies that sought the views of: (i) healthcare professionals (HCPs) experienced in psychosis management and (ii) patients and carers on diet intervention for psychosis management. The data were thematically analysed separately (Braun and Clarke, 2006) into four themes for each respective study. Findings from these studies were synthesised into a Pipeline Logic Model, following the principles of triangulation (Farmer et al., 2006). This provided the contextual factors and elements of programme theory required to develop and deliver a diet intervention for psychosis management. Stakeholders would value diet intervention for psychosis management, delivered by trained HCPs within NHS mental health services. The evidence-based diet intervention should be accessible to patients and should lead to the necessary dietary knowledge and skills. The principal recommendation following this PhD is to further develop a diet intervention for psychosis management with an increased stakeholder group, which should include NHS mental health service commissioners and academics responsible for HCP pre- and post-registration curricula.