Promoting uptake of the MIND diet to prevent cognitive decline in adults at midlife
: Employing the Behaviour Change Wheel and COM-B model

Student thesis: Doctoral Thesis


Background: The incidence of dementia is predicted to double every 20 years, with prevalence in the UK to reach 2.1 million by 2050. Modifiable risk factors such as diet in midlife have been shown to be associated with a reduced risk of dementia in later life. The aim of the research was to use the Behaviour Change Wheel and COM-B model to explore barriers and facilitators to the uptake of the MIND diet (Mediterranean-DASH Intervention for Neurodegenerative Delay) which was designed to promote brain health, and examine the effects of a dietary intervention on the cognitive function, mood and quality of life of Northern Ireland adults in midlife.
Design: The Behaviour Change Wheel (BCW) was used to guide and inform intervention development which involved the use of several methodological approaches. A systematic review was conducted to assess the effectiveness and use of psychological theory in dietary interventions that promote a whole diet. Content of the interventions were coded according to the Theory Coding Scheme. Focus groups and interviews based on the COM-B model and Theoretical Domains Framework (TDF) explored barriers and facilitators to the uptake of the MIND diet (n=25). The BCW guided the systematic selection of intervention function, behaviour change techniques and mode of delivery in designing a 12-week randomised controlled feasibility dietary intervention (n=41). Outcome measures for COM-B, cognitive function, mood, and quality of life was recorded for both the intervention and control groups. Participants were healthy males and females aged between 40-55 years old, living in Northern Ireland
Results: Nine intervention studies were included in the systematic review. Results found that dietary scores improved for at least one food group. Overall, studies reported a moderate application of the theory coding scheme, with poor reporting on fidelity. Content analysis revealed that the main perceived barriers and facilitators to the uptake of the MIND diet were; time, work environment, taste preference and convenience, improved health, planning and organisation, and access to good quality food. A repeated measures ANOVA showed that in comparison to the control group, the 12-week dietary intervention improved mood, quality of life, MIND diet score and capability, opportunity, and motivation towards MIND diet consumption.
Conclusion: Findings from this research provide insight into the personal, social, and environmental factors that participants report as barriers and facilitators to the uptake of the MIND diet. To our knowledge, this is the first study to use a theoretical framework to explore people’s attitudes towards consuming the MIND diet, and the first RCT examining the effectiveness of the MIND diet on health outcomes. The results add to the dietary and cognitive function literature and to the behaviour change literature by describing and specifying the design, content, proposed mechanism of action and implementation for a theoretically informed dietary intervention. Recommendations for enhancing the role of health professionals in promoting cognitive function at midlife in an attempt to promote functional independence and better cognitive function in later life.
Date of AwardFeb 2021
Original languageEnglish
SupervisorMaeve Kerr (Supervisor) & Liz Simpson (Supervisor)


  • Diet
  • Cognitive function
  • COM-B model
  • Behaviour Change Wheel

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