Fish consumption and dementia in older people : impacts and determinants

Background: Dementia is one of the world's biggest health problems and is a major public health challenge that is becoming more common as the aged population grows. There is no known cure for dementia, and thus more efforts have been made to investigate its risk or protective factors for prevention. Previous studies suggested that increased consumption of fish reduces the risk of cardiovascular diseases. However, it is unclear whether the consumption of fish was associated with the risk of dementia and outcomes of people with dementia. Also, few studies have specifically examined factors influencing the consumption of fish in older people, despite the world population aging. The purpose of this research project was to conduct a systematic literature review and examine the determinants and impacts of fish consumption on the incidence and mortality of dementia in older people using a convergent parallel database mixed methodological approach. Methods: This study employed a systematic literature review and a mixed method of quantitative and qualitative approaches that is based on a large cohort study dataset from China and two focus group discussions from the United Kingdom. In 2007-2009, 6071 participants aged ≥60 years were randomly selected from urban and rural communities in five-provinces, China. Using a standard interview method, participants' socio-economic status, disease risk factors and fish consumption over the past two years were documented at baseline and this was followed up until 2012. The data of the cohort were analysed in multivariate adjusted logistic regression and Cox proportional hazards regression models. In 2018, the focus group discussions that consisted of 12 older adults were conducted in the UK, and the qualitative data was analysed using thematic analysis. Results: The findings of these studies demonstrated that increased consumption of fish was associated with reduced risk of dementia and all-cause mortality among older people. The study also examined and found that large socioeconomic inequalities, and certain lifestyle, psychosocial factors and health-related conditions are significant determinants of fish consumption. The qualitative study further revealed that participants consume fish for its taste, flavour, the desire for variety of food and the nutritional and health benefit including reducing the risk of dementia and other health outcomes. Although cost, bony/scaly fish, smell and availability/accessibility of fish were highlighted as the major barriers of fish consumption. Conclusions: This research has provided evidence for preventing dementia and reducing all-cause mortality through adequate fish consumption. The findings of the study should be extended to improve public health policy, and this could form the basis for further research.