Dementia prevention is a global public health priority due to the high social cost of the condition. The incidence of dementia can be reduced by identifying and targeting modifiable risk factors through individualized or public health interventions. One such risk factor is diet, which can be prescribed to prevent and reduce the risk of dementia. Studies have reported that healthy dietary patterns, such as the Mediterranean diet (MedDiet), are an important strategy for reducing the risk of dementia. Recent reviews have shown that higher adherence to the MedDiet is associated with reduced cognitive decline. However, further research is needed, as most previous studies have been conducted in small cohorts with a limited number of dementia cases.
A healthy diet can also reduce your individual genetic risk of dementia. However, previous studies analyzing gene–diet interactions are limited and their results are inconsistent. Polygenic risk scores are important for predicting all-cause dementia and can be used to explore gene-diet interactions in depth.
A new study in the journal BMC Medicine aimed to analyze the association between the incidence of dementia and adherence to the MedDiet, as well as to evaluate the interaction between genetic risk and diet for dementia.
Study: Following a Mediterranean diet is associated with a reduced risk of dementia independent of genetic predisposition: results from the UK Biobank Prospective Cohort Study. Image credit: Marian Veyo / Shutterstock
About studying
The study involved recruitment of participants who were enrolled in the UK Biobank study and were over 60 years of age, who self-identified as British, Irish or other white, and who had accurate genetic and dietary data. Dietary assessment was done using the Oxford WebQ, a web-based dietary assessment tool. MedDiet adherence was quantified using the MedDiet PYRAMID score and the MedDiet Adherence Screener (MEDAS) score. The MEDAS is a 14-point score widely used in observational studies and trials, and the PYRAMID score is a 15-point score widely used in epidemiological studies.
Polygenic risk scores were used to estimate the genetic risk of dementia. All-cause dementia cases were confirmed using hospital inpatient records and death registries. The International Classification of Diseases (ICD) coding system was used to record diagnoses. Sensitivity analyzes were performed to assess the robustness of the association between dementia incidence and MedDiet adherence.
Research results
Results showed that 882 cases of common cause dementia were included in the study. Participants with higher MedDiet adherence on the MEDAS continuous score were predominantly female, had a BMI in the healthy range, were more physically active, and reported having a higher level of education. The mean MEDAS continuous score was 6.1±1.7, and the PYRAMID score was 7.5±1.8.
Higher MedDiet adherence has been reported to be associated with a 4.2 to 6.9 percent reduction in dementia risk for MEDAS continuous and PYRAMID scores. In addition, polygenic risk has been reported to be associated with a higher risk of dementia. The results of the sensitivity analysis also confirmed that higher adherence to the MedDiet was associated with reduced dementia.
Therefore, the current study found that higher adherence to the MedDiet was associated with a lower risk of dementia. However, evidence for an interaction with genetic risk has been equivocal. This study highlights the importance of dietary intervention in developing strategies to prevent dementia in the future regardless of genetic predisposition.
Restrictions
The first limitation of the study is that its observational design precludes causal inferences. Second, low MedDiet adherence may have consequences and does not cause dementia. Third, calculated MedDiet scores may not fully reflect a participant’s usual dietary intake. Fourth, the number of dementia cases was obtained only from hospital records and death registries, which may have missed a few cases. Finally, UK biobank participants were of higher socioeconomic status and healthier compared to the UK general population.