Adherence to four dietary indices and the risk of all-cause and cause-specific dementia: Findings from the UK Biobank study.

Aims: Despite several modifiable risk factors for dementia being identified, diet is often excluded from consideration due to insufficient evidence. Although various healthy dietary indices have been associated with improved health outcomes, their link to dementia risk remains unclear. This study investigates the association between four dietary indices and dementia risk among UK Biobank participants.

Materials and methods: This study utilized data from the UK Biobank cohort. Dietary intake was self-reported using repeated 24-h recalls (up to five occasions), averaged for analysis. Adherence to a healthy diet was assessed using four dietary indices: the Recommended Food Score (RFS), Healthy Diet Indicator (HDI), Mediterranean Diet Score (MDS) and the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) score. The primary outcome was incident all-cause dementia, Alzheimer disease, vascular dementia, and non-vascular dementia extracted from hospital and primary care records using ICD-10 codes. Censored Cox proportional hazards models were used to estimate the risk of developing dementia and reported as hazard ratios (HRs) with their 95% confidence interval (CI). Analyses were adjusted for age, sex, education and various lifestyle and health-related factors.

Results: The analysis included 121 521 participants (mean age: 55.7 years; 53.5% women), followed for a median of 10.9 years. During follow-up, 621 participants developed dementia. Compared with individuals with the lowest dietary adherence (Quartile 1), those in the highest adherence group (Quartile 4) showed a lower risk of all-cause dementia for MDS (HR: 0.53; 95% CI: 0.45-0.63), MIND (HR: 0.61; 95% CI: 0.48-0.78), and RFS (HR: 0.66; 95% CI: 0.53-0.85). Similar associations were observed for Alzheimer disease and MDS (HR: 0.55; 95% CI: 0.46-0.67), RFS (HR: 0.61; 95% CI: 0.47-0.80), and MIND (HR: 0.66; 95% CI: 0.51-0.87). For vascular dementia, only MDS (HR: 0.46; 95% CI: 0.31-0.68) and MIND (HR: 0.68; 95% CI: 0.40-0.97) showed a lower risk. These associations remained in a 5-year landmark analysis. No associations were observed for HDI with any dementia outcome. Our findings indicate that higher adherence to specific dietary patterns, particularly the Mediterranean, RFS and MIND diet, is associated with a lower risk of dementia.

Conclusions: The Mediterranean Diet demonstrated the strongest association. These results highlight the potential of healthy dietary patterns to improve brain health in older adults.