Adherence to the Planetary Health or Mediterranean Diets and risk of dementia in the Moli-sani Study

Background

Dementia is a major public health challenge in ageing populations, with substantial healthcare and economic burden. Dietary factors are recognised as modifiable determinants of cognitive health. The Planetary Health Diet (PHD), introduced by the EAT-Lancet Commission, promotes both human and environmental health, yet evidence on its association with dementia risk remains limited, particularly in Mediterranean populations. This study examined adherence to six PHD indices, the Mediterranean Diet (MD) and dementia risk.

Methods

We analysed 17,993 men and women from the Moli-sani Study, apparently free from dementia at baseline. PHD adherence was assessed using six scores, while MD adherence using the Mediterranean Diet Score (MDS). Association with dementia was examined using Cox proportional models, reporting hazard ratios (HRs) and 95% confidence intervals (CIs) across adherence quartiles, adjusting for risk factors.

Results

Over a median follow-up of 15 years, 442 dementia cases were identified. Correlations between the PHD indices and the MDS were weak–moderate (r = 0.16–0.56). PHD adherence was not associated with dementia risk across any score (HRs highest vs lowest adherence:0.87–1.12), with no consistent patterns across age groups. Higher MD adherence was not associated with dementia risk in the overall population (HR = 0.90; 95%CI: 0.70–1.17), but was inversely associated among participants aged ≥65 years (HR = 0.66; 95%CI: 0.48–0.92).

Conclusions

In this Mediterranean cohort, adherence to the PHD was not associated with dementia risk, whereas MD adherence was linked to a lower risk in older adults. This age-specific association may reflect increased susceptibility to MD influence later life, when underlying neurodegenerative processes are more advanced. A traditional MD pattern, as a real-world dietary model, in contrast with the more theoretical construct of the PHD, may offer cognitive advantages beyond those of a merely sustainable dietary model.

Key messages

• Adherence to the Mediterranean Diet, but not to a Planetary Health Diet, was associated with a lower risk of dementia in older adults, supporting its role in promoting cognitive health.

• These findings suggest that traditional dietary patterns may provide cognitive benefits beyond those offered by newer sustainable diet models like the Planetary Health Diet.