Dementia is potentially preventable and deferrable yet remains a major cause of disability, dependency and mortality worldwide. The 2024 Lancet Commission on dementia identified 14 modifiable dementia risk factors and estimated that addressing these could reduce dementia cases by up to 45%. The aim of this study is to assess dementia risk factor prevalence in adults ≥50 years participating in a nationally representative longitudinal study on ageing, providing crucial context for the delivery of dementia prevention.

The Irish Longitudinal Study on Ageing (TILDA) is a population-based prospective cohort study, representative of community-dwelling adults ≥50 years living in Ireland.

All participants from waves 1 (2009–2010): n=8171, 3 (2014–2015): n=6615 and 6 (2021–2023): n=4318 of TILDA were analysed over a 10.93 (±0.37) years of follow-up.

70.6%, 61.1% and 54.2% of the population had ≥4 modifiable risk factors for dementia at consecutive waves, amounting to over 500 000 people with ≥4 modifiable risk factors for dementia on weighted population analysis at wave 6. 77% of those with severe decline in cognitive performance during follow-up had ≥4 risk factors at baseline. An estimated 32 480 cases of severe decline in cognitive performance during follow-up were potentially preventable if risk factors were addressed.

In a nationally representative sample of older European adults, there is a high prevalence of modifiable dementia risk factors. This highlights the need for greater attention on educating people on the concept of brain health through public health messaging as well as the development of a clinical framework focused on delivering on the opportunity of dementia prevention. Preventing and delaying dementia onset can have a significant impact on the compression of morbidity and increasing healthy lifespan in older age.