New research from The Irish Longitudinal Study on Ageing (TILDA) at Trinity College Dublin highlights a widespread prevalence of treatable risk factors for dementia among older adults in Ireland, many of which remain under-treated. The study was recently published in the international journal BMJ Open.
Dementia remains one of the leading causes of disability and dependency in older adults worldwide, and its prevalence is rising rapidly. This 12-year longitudinal study, involving over 8,000 participants, provides the most detailed national picture to date of how modifiable risk factors (behaviours or exposures that can be changed or controlled to lower the risk of developing diseases) contribute to cognitive decline in later life.
The study explores the prevalence of the 14 modifiable dementia risk factors highlighted in the 2024 Lancet Commission report on Dementia Prevention, Intervention and Care. These risk factors are lower educational attainment, hearing loss, high cholesterol, high blood pressure, physical inactivity, diabetes, social isolation, excessive alcohol consumption, air pollution, smoking, obesity, traumatic brain injury, depression, and visual loss.
TILDA researchers reveal that more than 70 per cent of adults aged 50 years and older in Ireland live with at least four modifiable risk factors for dementia, representing over half a million people nationwide. Furthermore, nearly one-in-four older adults experienced moderate or severe decline in cognitive performance over the study period.
The Lancet Commission estimates that up to 45 per cent of dementia cases are preventable through addressing modifiable risk factors. Incredibly, TILDA’s findings suggest that more than 100,000 cases of dementia could potentially have been prevented during the 12-year follow-up period. A proactive and standardised approach to identify and manage these risk factors through the development of dedicated brain health services could have a profound impact on individuals, healthcare systems, and Irish society as a whole, said the researchers.
Key findings from the study include:
- Over 70 per cent of adults aged 50 years or older in Ireland had at least four treatable risk factors for dementia.
- Over 500,000 older people in Ireland had at least four treatable risk factors for dementia at all three time points across the 12-year follow-up period. To put this in perspective, this represents nearly half of Ireland’s estimated 1.1 million community-dwelling adults aged 50 years or older, based on 2022 census data.
- Almost 225,000 people or one-quarter of the population of older people in Ireland experienced moderate or severe decline in cognitive performance during the follow-up period. Those with severe decline in cognitive performance had higher numbers of modifiable risk factors compared to those with mild/ moderate decline.
The TILDA study demonstrates under-treatment of several dementia risk factors:
- Hearing loss: Less than one-third of older people with hearing loss reported using hearing aids either some or all of the time.
- Depression: Access to psychological interventions remained notably low, with only 3 per cent reporting engagement in such therapies.
- Treatment and control of key cardiovascular risk factors including diabetes, high blood pressure and
high cholesterol were found to be particularly inadequate.
Lead author Dr Caoimhe McGarvey, Research Fellow at TILDA and Specialist Registrar in Geriatric Medicine at St James’s Hospital Dublin, commented: “This study identifies a powerful opportunity to act on dementia prevention. Many of the risk factors, such as such as hypertension, high cholesterol, physical inactivity and hearing loss, are modifiable through straightforward, cost-effective interventions. By placing renewed emphasis on brain health throughout the life course and addressing these risks systematically, we have the potential to significantly delay or even prevent the onset of dementia for many individuals.”
These findings from TILDA underscore an urgent need for national brain health strategies and the integration of dementia risk management into Ireland’s healthcare system, said the authors. Preventing or delaying dementia through modifiable risk factors could dramatically reduce healthcare costs and improve quality of life for older adults.
