1: Risk and protective factors for dementia

Risk factors are attributes or exposures that increase the likelihood of a person developing a health condition. Risk factors can be grouped into 2 broad categories: non-modifiable (meaning they cannot be modified in any way) and modifiable (meaning they can be altered or treated with changes in behaviour). Diseases and injuries can also act as risk factors.

Risk factors for dementia include:

  • non-modifiable (Chen et al. 2009, AIHW 2023):
    • advancing age
    • genes associated with dementia (for example, apolipoprotein Eɛ4)
    • family history
  • modifiable (AIHW 2023, Desmarais et al. 2020, Günak et al. 2020):
    • low levels of education in early life
    • obesity in midlife
    • high blood pressure in midlife
    • tobacco smoking
    • excessive alcohol consumption
    • physical inactivity
    • high cholesterol
    • high homocysteine
    • depression
    • social isolation
    • air pollution
    • post-traumatic stress disorder (PTSD)
  • diseases and injuries (AIHW 2023):
    • cardiovascular disease (including coronary heart disease stroke, and atrial fibrillation)
    • chronic kidney disease
    • diabetes
    • depression
    • hearing loss in midlife
    • traumatic brain injury.
    Several of these diseases are modifiable with treatment and in the case of hearing loss – the use of hearing aids.

There are several other risk factors that may be associated with an increased risk of developing dementia, but more research is needed on these. They include various lifestyle and biomedical factors (such as prolonged stress, diet, inadequate sleep, and various health conditions) and environmental risks (Anstey et al. 2019). Repeated head injuries can lead to chronic traumatic encephalopathy (CTE) which is a type of brain degeneration that is associated with the development of dementia (Alzheimer’s association). CTE can only be diagnosed after death by examining microscopic changes in the brain and is often identified in brains donated to brain banks such as the Australian Sports Brain Bank (Suter et al. 2022).

The Australian Veterans’ Brain Bank, a sister organisation to the Australian Sports Bank, commenced in 2023 to examine the effect of head injury in veterans (NSW Health 2023). The Australian Former Elite Level Athlete Brain Health Research Program is a longitudinal study that is evaluating how much modifiable risk factors may contribute to the risk of poor health outcomes (AIS 2023). CTE researchers are still learning about its risk factors, causes, symptoms, progression and prevalence. Investigating data sources that could help better understand CTE and its relationship with dementia in Australia would be an important first step to improve data in this area.

Protective factors decrease the chance of a person developing a health condition or may help slow its progression. Protective factors for dementia include higher levels of education and maintaining a socially and cognitively active lifestyle (ADI 2009; Seeher et al. 2011). Actions to address modifiable risk factors include reducing high blood pressure and high cholesterol, eating a Mediterranean style diet, ceasing smoking, limiting alcohol, ensuring sufficient physical activity, healthy sleep patterns and taking protective actions to minimise head injury (Dementia Australia 2021).

Addressing the data gap and improving data

Monitoring dementia risk and protective factors by demographics such as sex, age, geography and cultural background is crucial to understand a population’s risk profile and how this impacts the rate of dementia and trends over time. Having robust and up-to-date information on risk and protective factors is needed to inform primary prevention policies. While effective policies across the entire disease pathway are important, reducing risk and increasing protective factors can reduce, delay or prevent dementia (Alzheimer's Association 2018).

Improved data on dementia risk factors includes better data on the prevalence of risk factors, the strength of association between the risk factor and development of dementia, and research into new risk factors and how risk factors work together. Potential sources for reporting dementia risk and protective factors at a national level are listed below and further sources may emerge over time.

  • The Australian Bureau of Statistics (ABS) National Health Survey collects data on population-level health risk factors, including some risk factors for dementia (such as level of highest educational attainment, obesity, physical inactivity, hypertension, smoking, hearing loss and diabetes). National data on other risk factors such as social isolation, head injuries and genetic risk factors are lacking.
  • The ABS 2021 Census asked questions on long-term health conditions, including dementia, for the first time. The Census also includes some data relating to dementia risk factors, such as highest educational attainment and household composition (a possible indicator of social isolation).
  • The Sax Institute’s Analysis of Population Traits and Risk Factors (ADAPTOR) study links longitudinal data from over 200,000 participants from the 45 and Up Study with data on their use of prescription medications, and hospital, general practitioner (GP) and other health services. It will identify people with dementia and the risk factors that may have contributed to their dementia.
  • The Centre for Healthy Brain Ageing is leading the establishment of Dementias Platform Australia. This platform aims to facilitate data sharing between dementia researchers to enhance productivity and reusability of data from contributing studies to enable the development of new insights into ageing, ageing-related diseases and dementia risk.

Genetic testing is currently not a routine part of dementia diagnosis and is usually only performed in rare cases where there is a strong family history of younger onset dementia, to assess a person’s risk of developing dementia. This may change in the future as the understanding of the association between genes and dementia increases (Dementia Australia 2022).

Genetic tests assessing a person’s risk of developing certain types of dementia are not covered under the Medicare Benefits Schedule (MBS), but de-identified data from pathology clinics offering genetic testing could be a potential future data source (subject to relevant privacy provisions) contributing to understanding genetic risk factors and their association with dementia diagnosis, clinical pathways, and outcomes.

Proposed data improvement activities

There are 2 main activities proposed to improve available data on dementia risk and protective factors. These include activities to:

  • investigate known and emerging risk and protective factors for dementia and their impacts
  • expand dementia risk factors included in Australian Burden of Disease Study analysis.

These activities may involve single projects, or multiple projects aimed at improving data on dementia risk and protective factors. Each activity provides information on the intended outcome, priority rating, level of investment required, timeframe for completion of the activity and who is responsible for undertaking the activity.