What puts someone at risk of developing dementia?

There are a number of factors that can increase a person’s likelihood of developing dementia. Some risk factors can be avoided or reduced (known as ‘modifiable risk factors’) and others cannot be changed (known as ‘non-modifiable risk factors’). As there is currently no cure for dementia, minimising modifiable risks is currently the best way to prevent dementia (Livingston et al. 2020; Prince et al. 2014). Having 1 or more of these risks factors does not mean you will definitely develop dementia, rather it increases the individual chance of dementia developing.

Non-modifiable risk factors

Ageing is the main risk factor for dementia. While dementia can occur in people aged under 65, the risk of developing dementia doubles every 5 or 6 years for people aged over 65. However, it is not known whether or not this increasing risk continues at the same rate past the age of 90 due to challenges with diagnosis in this age group—more research is required (Corrada et al. 2010; Gardner et al. 2013; Slavin et al. 2013). Other non-modifiable risk factors for dementia include: a family history of the condition, and other genetic mutations or variations (namely, the apolipoprotein E (APOE) ε4 gene and Down syndrome). See Dementia among people with intellectual disabilities for more information on dementia among people with Down syndrome. 

Modifiable risk factors

Modifiable risk factors for dementia include a number of cardiovascular and lifestyle factors (often associated with other chronic diseases) as well as a number of social factors. For certain risk factors, a person’s age when exposed to that risk plays a role in their likelihood of developing dementia. For other risk factors, it does not matter when a person is exposed—the level of increased risk remains the same.

It is estimated that 40% of new cases of dementia could be avoided if the majority of the modifiable risk factors for dementia were eliminated (Livingston et al. 2020). Additionally, a 20% reduction in exposure to 7 key risk factors— diabetes, hypertension in midlife, obesity in midlife, physical inactivity, depression, smoking, and low educational attainment— could lead to a 15% reduction in the prevalence of Alzheimer’s disease by 2050 (Norton et al. 2014).

Modifiable risk factors recognised as having strong evidence for their association with increased risk of developing dementia include:

  • low levels of education in early life
  • obesity in midlife
  • hypertension in midlife
  • hearing loss in midlife
  • tobacco smoking
  • excessive alcohol consumption
  • physical inactivity
  • high cholesterol
  • high levels of homocysteine— an amino acid produced when proteins are broken down
  • atrial fibrillation
  • diabetes
  • depression
  • social isolation
  • air pollution
  • traumatic brain injury (Anstey et al. 2019; Livingston et al. 2020).

Further information on the dementia burden in Australia due to a number of modifiable risk factors is described in Dementia burden due to risk factors.

There are a number of other risk factors that may be associated with an increased risk of developing dementia. However, the evidence of association is weaker than for the risk factors listed above. 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). Further research is needed to determine if these are associated with an increased risk of dementia.

Protective factors

The World Health Organization has developed recommendations on the types of interventions that should be adopted to reduce risks associated with cognitive decline and dementia. These include a number of cognitive, behavioural, social and pharmacological interventions aimed at improving health overall and reducing exposure to known modifiable risk factors associated with dementia (WHO 2019a).

Protective factors for dementia include:

  • undertaking regular physical activity and eating a healthy, balanced diet
  • maintaining a healthy weight
  • quitting smoking and reducing alcohol intake
  • maintaining an active social life
  • keeping mentally stimulated
  • managing other health conditions, such as hypertension, hearing loss, diabetes and depression (WHO 2019b).

A person at any age can reduce their risk of developing dementia (and other health conditions) by making some or all of these lifestyle changes. As further research on risk factors for dementia is undertaken, the list of recognised risk and protective factors will be updated.  

Assess your dementia risk

Dementia Australia provides further information and a range of resources on reducing your risk of dementia.

Researchers at the Australian National University (ANU) have developed a tool to assess an individual’s exposure to risk factors associated with an increased risk of developing Alzheimer's disease in late-life (over 60 years). The ANU Alzheimer's Disease Risk Index (ANU-ADRI) provides an individualised assessment and report on Alzheimer's disease risk factor exposure.