Dementia in Australia

Disease burden due to risk factors is known as the attributable burden. It is measured as the number of healthy years of life lost that could have been avoided if exposure to the risk factor had been reduced or completely avoided. For more information on the complete list of established risk factors for dementia refer to What puts someone at risk of developing dementia?.

The Australian Burden of Disease Study (ABDS) 2024 estimated the dementia burden attributable to 6 modifiable risk factors, including:

• tobacco use
• overweight and obesity
• physical inactivity
• high blood pressure in midlife (35–64 years)
• high blood plasma glucose
• impaired kidney function.

43% of the dementia burden was attributable to 6 risk factors

Overall, 43% of the dementia burden in 2024 was attributable to the 6 risk factors combined, equivalent to 112,000 DALY (AIHW 2024). This estimate accounts for the complex pathways and interactions between risk factors, such as the relationship between physical inactivity, overweight and obesity, and high blood pressure in midlife. However, this work does not incorporate the impact of age as a separate risk factor for dementia. Age is the main risk factor for dementia but because it is not a modifiable risk factor, it is not included in this report.

Overweight and obesity is the leading risk factor for dementia

When looking at the independent effect of each risk factor on the total burden due to dementia (Figure 4.5):

• 20% was attributable to overweight and obesity (52,700 DALY)
• 11% was attributable to physical inactivity (29,600 DALY)
• 8.5% was attributable to impaired kidney function (22,400 DALY)
• 7.1% was attributable to high blood plasma glucose (18,700 DALY)
• 3.1% was attributable to high blood pressure in midlife (8,200 DALY )
• 2.0% was attributable to tobacco use (5,200 DALY).

While there was little difference in the proportion of dementia burden attributable to the 6 risk factors between men and women, the number of attributable DALY was often lower in men compared with women. This is due to women overall experiencing a greater amount of burden due to dementia than men.

The proportion of dementia burden attributable to each risk factor has changed between 2011 and 2024:

• the proportion due to high blood pressure in mid-life, physical inactivity and tobacco use has decreased,
• the proportion due to overweight and obesity and high blood plasma glucose has increased
• the proportion due to impaired kidney function has remained stable.

Figure 4.5: Dementia burden in Australia attributable to specific risk factors in 2011, 2015 and 2018, and 2024, by sex: percentage of DALY, YLL and YLD

How do risk factors impact dementia burden by age?

The amount of dementia burden attributable to each risk factor varied by age. This is due to age differences in both exposure to the risk factor, as well as the burden of dementia by age. The attributable dementia burden was estimated in all ages, except for high blood pressure in midlife, which was estimated for burden due to dementia in people aged 65 and over.

The dementia burden attributable to each risk factor was greatest in people aged 65–84 (Figure 4.6) and differed between men and women.

• For most age groups, women had a higher total dementia burden attributable to overweight and obesity, physical inactivity and impaired kidney function compared with men.
• Men aged under 85 typically had a higher total dementia burden attributable to high blood plasma glucose, high blood pressure and tobacco use compared with women.
• These patterns were generally seen throughout 2011 to 2024.

Figure 4.6: Dementia burden attributable to specific risk factors in 2011, 2015, 2018, and 2024, by age and sex: YLL, YLD and DALY

How do risk factors impact dementia burden by socioeconomic area?

The Australian Burden of Disease Study 2018 provided estimates of risk factor attributable burden by socioeconomic area. The amount of dementia burden attributable to each of the 6 linked risk factors varied by socioeconomic area. Poorer health outcomes are generally observed as greater rates of burden in lower socioeconomic areas. This disparity is influenced by a complex and interrelated set of social and economic factors, including reduced access to health services, lower resource availability, lower levels of education and the influence of uptake of risky behaviours (AIHW 2021).

Taking into account the different age structures in each socioeconomic area, dementia burden attributable to the 6 risk factors combined decreased with increasing socioeconomic area, and was 1.4 times as high in the lowest socioeconomic area (3.1 DALY per 1,000 population) as in the highest area (2.2 DALY per 1,000 population) (Figure 4.7). 

The rates of dementia burden attributable to each individual risk factor were consistently higher in the lowest socioeconomic areas than in the highest socioeconomic areas. The greatest difference was seen for tobacco use (2.4 times higher in the lowest socioeconomic area) and high blood plasma glucose (2.2 times higher). In each socioeconomic area, men had higher rates of dementia burden attributable to high blood pressure in midlife and (except for the lowest socioeconomic area) tobacco use than women, and women had higher rates of dementia burden attributable to physical inactivity and impaired kidney function than men.  

Figure 4.7: Dementia burden attributable to specific risk factors in 2018, by socioeconomic group: age-standardised YLL, YLD and DALY per 1,000 people