A population-based study in Australia has found that the quality of your neighborhood can be linked to the risk of developing dementia later in life.

The research was based on the health data of 4,656 individuals from various states and regions between 2016 and 2020, as part of a larger study called the Healthy Brain Project. These participants were between the ages of 40 and 70, and none of them had been formally diagnosed with dementia.

Breaking down the results, the authors found those who lived in wealthier neighborhoods scored significantly higher on memory tests and lower on dementia risk tests than those who lived in disadvantaged areas.

The differences were especially large among older adults and individuals with higher dementia scores.

"Together, these data suggest that persons in more disadvantaged neighborhoods generally have higher dementia risk scores and subtle differences in memory, even in midlife," the authors conclude.

The findings are supported by recent research in the United States, which has also found a higher incidence of Alzheimer's disease among disadvantaged neighborhoods.

Interestingly, however, other studies in the United Kingdom have only found a higher risk of dementia among individuals with a lower personal socioeconomic status, not among neighborhoods.

Further research is needed to tease apart the various psychological, social and environmental factors that could be impacting these results. That way, public health experts can try to tackle the problem with the greatest efficiency.

Chronic exposure to air pollution in China and Mexico City, for instance, has recently been tied to cognitive decline, even in young people. Air pollution also tends to be worse in disadvantaged neighborhoods, which means this could be part of what's driving memory problems in lower socioeconomic groups.

Diet is another factor that could be at play. The Mediterranean diet, for instance, shows potential benefits for cognitive function as we age, but healthy foods like vegetables, berries, nuts, olive oil, and fish are typically more expensive, and adherence to this diet is generally associated with a higher socioeconomic status.

Access to green spaces, which also tend to be few and far between in disadvantaged neighborhoods, may be another factor impacting cognitive health among older adults. The same goes for access to healthcare and educational institutions like schools and libraries.

The researchers suggest that up to 40 percent of dementia cases are preventable, so if experts can figure out what risk factors might mitigate cognitive decline, we could potentially protect a large chunk of the aging population from this common group of conditions.

"With healthy lifestyle habits a key factor in reducing or delaying your risk of developing dementia, it is important for everyone to have access to local facilities such as gyms and public pools, green spaces and health care, but unfortunately that is not always the case," says neurologist Matthew Pase from Monash University in Melbourne.

"More research is needed to better understand the barriers for people so that informed solutions can be delivered at a community level to address the inequalities."

The study was published in JAMA Network Open.