The risk of dying from dementia is most strongly associated with suburban neighborhoods, according to new research published in JAMA Network Open. Contrary to common assumptions that densely populated cities or isolated rural areas might pose the highest risk, the study indicates that environments with moderate population density, often found in suburbs, present the greatest challenge.
Dr. Liron Sinvani, a director of research and innovation at the Northwell Institute for Healthy Aging, noted that the findings challenge the expectation that pollution and overcrowding in cities or lack of social interaction in remote areas would be the primary drivers of dementia mortality. Instead, the study identified a population density of 20 to 40 people per hectare (approximately 5,000 to 10,000 people per square mile) as being linked to the highest dementia mortality rates. This density often characterizes car-centric urban areas and some outer suburban regions.
Researchers found that both highly dense cities and remote rural areas showed weaker associations with dementia mortality. Sinvani explained that dense cities often provide better access to essential services like healthcare facilities, pharmacies, and public transportation, while rural areas can offer cleaner air and greater opportunities for physical activity through nature and outdoor engagement. These factors are considered beneficial for cognitive health.
Suburban environments, however, can fall into a "worst of both worlds" scenario, according to Sinvani. They may experience environmental downsides similar to urban areas, such as traffic-related air pollution, without the same level of walkable access to doctors and services. This reduced accessibility can lead to missed appointments, delayed diagnoses, and less consistent medical care for older adults. Furthermore, a lack of walkable routes and opportunities for outdoor activity can contribute to reduced physical activity and increased social isolation, both established risk factors for cognitive decline.
The study suggests that public health interventions could significantly reduce dementia deaths. Improving access to primary care offices within walking distance, expanding public transportation options, and creating safer walking routes could potentially save tens of thousands of lives over a decade. The researchers estimate that more than 65,000 dementia deaths could be avoided through modest improvements in service accessibility or the outdoor environment.
Sinvani highlighted that targeted investments in underserved socioeconomic communities, where these environmental and access issues may be more pronounced, could have a life-or-death impact. While individuals may not be able to alter their neighborhood's layout, Sinvani offered advice for those living in areas with limited walkability or service access. Prioritizing medical appointments and utilizing family, friends, or public transport to attend them can help. Additionally, seeking out parks or other safe outdoor spaces for physical activity can mitigate some risks. The encouraging aspect of the research, Sinvani emphasized, is that the modifiable factors identified are not fixed and can be changed, offering hope for improved cognitive aging outcomes beyond genetics or age.