Growing research has linked diabetes, exposure to air pollution, and alcohol as the top three modifiable contributors to the development of dementia.
Diabetes and Dementia
People with diabetes have about 60% increased risk of developing dementia compared to those without diabetes.
There are reasons that diabetes may affect dementia risk:
Some of the changes that occur in Alzheimer's disease are similar to those in diabetes. In both, nerve cells in the brain may become resistant to the effect of insulin. This may lead to the build-up of amyloid and tau proteins in the brain.
This relationship is so strong that some have called Alzheimer's “diabetes of the brain” or “type 3 diabetes (T3D)
Air Pollution and Dementia
More than 57 million people worldwide are currently living with dementia, and estimates suggest that number will increase to 153 million by 2050. Up to 40% of these cases are thought to be linked to potentially modifiable risk factors, such as exposure to air pollutants.
Exposure to a type of air pollution called fine particulate matter, or PM, has been identified as a potential risk factor for dementia.
An NIH-funded study published on August 14, 2023, in JAMA Internal Medicine led by Drs. Boya Zhang and Sara Adar from the University of Michigan examined the links between different types of PM air pollution and dementia. They looked at data from more than 27,000 adults aged 50 and older between 1992 and 2016.
As part of the study, participants underwent cognitive testing every two years or had caretakers report on their memory and cognitive function. The mean period of follow-up was 10.2 years. The average age of participants was 60.
The researchers estimated pollution exposures for the participants using models that included real-time pollution measurements and aspects of their homes like geography, land use, and local emissions sources.
The team found that 4,105 of the people studied approximately 15% developed dementia during the follow-up period.
Overall, higher PM exposure was linked to an increased risk of dementia. The team also examined nine specific sources of PM agriculture, road traffic, nonroad traffic, burning coal for energy, burning coal for industry, other energy production, other industry, wildfires, and windblown dust. After consideration of all sources from agriculture and wildfires were specifically associated with an increased risk of dementia.
The researchers estimated that, if PM exposure truly is a cause of cognitive decline and dementia, as many as 188,000 cases of dementia per year might be due to PM.
Alcohol and Dementia
Drinking alcohol is linked to reduced volume of the brain's white matter, which helps to transmit signals between different brain regions. This can lead to issues with the way the brain functions. Alcohol consumption above recommended limits (of 14 units per week) over a long period of time may shrink the parts of the brain involved in memory. Drinking more than 28 units per week can lead to a sharper decline in thinking skills as people get older.
Long-term heavy drinking can also result in a lack of vitamin B1 (thiamine) and Wernicke-Korsakoff syndrome which affects short-term memory.
When it comes to dementia, certain risk factors, such as aging and genetics, can't be changed. But other risk factors as discussed in this article (diabetes, air pollution and alcohol consumption) are modifiable, and knowing what they are can help you take steps to minimize their impact and protect your brain.
The results suggest that certain lifestyle changes could potentially help protect the brain from these risk factors. People can cut back on alcohol consumption, follow a plant-predominant diet/Mediterranean diet and exercise to prevent or reverse diabetes, and try to avoid situations where heavy air pollution is present.
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