Certain countries, notably Japan and India, have especially low rates of dementia, perhaps in part related to dietary habits.
Curcumin for instance, a compound found in turmeric (a spice ubiquitous in the cuisine of the latter country) has been shown to have anti-inflammatory and cardio-protective effects. Both of these actions may reduce dementia risk, and it may even help clear amyloid – one of the chief proteins implicated in Alzheimer’s disease – from the brain.
On a more localised level, living near a main road may increase dementia risk, as suggested by a huge Canadian study of 6.6 million people.
Now, this might be related to pollution and there is direct evidence from animal studies supporting this idea. The data is hard to interpret, however, because of potential “confounding variables” – other things that are more likely to affect people living in such conditions.
These include social disadvantage which means you are less likely to have a robust education (protective for the brain) and more likely to smoke, to drink excessively, and to have stress and other mental health issues which are harmful to the brain.
Then there is the rural-urban discrepancy.
Data from Australia suggests that living in rural and remote areas is associated with a up to five times the risk of developing dementia compared with living in a more populated area.
The same variables that are relevant to the pollution situation may also be pertinent with this geographical conundrum – those living in remote areas often share the same social disadvantage.
Substantial research into why this worrying disparity occurs is about to be conducted by the University of South Australia.
One other interesting factor that might explain the geographical lottery when it comes to dementia risk is how socially connected you are.
This is a fascinating area that is still being investigated. Being around others with whom you can socially interact certainly seems beneficial for your brain, and social isolation has been associated with increased dementia risk.
Studies have demonstrated that the blood of people who report being lonely has increased levels of inflammatory molecules, and we know that chronic inflammation has a substantial role to play in Alzheimer’s disease (and many other chronic health conditions).
This might be related to the stress of feeling lonely, though it might also be partly driven by a lack of diversity of your microbiome (your gut bugs).
Think about how our everyday social interactions – hugging, touching, kissing, even sharing public spaces like supermarkets and cafes – expose us to other people’s bugs. Though this can be a bad thing, it can also help improve the diversity of your own microbiome, and diversity means a healthy gut and lower levels of inflammation.
Social isolation means less contact with others and less potential for this healthy sharing of microbes. Another explanation for the loneliness-dementia risk connection is a lack of cognitive stimulation. We know that it is a matter of use it or lose it when it comes to brain health and function, and one of the best ways to stimulate your brain is to interact with others.
Though this might not seem obvious, the act of actively listening to someone, interpreting what they are saying, holding the information in mind and then responding is a highly cognitive task.
Loneliness for many is not easily solved, but knowing how damaging it can be should motivate us all to try and address it, whether in ourselves or those around us.
Kailas Roberts is a psychogeriatrician and author of Mind your brain The Essential Australian Guide to Dementia now available at all good bookstores and online. Visit yourbraininmind.com or