Longevity Briefs: It’s Not Too Late To Lower Your Risk Of Dementia

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

The problem:

Recent evidence suggests that nearly half of dementia cases could be prevented by adopting the proper lifestyle practices at various stages of life. But what if it’s too late? We know that people who have already developed metabolic diseases (like type II diabetes) and cardiovascular diseases are significantly more likely to develop dementia in later life. Does a late change in lifestyle still prevent dementia in such people, or has too much damage already been done? This study set out to investigate .

The discovery:

Researchers looked at data from 80,000 dementia-free British adults over the age of 60, and followed them up for a median of 12.4 years. They used detailed food questionnaires given at multiple times during the study to estimate an ‘inflammatory index score’ (inflammation is thought to be a key driver of many age-related diseases, including dementia). They found that an anti-inflammatory diet had significant advantages in both people with and without cardiometabolic diseases.

In non-diseased people, consuming a pro-inflammatory diet was associated with a 21% increase in dementia risk over the course of the study compared to consuming an anti-inflammatory diet. Yet in people with at least one cardiometabolic disease, a pro-inflammatory diet was associated with a 44% increase in dementia risk compared to an anti-inflammatory diet. Not only that, but when participants with cardiometabolic diseases underwent brain MRI scans, those on an anti-inflammatory diet had significantly higher grey matter volume (grey matter loss is a key characteristic of dementia). Finally, in those participants who did go on to develop dementia, an anti-inflammatory diet was associated with a significant delay in onset.

The implications:

While the prospects for the treatment of dementia remain bleak, research continues to suggest that the prospects for prevention are not, even among older people who are already at risk. Anti-inflammatory diets are generally plant-focussed, with an abundance of fibre-rich foods and polyphenols and minimal saturated and trans-fatty acids. However, it is worth noting that the people with cardiometabolic diseases consuming anti-inflammatory diets were still significantly more at risk than the disease-free participants, even those consuming the most inflammatory diets. In other words, avoiding cardiometabolic diseases in the first place should still be a priority.

Since the researchers didn’t randomise participants to receive either a pro- or anti-inflammatory diet while keeping everything else the same, we can’t be certain that the diet was responsible for all of the observed differences. For example, people who eat less healthy diets tend to be less wealthy and have a poorer education, both significant risk factors for dementia. Studies like this one use statistical techniques in an attempt to adjust for such confounders, but these adjustments are never perfect. There’s also some potential for reverse causation, since dementia-related changes in the brain can precede diagnosis by many years, and these changes may influence food preferences and appetite.