Gill Livingston, University College London, UK and colleagues have published an excellent update of studies over last three years on prevention of dementia in The Lancet.
A 2017 report from the same group reported that nine potentially preventable risk factors accounted for 35% of the “population attributable risk” for dementia: low education, physical inactivity, mid-life obesity, mid-life hypertension, diabetes, hearing loss, depression, social isolation and smoking.
Centre for Healthy Brain Ageing (CHeBA) Co-Director Professor Henry Brodaty said they have now added three new risk factors that are potentially reversible:
- traumatic brain injury which was defined as mild if it led to concussion and severe if there a skull fracture. Across all severities of TBI, the risk of dementia was 84% higher and more often occurred within the first two years of the injury. The risk for dementia was higher if the injury was severe and repeated;
- heavy alcohol use was associated with an increased risk. Low to moderate alcohol intake (up to 14 standard drinks per week) has been reported as protective by some but not all studies;
- air pollution with nitrous oxygen (NO2), fine ambient particulate matter PM2-5 from traffic exhaust and domestic wood burning, and carbon monoxide.
Overall, the 12 risk factors account for 40% of the population attributable risk for dementia, said Professor Henry Brodaty.
The good news is that attending to these risk factors can make a difference.
“We all know that physical exercise is good for our heart and our bodies and also our brains,” said Professor Brodaty.
Many people are unaware that treating blood pressure can reduce risk of Alzheimer’s as well as vascular dementia, that hearing aids appear to reduce dementia risk and that treating type 2 diabetes may be of benefit. More intensive control of diabetes confers no extra advantage.
CHeBA is currently collaborating on study led by Professor Samaras from the Garvan investigating whether metformin can reduce the risk of cognitive decline in those with high blood sugars.
Professor Brodaty explained that most of these studies come from high income countries. The authors comment that the effects of these risk factors may be even stronger in low and middle-income countries which may have special resonance for Aboriginal and Torres Strait Islander communities in Australia.
“Finally, there are more studies emerging that find reductions in incidence of new cases of dementia over recent decades.
“This may be because we are more and more educated and after our cardiovascular health better.
“The bottom line is that we can all do something to reduce our risk for developing or delay the onset of dementia,” said Professor Brodaty.