The prospect of dementia is one of the more feared ailments we face. It is a hard thing to endure as its direct victim, or as one of the relatives who has to look after them and watch a loved one disappear.
I am working on a book on healthy and unhealthy lifestyles across the world’s countries and dementia is one of the conditions impacting variations in life expectancy. I had a closer look at where dementia is common or rare across the globe.
Now the death rate due to one cause depends to some extent on what else influences death rates. So, I controlled for a long list of things that did, like medical spending, infectious disease rates, cancer fatality rates, pollution, smoking, and cardiovascular and diabetes-related deaths.
Dementia rates still varied widely after all those controls. The top 10 dementia rates in order were Finland, Libya, Turkey, Lebanon, El Salvador, Paraguay, Belize, Yemen, China and Equatorial Guinea. The bottom 10 dementia rates in order were Uzbekistan, Philippines, Greece, Mauritius, Singapore, Kuwait, Pakistan, Bangladesh, North Macedonia and Romania.
Parts of Scandinavia like Finland, Sweden and Iceland have high rates that their high frequency of a high-risk gene could explain. Alzheimer’s disease is one form of dementia. The proximal cause is protein tangles around the neurones. Vascular problems in the brain cause other forms of dementia. The Epo E4 gene variant increases risk of protein tangles substantially.
However, Norway and Denmark have lower rates in spite of sharing that genetic risk.
The UK, Ireland and the Netherlands round out that high-risk region of Europe, along with Albania and Slovakia. Adding to the three countries from the Balkans in the lowest 10 are Slovenia, Serbia, Croatia and Moldova. Another low-risk European area is the Baltic state of Estonia, Latvia and Lithuania down to Poland, Czechia and Austria. Portugal and Cyprus are also low risk.
The entire Middle East and North Africa region is affected badly. Also close to the top 10 were Jordan, Morocco, Qatar, Saudi Arabia, Tunisia, Egypt, Iran and Syria. Three notable exceptions are Kuwait, Iraq and Israel. This region does not carry a high genetic risk so there must be some environmental or lifestyle cause.
Low risk
In Asia the entire Subcontinent region from Pakistan to Bangladesh is low risk. In central Asia, Afghanistan and Kazakhstan are high risk but Uzbekistan and Kyrgyzstan are low risk. Myanmar to the east of the Subcontinent is high risk, as are its Southeast Asian neighbours Thailand, Cambodia, China and Mongolia. The rot runs further south and east into Malaysia, Indonesia, Timor-Leste and Brunei. Singapore is the lone low-risk country in the area. Further east, Japan, South Korea and the Philippines are low risk. Out in the Pacific, Fiji, half Subcontinental Indian, is a low-risk country.
Sub-Saharan Africa is known to harbour the high-risk gene for dementia but there are many areas that are low risk.
There is a group of them in East Africa – Chad, CAR, Ethiopia, Eritrea and South Sudan. Two East African Islands – Madagascar and Mauritius (also largely Indian) – join them. A southern group of countries – South Africa, Zimbabwe and Mozambique – have high rates of dementia. There are a few more isolated high- and low-rate countries. Interestingly, Chad and CAR have very high rates of infection-related deaths which will become relevant later in this article.
There is a concentrated region in Central America with high rates. In addition to the two in the top 10, Nicaragua, Honduras and Barbados also have high rates of dementia. In South America, Peru and Uruguay join Paraguay as high-risk countries. South America does have several low-risk countries – Argentina, Brazil and Venezuela in the east and Ecuador in the west.
One thing I found during my statistical investigation is that the rate of infectious-disease deaths is positively related to dementia death rates across countries. I would have expected death rates from other causes to be negatively related because they compete to kill people after all. This is indeed the case with many cancers. One implication is that anything that prevents serious infections will also reduce dementia rates.
Vaccines aim at preventing infections, so possibly they have preventing dementia as a side effect?
Large effect sizes
It turns out they could. A number of recent studies link vaccines against shingles, pneumonia, tetanus/pertussis and influenza to reductions in Alzheimer (one form of dementia) rates of between 17 and 30%. Those are large effect sizes. With influenza the results show that the more shots the better – for example, three and six shots per year reduced Alzheimer’s by 20 and 40% respectively over an eight-year period. Also true is that higher-dose versions of the flu vaccines have an even better effect.
The polio vaccine should do nothing for overall survival in the absence of polio. Yet it does. A study in Guinea-Bissau showed that a single dose administered to babies massively increased the chances of the baby surviving other diseases. In turns out that vaccines also reduce heart disease. For example, the shingles vaccine is associated with a 44% reduction in heart-related events, and a 66% reduction in all-cause mortality.
The chances are that all vaccines could reduce the odds of dementia plus reduce all-cause mortality in the elderly as well as the young. As an aside, the Covid vaccine(s) is controversial (I think so too) but so far investigation is incomplete with respect to dementia, or any other disease.
Effect seems stronger
I am curious about the effect of vaccines on other forms of dementia. If they reduce heart disease (and the effect seems stronger than for Alzheimer’s disease) they could reduce every form of dementia. It goes without saying that a healthy lifestyle – healthy diet, exercise, not smoking, and so on – also reduces dementia.
It does however seem clear that vaccines (and access to modern medicine in general) should be part of a healthy lifestyle. AI, medicine and health research have shown some promising new possibilities. Maybe my country findings will identify other hints. I look forward to the future. I also await the anti-vaxx onslaught to this article.
[Image: Ian Talmacs on Unsplash]
The views of the writer are not necessarily the views of the Daily Friend or the IRR.
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