In a July 2024 article published in Nature Medicine, Oxford University scientists reported that getting vaccinated against shingles also reduces your risk of developing dementia later in life.
The UK-based cognitive scientists gathered data from the medical records of over a quarter million American senior citizens. Advanced number crunching allowed the researchers to compare the health outcomes of over 65s who got a shingles jab between 2017 and 2020. In a surprising finding, the academics noticed that on average, seniors who got the shot delayed the onset of all kinds of dementia other than frontotemporal and Lewy body dementia for as long as 164 days. Another way to put it is that people who got vaccinated got 17% longer before they were diagnosed with dementia. These differences applied equally in men and women.
Averages Can Smooth Out Big Changes
Since these results are presented as averages, it’s worth noting that large effects will skew the number. The findings are an average taken over 103,837 people who got a shingles vaccine compared to 103,837 individuals who skipped the shot. A good number of those people might never have developed dementia in either group, so the differences between the two groups could look smaller – as the extra days are spread over more people. Blockbuster Alzheimer’s drugs such as Lecanemab have similar outcomes – giving patients an average of six months longer before decline. The similar length average extension conferred by the shingles vaccine, could therefore, work out to be a lot more than 164 days in a subset of individuals. The scientists are not yet ready to explain what causes the effect or how. Some suspect that the varicella-zoster virus could precipitate dementia by damaging the neurons.
Accounting for Other Variables
This was a surprising finding, so of course, the researchers tested whether they could use other factors to explain the differences.
The statisticians checked whether people in the vaccinated group died early before they could develop dementia. They also probed whether the impact of COVID-19 could have prevented or delayed dementia diagnoses.
The researchers then considered the question of whether simply getting vaccinated against anything would be linked to a delay in dementia. Could it be that people who are proactive about getting vaccines are generally more health conscious and take better care of themselves?
Perhaps people within six years of a dementia diagnosis might not be as on top of organizing health care appointments due to early symptoms of decline?
When the researchers compared the onset of dementia in seniors who got the shingles shot to those who only got a flu jab or a Tdap, they were surprised to discover that the difference still held true. While the difference in hazard ratio was quite small, it happened over a large number of people and was a consistent size meaning it was unlikely to be a coincidence.
None of these factors alone or combined reduced the chances of being diagnosed with dementia within six years as much as the shingles vaccine.
Notably, the type of shingles vaccine did not matter either. The dementia delay occurred at similar rates with different shingles vaccines. The magic ingredient here seems to be preventing the shingles virus from getting busy.
Chicken Pox Redux
The same bug that causes chicken pox causes shingles- the varicella-zoster virus. If you had chicken pox earlier in life, you may well have some of the virus lurking in your body.
Once your immune system beat the initial infection and cleared up the itchy chicken pox rash, it’s likely that a few holdout viral particles managed to hide out in your nerve cells. This is a pretty devious hiding place, since your immune system can’t get at them there. The virus can sneak around your body through the long neuronal bodies.
Some people can go their whole life with their immune system quietly clearing the virus every time it tries to creep out, but others will be struck down with shingles. Shingles manifests as a painful blistering rash on the skin. It often turns up in strips following the path of a neuron.
Chicken pox Shots Prevent Shingles Too
Getting your kids vaccinated against chicken pox is a great way to make sure that your child will not only avoid chicken pox, but will not be at risk of developing shingles later in life. For the rest of us who fought off the ‘pox during childhood, getting a shingles vaccine is a great way to avoid a nasty break out.
Time will tell whether the link between the varicella-zoster shingles vaccine and delayed signs of cognitive decline holds up, but while we are waiting, holding off shingles too isn’t a bad plan.
Taquet M, Dercon Q, Todd JA, Harrison PJ. The recombinant shingles vaccine is associated with lower risk of dementia. Nat Med. Published online July 25, 2024:1-5. doi:10.1038/s41591-024-03201-5
