Lower levels of "bad" LDL cholesterol could mean a lower risk of dementia and Alzheimer's disease, a new study says.

The findings suggest that the shingles virus might play a role in causing at least a subset of dementia cases, Geldsetzer says, and the vaccine may protect against that. Alternatively, it could be that certain vaccines, such as the one for shingles, lead to a broader immune system activation that lowers the risk of dementia developing.

Seniors who got the shingles vaccine when it became available in the U.K. were 20% less likely to develop dementia than those who did not take the jab, according to research published April 2 in the journal Nature.