People with high blood pressure are exposed to anti-hypertensive medication which may protect them from Alzheimer’s disease.

The team only found a significant association between higher systolic blood pressure and reduced Alzheimer’s risk. "It’s likely that this protective effect is coming from anti hypertensive drugs," said co-author John Kauwe, Associate professor of biology at Brigham Young University, US.
"Our results are the opposite of what people might think," said co-author Paul Crane, associate professor of internal medicine at University of Washington.
"It may be that high blood pressure is protective or it may be that something that people with high blood pressure are exposed to more often, such as anti hypertensive medication, is protecting them from Alzheimer’s disease," said Crane.
"This is to date the most authoritative paper looking at causal relationships between Alzheimer’s disease and these potentially modifiable factors. In terms of the number of samples, it can’t get bigger at this point," said Kauwe.
Source-Medindia