Previous studies have shown a link between high blood pressure in midlife and later dementia. Some research suggests treating midlife high blood pressure lowers the risk of developing dementia, although this reduction may be small. [Treating high blood pressure late in life may not reduce that risk.]
The link between dementia and inflammation is a bit more theoretical. The researchers at VU University Medical Center looked at levels of proteins in the blood that suggest a person has a high level of inflammation, and found no difference between those with a parental history of Alzheimer’s and those without. But when they exposed each person’s blood to a substance that causes an immune system response, the blood of people from the group with the family history of Alzheimer’s produced a high level of inflammation-causing proteins. Some people, perhaps because they carry certain genetic variations, may react more strongly to an infection anywhere in the body. In theory, this strong reaction produces a higher than average level of inflammation in the brain, contributing to Alzheimer’s.
It’s not clear that higher blood pressure and a tendency towards inflammation mean individuals in this group will develop dementia. If funding becomes available, the VU University Medical Center researchers will continue to follow people who took part in the study to gather additional data.
In the meantime, Dr. van Exel thinks it’s important for middle-aged people with a family history of Alzheimer’s to control any high blood pressure. “The differences in blood pressure are not very large on an individual level,” he says. “However, in a group, a difference in blood pressure does have clinical relevance since by reducing blood pressure to normal values in large groups, we know that the incidence of dementia will be significantly reduced. Currently the only clinical evidence to reduce Alzheimer’s disease is by lowering high blood pressure. This study shows that this is especially important in offspring of parents diagnosed with Alzheimer’s.”
Note: Dr. van Exel would like to thank everyone who participated in this study, whether their parents had good cognitive function or were diagnosed with Alzheimer’s.