Scientists have long known that heart health and brain health are closely connected. Conditions such as high blood pressure, diabetes, stroke, and heart disease have all been linked to a greater risk of developing dementia later in life.
However, researchers are still trying to understand whether the genes that increase the risk of these conditions might also play a role in dementia.
A new study published in Neurology provides some important clues. Researchers found that people who inherited a greater number of genetic variants linked to higher pulse pressure had a slightly higher risk of having dementia listed as a contributing cause of death.
The findings suggest that some of the genes affecting cardiovascular health may also influence the way dementia develops later in life.
Pulse pressure is a measurement that many people have never heard of, even though it comes directly from a standard blood pressure reading. Blood pressure is recorded using two numbers.
The top number, called systolic pressure, measures the force of blood when the heart beats. The bottom number, called diastolic pressure, measures the pressure when the heart rests between beats. Pulse pressure is simply the difference between these two numbers.
A high pulse pressure can be a sign that arteries are becoming stiff or that the heart and blood vessels are not working as efficiently as they should. Previous research has shown that higher pulse pressure is associated with poorer cardiovascular health and may contribute to damage in blood vessels throughout the body, including those that supply the brain.
The study was led by Dr. Laura M. Raffield from the University of North Carolina at Chapel Hill. Her team wanted to know whether genetic factors that increase the risk of cardiometabolic diseases could also influence dementia risk.
The researchers analyzed data from 8,818 adults who were around 64 years old on average when the study began. Participants were followed for as long as 14 years for dementia-related death and approximately nine years for changes in cognitive function.
Each participant underwent genetic testing. The researchers examined many small differences in DNA and used them to create what are known as polygenic risk scores. These scores estimate a person’s inherited tendency toward certain diseases based on the combined effects of many genetic variants.
The team created risk scores for eleven different cardiometabolic conditions and risk factors, including blood pressure, cholesterol levels, triglycerides, type 2 diabetes, stroke, coronary artery disease, atrial fibrillation, and blood clotting disorders. They also created a separate genetic risk score for Alzheimer’s disease and related forms of dementia.
Throughout the study, participants completed regular cognitive assessments. By the end of the research period, 619 people had developed cognitive impairment. Researchers also reviewed death records to determine whether dementia was listed as either a primary or contributing cause of death.
A total of 456 people had dementia listed on their death records. After accounting for factors such as age, sex, and other genetic influences, the researchers found that people with higher genetic risk scores for pulse pressure had a 16% greater likelihood of having dementia listed as a contributing cause of death.
Interestingly, the researchers did not find similarly strong links for the other cardiometabolic conditions they studied. They also did not find strong evidence that these genetic risk factors were associated with early cognitive impairment.
The findings suggest that genetic factors related to pulse pressure may be more closely connected to the later stages of dementia rather than the earliest signs of memory decline. According to the researchers, this may point to shared biological pathways between cardiovascular health and dementia progression.
The study does not prove that genes linked to higher pulse pressure directly cause dementia. Instead, it shows an association between the two. Other factors may also contribute to the relationship, and more research is needed to understand the underlying mechanisms.
One limitation of the study is that dementia may not always be recorded accurately on death certificates. As a result, some cases could have been missed. In addition, the increase in risk was relatively small, meaning that pulse pressure genetics is only one of many factors that may influence dementia outcomes.
Overall, the research provides another piece of evidence that heart health and brain health are deeply connected. The study’s strength lies in its large sample size and long follow-up period.
However, the results should be viewed as an early clue rather than definitive proof. Future studies will need to determine exactly how these genetic factors affect the brain and whether improving cardiovascular health can help reduce dementia risk in genetically vulnerable individuals.
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Source: University of North Carolina at Chapel Hill.
