How Damaged Blood Vessels Cause Dementia, Study Provides Genetic Evidence

A new study has provided genetic evidence linking a common condition of the blood vessels in brain to dementia and Alzheimer’s disease.

Known as white matter hyperintensity (WMH), the condition marked by lesions in the brain, is a common feature of the cerebral small-vessel disease, which involves the narrowing of the blood vessels thereby obstructing blood flow, potentially resulting in strokes.

By damaging blood vessels, cerebral small-vessel disease is thought to be the main contributor to cognitive decline and dementia, in which one’s memory and ability to think is affected, thereby impacting daily activities and living. Alzheimer’s disease is the most common form of dementia.

According to the study’s authors, led by those at the University of Texas, US, “causal evidence” of WMH lesions leading to stroke and dementia has been limited. Although previous studies have found that these lesions, which appear as bright areas in MRI brain scans, increase the risk of such neurologically deteriorative conditions.

The study, published in The Journal of the American Medical Association (JAMA) Network Open, showed genetic evidence of blood vessel-related (vascular) damage in the brain can result in dementia.

The researchers first estimated the genetic risk of developing WMH, stroke and blood pressure in an individual. In the second stage, they compared these risks with people actually developing dementia, data for which were taken from population-level studies published between 1979 and 2018. The two-year-long analysis included up to 75,000 dementia cases with European ancestry.

“As vascular disease is a treatable contributor to dementia risk, our findings have broad significance for prevention strategies of Alzheimer’s and dementia as a whole,” first author Muralidharan Sargurupremraj, an assistant professor at the University of Texas Health Sciences Center, said.

With about 75 million people around the world expected to develop dementia by 2030, the researchers said that devising strategies to prevent or delay its occurrence is a major public health priority.

Future studies could examine whether their findings can be applied more widely to non-European populations, the authors said.