The stiffening of blood vessels due to cross-linking in the extracellular matrix and other factors such as calcification is known to cause hypertension, and the elevated blood pressure of hypertension causes progressive damage to brain tissue. The degree to which this damage occurs - and might be blamed for cognitive decline with aging - is becoming ever more clear as scanning technologies improve:
A new imaging technique found that some people with high blood pressure also have damage to nerve tracts connecting different parts of the brain. The area of brain damage detected is linked to difficulties in certain cognitive skills, decision-making, and the ability to regulate emotions. "We already have clear ways to explore the damage high blood pressure can cause to the kidneys, eyes, and heart. We wanted to find a way to assess brain damage that could predict the development of dementia associated with vascular diseases." While there has been a lot of research on hypertension-related brain changes in the grey matter, scientists proposed that a look into the brain's white matter could tell if high blood pressure was having an effect even earlier than what is known.
Researchers used diffusion tensor imaging (DTI), an enhancement of magnetic resonance imaging (MRI), to evaluate and compare the structural and functional properties of the main connections between different brain regions. Fifteen participants were on medication for moderate to severe high blood pressure and 15 participants had normal blood pressure. Participants were also given a cognitive assessment. The brain imaging found that, while none of the participants showed abnormalities on a standard MRI, the more advanced DTI revealed that participants with high blood pressure had damage to: 1) brain fibers that affect non-verbal functions; 2) nerve fibers that affect executive functioning and emotional regulation; and 3) limbic system fibers, which are involved in attention tasks. Researchers also found those with high blood pressure performed significantly worse on two different assessments of cognitive function and memory. However, there were no differences in tests evaluating verbal function or ability to perform daily activities.