"Higher Blood Pressure May Lead to Brain Shrinkage"
It is clear that hardening of the arteries inside our brain
and cognitive decline travel hand in hand,
something I’ve addressed before.
However, the independent association of Alzheimer’s
with multiple atherosclerotic vascular disease risk factors
suggests that cholesterol is not the sole culprit in dementia.
One of the most consistent findings is
elevated levels of blood pressure in midlife,
meaning ages 40 through 60, is associated with elevated risk
of cognitive impairment and Alzheimer’s dementia later in life.
In fact, even more so than having the so-called Alzheimer’s gene.
The normal arterial tree, all the blood vessels in the brain,
is designed as both a conduit and cushion.
But, when the artery walls become stiffened,
every time our heart pumps blood up into our brain,
the pressure from the pulse can damage small vessels in our brains.
This can cause what are called microbleeds in our brain,
which are frequently found in people with high blood pressure,
even if they were never diagnosed with a stroke.
These microbleeds may be one of the important factors
that cause cognitive impairments, perhaps not surprisingly,
because on autopsy, microbleeds may be associated
with brain tissue necrosis, meaning brain tissue death.
And, speaking of tissue death, high blood pressure is also associated
with so-called lacunar infarcts,
from the Latin word lacuna, meaning hole.
These are holes in our brain that appear
when little arteries get clogged in our brain
and result in the death of a little round region of the brain.
Up to a quarter of the elderly have these little ministrokes,
and most don’t even know it, so-called silent infarcts,
but no black holes in the brain are benign.
This is what they look like—
it’s like your brain has been hole-punched.
Although silent infarcts, by definition,
lack overt stroke-like symptoms,
they are associated with subtle deficits in physical
and cognitive function that commonly go unnoticed.
And, they can double the risk of dementia.
That’s one of the ways high blood pressure is linked to dementia.
So much damage that high blood pressure levels
can lead to brain volume reduction, literally a shrinkage of our brain,
specifically in the hippocampus, the memory center of the brain.
This helps explain how high blood pressure
can be involved in the development of Alzheimer’s disease.
One can actually visualize the little arteries in the back of our eyes,
using an ophthalmoscope, providing a noninvasive window
to study the health of one’s intracranial arteries,
the little vessels inside our head.
The researchers found a significant association
between arterial disease and brain shrinkage on MRI.
But, this was a cross-sectional study, just a snapshot in time;
so, you can’t prove cause and effect.
What you need is a prospective study, following people over time;
and so, that’s what they did.
Over a 10 year period, those with signs of arterial disease
were twice as likely to suffer a significant loss
of brain tissue volume over time.