Now let's talk about vascular dementia. This is one of the most common causes of an
acquired dementia. It's the second most common cause of dementia in the elderly.
It's the product of chronic ischemia and also potentially multiple acute infarcts
that can occur on the brain. And the typical clinical manifestations include a decline
in cognitive ability with later onset memory impairment. And there are a couple of
key features that we want to hone in on. One is patients often develop a stepwise
progression of symptoms as opposed to slowly progressive linear development of
symptoms over time and memory impairment is often late which contrast with
Alzheimer's disease where memory impairment is often early. And here, we can see a
typical MRI for a patient with vascular dementia. We're looking at an axial flair
of the brain and we see around the ventricles this area of T2 flare hyperintensity.
Those areas around the ventricle are the small vascular beds and with longstanding
vascular disease we see damage to the small arterioles which contribute to the
development of cognitive decline and dysfunction. So what's going on in the brain to
contribute to vascular dementia? There are a few things I want you to remember.
First is vascular dementia results from a combination of risk factors and likely genetic
variants. It's that interplay between genetic risk and environmental insults.
And there's a number of things that are happening within the blood vessels and
brain that can contribute to vascular dementia. We can see white matter disease
and white matter dysfunction, microinfarcts that contribute to cognitive dysfunction,
large territory infarcts that can result in a prominent step of cognitive decline and
subsequent brain atrophy. Some patients may experience wider spread white matter
disease, other more significant large infarcts, but the final common pathway
is the same and that is the onset of cognitive dysfunction slowly and step-wise
over time as a result of these changes. When we think about the natural history,
vascular dementia can follow several different courses. One of the most common
is the multi-infarct dementia where multiple areas of large vessel arterial occlusion
results in accumulation of cognitive deficits over time. After each stroke, the
patient just doesn't return back to normal, and you can see that in the top curve
here. Subcortical vascular dementias or large arterial strokes are not the
contributor but that small vessel vascular disease is driving cognitive dysfunction
tend to follow a more gradually progressive course. And then single infarct
dementia can occur where a significant enlarged stroke results in substantial decline
without recovery in cognitive function. And so each of these time courses and
natural history would be consistent with vascular dementia but from different
underlying brain pathology.