 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 mid-life, meaning ages 40 through 60, is associated with elevated risk of cognitive impairment in 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 bled 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 lacuna infarcts, from the Latin word lacuna, meaning whole. 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 mini-strokes, 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're 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 non-invasive 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. 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.