1: Up until the late 1960s, doctors and scientists believed that “senile dementia” was not a disease, but just a normal consequence of aging.
Then, three British psychiatrists, Garry Blessed, Bernard Tomlinson, and Martin Roth, “examined the brains of seventy patients who had died with dementia,” Dr. Peter Attia writes in Outlive, “and found that many of them exhibited the same kinds of plaques and tangles” that Alois Alzheimer had first observed more than fifty years earlier.
Additional research showed that the degree of cognitive impairment correlates with the amount of plaques found in the brain.
“The brain is a greedy organ,” Peter notes. “It makes up just 2 percent of our body weight, yet it accounts for about 20 percent of our total energy expenditure.
“Its eighty-six billion neurons each have between one thousand and ten thousand synapses connecting them to other neurons or target cells, creating our thoughts, our personalities, our memories, and the reasoning behind both our good and bad decisions.”
What Peter calls “the beautiful machine that is the human brain” is powered not by electricity, but rather by a “steady supply of glucose and oxygen, delivered via a huge and delicate network of blood vessels.”
2: The evidence shows that robust blood flow seems critical to maintaining brain health.
Case Western Reserve neurologist Jack de la Torre believes that dementia symptoms are the result of a gradual reduction in blood flow to the brain, which over time creates a “neuronal energy crisis.”
“We believed, and still do, that amyloid-beta is an important pathological product of neurodegeneration,” Jack writes, “…[but] it is not the cause of Alzheimer’s disease.”
“The amyloid plaques and tangles come later,” Peter writes, “as a consequence rather than a cause.”
There is evidence to support this theory: “Alzheimer’s is more likely to be diagnosed in patients who have suffered a stroke, which typically results from a sudden blockage of blood flow in specific regions of the brain,” Peter writes. “In these cases, symptoms emerge abruptly, as if a switch has been flipped. . .
“In all, some two dozen risk factors for Alzheimer’s disease also happen to reduce blood flow, including high blood pressure, smoking, head injury, and depression, among others. The circumstantial evidence is strong.”
3: Elevated glucose levels in the blood also impact the risk of developing Alzheimer’s disease.
Insulin resistance is a hallmark of Type-2 diabetes. The body’s cells don’t respond effectively to insulin, which causes blood glucose levels to rise because the liver continues to produce glucose even when it’s not needed.
“Having type 2 diabetes doubles or triples our risk of developing Alzheimer’s disease,” Peter writes. “On a purely mechanistic level, chronically elevated blood glucose, as seen in type 2 diabetes and prediabetes/insulin resistance, can directly damage the vasculature of the brain.”
Research suggests insulin plays a vital role in memory function.
“Insulin receptors are highly concentrated in the hippocampus, the memory center of the brain,” Peter notes. “Several studies have found that spraying insulin right into subjects’ noses—administering it as directly as possible into their brains—quickly improves cognitive performance and memory, even in people who have already been diagnosed with Alzheimer’s disease.”
The authors of one study conclude: “Several lines of evidence converge to suggest that central insulin resistance plays a casual role in the development and progression of Alzheimer’s disease.”
No post tomorrow. So, more to come after New Year’s!
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Reflection: What are my thoughts on the connection between Type 2 diabetes and Alzheimer’s disease?
Action: Talk to my doctor about what I can do to reduce my risk of diabetes.
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