Idea density

In The End of Memory: A Natural History of Aging and Alzheimer’s, Jay Ingram devotes an entire chapter to “The Nun Study,” a project that started three decades ago with 678 participants and continues today in seven monasteries ranging from Minnesota to Texas to Connecticut. A nun named Sister Mary, who lived past 100, was the first to bequeath her brain to research. According to Ingram, when Sister Mary took the Mini-Mental State Examination near the end of her life, her score was almost seven times higher than what someone her age was expected to achieve.

Her autopsy was a shocker. Despite her high-end test scores, her brain was full of plaques and tangles, the telltale features of Alzheimer’s. As Ingram put it, “Sister Mary should have been demented.” Under the microscope, her brain tissue looked as diseased as Auguste Deter’s, the first patient to be diagnosed with what we now call Alzheimer’s disease. (When interviewed by Dr. Alois Alzheimer in 1901, Deter, a woman in her early fifties, could not recall her husband’s name.) How was it possible that Sister Mary could have so much tau and amyloid protein in the brain and still be cogent?

The answer is connected to a fantasy of mine. My strongest skill set—writing and editing—has remained largely intact, even though many other skills have been gradually weakening. This seems to be an example of “cognitive reserve,” the notion that some people with Alzheimer’s have certain skill sets that they retain deep into the disease’s progression, while other skills atrophy. But according to Ingram, possessing good writing skills around the age of twenty somehow helps protect the brain decades later from Alzheimer’s. The evidence is connected to essays written many decades ago by novitiates around the age of twenty.

 Two concepts are involved, “idea density” and “grammatical complexity.” Idea density, to me, sounds like what writers and journalists call “writing tightly”: the jettisoning of every unneeded word or phrase to maximize the sentence’s clarity and impact. Grammatical complexity is measured by the number of clauses, dependent or independent, in each sentence.

By my senior year in high school, I was writing with syntactical sophistication, pretty much the way I write today. But for my purposes, and for Ingram’s, idea density is the more relevant concept. As a young writer, I aimed to follow the models of Ernest Hemingway and George Orwell, each of whom made clarity and conciseness central tenets. But how might sophisticated writing as a young adult be a protective feature against the ravages of Alzheimer’s many decades later? As Ingram puts it, “It sounds bizarre, but in the case of the two fictitious essays [cited], the author of the first one would have been much more likely to die of Alzheimer’s than the second.”

Perhaps the most interesting aspect of Ingram’s book is his suggestion that Alzheimer’s may be a more fluid category than commonly assumed. About two out of five nuns enrolled in the Nun study “had measurable memory deficits, even though they were still in these first two stages. Findings like these have led to the belief that there is no chasm between normal mental functioning and Alzheimer’s disease” [My italics]. Rather, “normal functioning slides almost imperceptively into mild cognitive impairment…which, not always, but often, then moves into Alzheimer’s.”

Near the end of this illuminating chapter, Ingram comments, “Formal education, or something related to education [author’s italics], provides some type of cognitive or neural reserve.” A couple paragraphs later he asks, “How do a few years of education lessen impact of plaque accumulation sixty years later?”

I have no idea, and from what Ingram writes, the effect appears to be mysterious to him as well. What I do understand is this: Education is even more important than people assume.