Saturday, May 23, 2009

Dementia is normal - and what that means

In a post-industrial age of low birth rates the greatest economic challenge for wealthy nations is acquired cognitive disability -- better known as dementia.

So we ought to think clearly about dementia. It doesn't help that my generation of physicians were taught to think of dementia as an "abnormal" disease like the flu, rather than an all-but-inevitable consequence of aging.

A recent popular review, which was ironically intended to be inspiring, underscores how "normal" (typical) dementia is (emphases mine) ...
... In recent years scientists have become intensely interested in what could be called a super memory club — the fewer than one in 200 of us who ... have lived past 90 without a trace of dementia....
... Laguna Woods, a sprawling retirement community of 20,000 south of Los Angeles, is at the center of the world’s largest decades-long study of health and mental acuity in the elderly. Begun by University of Southern California researchers in 1981 and called the 90+ Study, it has included more than 14,000 people aged 65 and older, and more than 1,000 aged 90 or older.
... researchers have also demonstrated that the percentage of people with dementia after 90 does not plateau or taper off, as some experts had suspected. It continues to increase, so that for the one in 600 people who make it to 95, nearly 40 percent of the men and 60 percent of the women qualify for a diagnosis of dementia.
... it is precisely that ability to form new memories of the day, the present, that usually goes first in dementia cases, studies in Laguna Woods and elsewhere have found.
The very old who live among their peers know this intimately, and have developed their own expertise, their own laboratory. They diagnose each other, based on careful observation....
...Here at Laguna Woods, many residents make such delicate calculations in one place: the bridge table.
Contract bridge requires a strong memory. It involves four players, paired off, and each player must read his or her partner’s strategy by closely following what is played. Good players remember every card played and its significance for the team. Forget a card, or fall behind, and it can cost the team — and the social connection — dearly.
“When a partner starts to slip, you can’t trust them,” said Julie Davis, 89, a regular player living in Laguna Woods. “That’s what it comes down to. It’s terrible to say it that way, and worse to watch it happen. But other players get very annoyed. You can’t help yourself.”
... Later, the partner stares uncertainly at the cards on the table. “Is that ——”
“We played that trick already,” Ms. Cummins says. “You’re a trick behind.”
Most regular players at Laguna Woods know of at least one player who, embarrassed by lapses, bowed out of the regular game. “A friend of mine, a very good player, when she thought she couldn’t keep up, she automatically dropped out,” Ms. Cummins said. “That’s usually what happens.”
Yet it is part of the tragedy of dementia that, in many cases, the condition quickly robs people of self-awareness. They will not voluntarily abandon the one thing that, perhaps more than any other, defines their daily existence...
... In studies of the very old, researchers in California, New York, Boston and elsewhere have found clues to that good fortune. For instance, Dr. Kawas’s group has found that some people who are lucid until the end of a very long life have brains that appear riddled with Alzheimer’s disease. In a study released last month, the researchers report that many of them carry a gene variant called APOE2, which may help them maintain mental sharpness.
Dr. Nir Barzilai of the Albert Einstein College of Medicine has found that lucid Ashkenazi Jewish centenarians are three times more likely to carry a gene called CETP, which appears to increase the size and amount of so-called good cholesterol particles, than peers who succumbed to dementia...
Imagine how hellish that bridge table can be. Every game, a test. Show weakness, slip, and death is your fate. First social death, then the grave. It makes professional baseball look like ... child's play.

I'd bet a good amount that the "protective" "social" effect of playing bridge is bull poop. This is all about a survivor-effect correlation. Only the genetically gifted slow agers can play. On the other hand, I doubt that even the best of those bridge players could handle a modern knowledge worker job -- they are good for their age, but they are not immortal.

So if we (mostly) set aside wistful hopes of some kind of mental activity that protects against normal, all-but-inevitable, age related dementia, what do we have left to learn from these and similar studies?

We know it helps to be born clever, but that only gives your airplane more fuel -- it doesn't by itself slow the normal process of brain mush. Many brilliant thinkers with, at their peak, one in a million minds, are relatively disabled by their 70s - though still better off than most of us.

We can't do much with the brains we're born with, but we do have animal model evidence, and less definitive human evidence (because we don't randomly experiment then autopsy humans), that physical exercise is protective against normal dementia. Seems bizarre to me, but it holds up. On the other hand, head injury accelerates dementia, so don't make your exercise football, contact hockey, boxing, or horse jumping.

Exercise and head whacks aside, this is all about genes and medicines. It's about identifying those whose brains hold up longer, then figuring out the trick of it, then looking for a medicine that will help the average person. It's slow, hard work, but success is worth trillions in economic growth and a significant reduction in human suffering. By that metric, we're grossly underfunding this research. The potential payoff is enormous compared to say, cancer research. (I've been pointing this out, incidentally, for at least twenty years. It's not hard to do the math.)

Barring any breakthroughs, however, we boomers need to get real about our future. We expect we're going to have to keep working to 70 or beyond, but you can't cheat mother nature. Dementia is the end-point of a disabling process that starts, for most of us, when we're about 25. We'll be working, but we'll be doing more grocery bagging than particle physics.

Maybe we should think about how to make the less cognitive life more appealing. Maybe we ought to think about how society supports those with cognitive disabilities at all ages ...

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