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Sure enough,
he found that the sisters with high folate levels showed little
evidence of Alzheimer's-type damage in their brain after death.
This makes a certain amount of sense; folate tends to counteract
the effects of homocysteine, an amino acid produced in the
body that has been implicated in cardiovascular disease. Plenty
of folate in the blood would thus mean less chance of stroke
- and might even protect brain cells from damage by homocysteine
in the brain.
Unfortunately,
the other micronutrients haven't panned out so well. It makes
sense that antioxidants like vitamin E and vitamin C, which
soak up cell-damaging "free-radical" molecules in the body,
would protect against cell destruction. Although vitamin E
looked promising in an earlier study, neither substance had
an obvious effect on the Notre Dame sisters. Nor, on the other
side of the equation, did mercury or aluminum in the diet,
both of which had been implicated in earlier studies as possible
triggers for Alzheimer's.
But another
hunch turned out to be far more productive. When Snowdon and
Kemper first read the sisters' autobiographies in the early
1990s, they noted that the writings differed not just in the
density of ideas they contained but also in their emotional
content. "At the time," he says, "we saw that idea density
was much more related to later cognitive ability. But we also
knew that there was something interesting going on with emotions."
Studies by other scientists had shown that anger and depression
can play a role in heart disease, so the team decided to take
another look.
This time
they searched for words suggesting positive emotions (such
as happiness, love, hope, gratitude and contentment), as well
as negative ones (sadness, fear, confusion and shame). Snowdon
found that the sisters expressing negative emotions did not
live as long as the sisters conveying more positive ones.
He has already begun another analysis, comparing the emotional
content of the nuns' early autobiographies with the ones they
penned in late life, as part of the Nun Study. As mental abilities
decline, his preliminary review has found, the expression
of positive emotions also drops. While he suspects the whittling
away of positive feelings are a consequence of the neurological
changes of Alzheimer's, it is still possible that emotional
states may play a role in determining cognitive function.
To find out, Snowdon will next compare the emotional content
of the sisters' writings with their autopsied brains, to see
if positive emotions work to keep nerve connections snapping
and if negative emotions dampen and eventually extinguish
them.
By now,
15 years after he first climbed Good Counsel Hill, Snowdon
has identified half a dozen factors that may predict or contribute
to Alzheimer's disease. He could sit each sister down right
now and tell her what her chances are. But should he? As he
has all along, Snowdon will put his dilemma to the sisters
themselves: next month he will meet with the Notre Dame leadership
to discuss whether to break the news to the high-risk nuns
- and how to answer the inevitable questions about what they
might do to prevent or slow down the disease.
"So far,"
he says, "I have a certain comfort level in making some recommendations
because there are other good reasons for preventing strokes,
for reading, for taking folic acid. If our findings showed
something that had no other known benefit besides preventing
Alzheimer's, then we would be on much thinner ice." Even so,
it's not clear precisely how much folic acid to take, and
Snowdon's team is divided on whether to boost the intake of
vitamins C and E beyond the normal recommended doses (Markesbery
says yes; Snowdon says not until we know more).
These questions
will become more urgent as the population bulge of the baby
boom generation reaches the Alzheimer's years - and new research
is showing that those years may start earlier than anyone
had thought. Just two months ago, scientists suggested that
many cases of a condition known as mild cognitive impairment,
in which patients in their 40s and 50s exhibit memory and
recall problems, are very likely the first step on the way
to Alzheimer's disease. If so, then it's important to start
slowdown strategies as soon as possible. A cure for Alzheimer's
is still the ultimate goal, but, says Snowdon, "until there
is a magic bullet that can stop the plaques and tangles from
growing, we're going to have to take a multipronged approach
that will include things like avoiding head injuries and strokes
and adding nutritional supplements like folate and antioxidants."
Meanwhile,
the Nun Study will continue. Snowdon and his team are attempting
to study the sisters' brains before they die, using mri scans
to track how the brain deteriorates with age and how such
changes correlate with those in speech, memory and behavior.
And to ensure that the sisters' generous gift to science will
continue to educate others, Snowdon is trying to have the
brain bank and archive records permanently endowed. That way,
future generations will continue to benefit from lessons that
women like Sisters Ada, Rosella and Nicolette are teaching
all of us about how to age with grace and good health.
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May 14, 2001 | No. 19
COVER
STORIES
The
Nuns' Stories
Hundreds of Roman Catholic sisters have opened up their lives, their memories
and (when they die) even their brains to researcher David Snowdon so that
all of us can better understand what causes Alzheimer's disease and what
can be done to prevent it
TRAVELER'S
ADVISORY
SOCIETY
BEHAVIOR: The Talking Cure...
Australian schools try shaming troublemakers onto the right path
THE
ARTS
CINEMA: Goodbye, Mrs. Tom Cruise. Hello, Nicole
Kidman, star of a bold new movie... Moulin Rouge awakens the dormant
musical
Samantha Lang, a cinematic connoisseur
of sex
MUSIC: Nick Cave, the gloom rocker, blooms
BOOKS: A slim prayer with sales that are
divine
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