Could Asking People How They Feel Help Predict Dementia?

Imaging the living brain, searching for telltale molecules in the
cerebrospinal fluid, and measuring memory and thinking skills—these are
among the tests scientists use to figure out who might eventually
develop Alzheimer’s disease (AD). But what about asking a simple
question: “How do you feel?” In an age of advanced technologies, this
may seem a rudimentary way to predict disease, but a number of recent
studies claim that a person’s own perception of health is as good an
omen as any of future dementia. The latest evidence to bolster this
claim appears in the October 5 Neurology online by researchers for the Three-City (3C) Study in France.

The 3C study observes community residents 65 and older from Bordeaux,
Dijon, and Montpellier to determine the influence of various factors on
the risk of dementia. By asking the 8,169 participants to rate their
health and then following them for up to eight years, researchers led by
Christophe Tzourio of the Hopital de la Salpêtrière, Paris, found that
people who rated their health as poor were more likely to develop
dementia than those who rated it fair, and even more so than those who
felt they were in good health. Two earlier papers also pointed to a
connection between people’s health ratings and dementia (Weisen et al., 1999; Yip et al., 2006), but this latest study is the largest.

“This study suggests that there is some value in asking people
not just about specific medical conditions, but also more generally
about their overall perception of wellness,” wrote Murali Doraiswamy at
Duke University, Durham, North Carolina, in an e-mail to ARF. “It sends
the message that we should treat the person, not the disease; i.e., we
need to pay more attention to asking people about their feelings rather
than just relying on what the biomarker tests show.” That is not to say
that asking people how they feel can replace objective tests or will be
enough to make a diagnosis or prescribe a medication. Rather, it should
be something of which doctors take note, suggested Tzourio. “A doctor
should ask this very natural question, ‘How would you rate your health?’
If a person rates it poorly and there is no obvious medical reason for
saying that, and the patient is not depressed, then maybe [he or she]
should be followed more closely for possible signs of dementia in later
years,” he said.

None of the people recruited to the 3C study had a severe
disease, such as cancer or diabetes. Some 5 percent rated their health
as very poor or poor, 35 percent as fair, and 60.3 percent as good or
excellent. After about eight years, 618 people in the study had
dementia—either AD (68 percent), vascular dementia (7 percent), or other
types (25 percent). Controlling for known dementia risk factors such as
little education, a history of depression, or previous complaints with
memory or thinking, the researchers determined that the risk of dementia
was 70 percent higher in people who had rated their health as poor and
34 percent higher in people who rated it as fair, than in those who had
considered their health good. “At first, we thought it was possible that
people rated their health as bad because they were depressed, and the
depression was what put them at higher risk for dementia, but instead we
found that the relation between self-reported health and dementia
remained, even in people without depression,” said Tzourio.

The association emerged in people without any earlier memory
complaints or thinking problems; they were twice as likely to develop
dementia if they had rated their health as poor than if they had said it
was good. “Right now, if people tell their doctor that they are having
problems remembering things, that is taken as a possible warning sign of
dementia [that warrants further testing],” said Tzourio. “The same
should be true of poor general health.”

Researchers are beginning to realize that age-related health
factors not normally associated with AD may predict dementia
independently of more established and specific ones, such as depression
or memory complaint (see ARF related news story on Song et al., 2011 and Holmes et al., 2011).
“Self-reported health is not a traditional risk factor for dementia. It
is very nonspecific. It says that several years before patients have
overt symptoms of dementia, they know something is wrong,” said Deborah
Barnes at the University of California, San Francisco, who was not
involved in the 3C study. “Nonspecific predictors can be useful,
especially when other predictors are not present,” added Barnes, who has
been incorporating health-related questions and biomarkers to develop a
tool for predicting dementia risk (Barnes and Yaffe, 2009).

Because people’s own assessment of their health is such a “fuzzy”
measurement, it is hard to say what it means in terms of dementia
development and why there would be a connection between the two. One
possibility, said Tzourio, is that if people have memory problems, an
early sign of dementia, they might not recognize them as such, but
rather say they are not feeling well. Another possibility is that people
who say they don’t feel well end up going out less to socialize with
others or to exercise; this might put them at higher risk for developing
dementia (see ARF related news story).

Clive Holmes at the University of Southampton, U.K., favors yet
another explanation. His work has shown that people with AD have higher
levels of proinflammatory cytokines, and that these cytokines predict
faster cognitive decline in AD patients (Holmes et al., 2009).
“In this study they looked at a generalized feeling. My hypothesis is
that what they are picking up is systemic inflammation, which makes
people feel unwell,” said Holmes. Chronic inflammation is a known risk
factor for AD (see ARF related news story), and a number of genes involved in inflammation are in the Top 10 AlzGene list.—Laura Bonetta.

Montlahuc C, Soumaré A, Dufouil C, Berr C, Dartigues J-F, Poncet M,
Tzourio C, Alpérovitch A. Self-rated Health and Risk of Incident
Dementia: A Community-based Elderly Cohort, the 3C Study. Neurology 2011
Oct. 11; 77:1457-1464. Abstract


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