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Study Looks Into Roots of Alzheimer's
Brain Area for Daydreaming Is Affected
By Shankar Vedantam
Washington Post Staff Writer
Wednesday, August 24, 2005; A09
The brain areas involved in daydreaming, musing and other
stream-of-consciousness thoughts appear to be the same regions targeted
by Alzheimer's disease, researchers are reporting today in an unusual
study that offers new insights into the roots of the deadly illness.
The strong correlation between the two suggests there might be a link
between the sort of thinking that people regularly do when not involved
in purposeful mental activity and the degenerative disease that is
characterized by forgetfulness and dementia, said scientists who
conducted the federally funded study.

Randy Buckner, a neuroscientist at Washington University in St. Louis,
said the implications of the finding are far from clear. It is too early
to suggest that daydreaming is dangerous, he said, or that avoiding such
musings could affect the risk of Alzheimer's disease. Rather, he and
others said, the study adds to the evidence that everyday mental and
physical activities play an important role in the course of neurological
disease.
"It suggests an avenue between brain activity patterns and Alzheimer's
disease that we just hadn't been thinking about," said Buckner, who led
the study. "It is going to take some time to understand the relative
potential of this link."
Other neuroscientists agreed the work was intriguing -- and joked about
its implications.
"There goes half my day," Ronald Petersen, director of the Mayo Clinic's
Alzheimer's Disease Research Center, said about his own propensity for
creative musing.
"It is really going out on a limb," he added of the new study. "But for
the sake of generating discussion, it is interesting. It is useful to
get people thinking along these lines."
Further research is underway to probe the link, said Buckner, who is
affiliated with the Howard Hughes Medical Institute in Chevy Chase.
While some unknown third factor may be responsible for triggering
daydreaming as well as Alzheimer's, the neuroscientist said a causative
link between the two would explain a mystery that has long bothered
scientists: why Alzheimer's generally affects memory first.
"When we muse to ourselves and plan our day and think about the recent
past, we tend to use memory systems," Buckner said. "Through some
as-yet-unknown pathway or metabolism cascade, use of these systems may
be what underlies Alzheimer's disease."
Although daydreaming is usually seen as intellectual downtime, Buckner
said that might not be true. Such musings are far from passive, he
added, and might help people be creative.
But the undirected thought patterns that most people slip into readily
may result in the kind of "wear and tear" that ends in Alzheimer's
disease, Buckner said.
This theory, however, clashes with the evidence that intellectual
activity plays a protective role against Alzheimer's disease. Far from
the "wear and tear" model, other research has suggested that the brain
runs on a "use it or lose it" system.
Buckner and other neuroscientists acknowledged the contradiction -- and
put it down to the preliminary state of the research.
"To be honest, all of these should be taken with a grain of salt,"
Petersen said of the various theories of risk factors and protective
factors. Because Alzheimer's typically strikes the elderly,
high-quality, long-term studies that track people for decades are
difficult to conduct.
Although Buckner's study focused on one aspect of Alzheimer's -- the
buildup of amyloid plaques in the brains of patients -- Petersen said it
is still not clear what role the plaque plays in the disease or how it
is linked to another signature of the disease, tangles of nerve fibers.
The tangles, Petersen said, may be more linked to changes in cognitive
activity than the plaques.
The new study, which is being published today in the Journal of
Neuroscience, made use of several advances in brain imaging. Different
techniques allowed scientists to map the complex brain patterns of young
adults while they were daydreaming and to compare those findings with
more recent research pinpointing the location of amyloid plaques in the
brains of Alzheimer's patients.
In all, Buckner's team used data from 746 participants. Buckner said he
was surprised to find a "remarkable" correlation between the regions
involved in daydreaming and the location of the plaques.
"I don't want to imply if one didn't do those things one would not get
Alzheimer's disease," he said. "It may be that Alzheimer's disease
arises from normal brain function. . . . It could be that while we are
well positioned to lead long lives, we were not built to live as long as
we do."
Lon Schneider, a psychiatrist at the University of Southern California,
said the idea that Alzheimer's could be linked to repetitive thought
patterns has parallels with diseases such as depression, in which
repetitive worries and obsessions are linked to brain changes.
But, like the other scientists, he cautioned about drawing inferences
about preventive techniques.
"I look forward to the public health campaign to stop people from
engaging in these dangerous, risky behaviors," he quipped. "Maybe we can
equip ourselves with anti-daydreaming monitors that shock us when we
slip into reverie."
© 2005 The Washington Post Company
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