Daydreaming, Alzheimer's disease may be linked

ST. LOUIS -- Scientists who set out to explore changes in the brain as Alzheimer's disease progresses got a surprise: a possible link between daydreaming and the degenerative brain disease that robs memory, language and thought.

A new Washington University study shows the part of the brain used to daydream is the same where Alzheimer's disease develops -- in some people -- later in life. It suggests the normal brain activity of daydreaming fuels the sequence of events leading to Alzheimer's.

"The implication, albeit a speculative one, is that those activity patterns in young adults are the foothold onto which Alzheimer's disease forms," said lead researcher Randy Buckner, associate professor of psychology.

He said they may lead to a lifelong cascade that ends in Alzheimer's disease in some people.

"It suggests a new hypothesis and opens an avenue in exploration," Buckner said. "By no means is it definitive."

The study is in this week's The Journal of Neuroscience.

Researchers at Washington University and the University of Pittsburgh used five imaging techniques to map the brains of 764 people. The subjects fell into three groups -- people in their 20s, and older people with either early-stage dementia, or Alzheimer's disease.

When they compared images, they found that parts of the brain involved in musing, daydreaming or recalling pleasant memories in young people were where evidence of Alzheimer's disease appears.

The hallmarks of Alzheimer's are brain lesions called plaques and tangles that are associated with nerve cells not communicating with each other and eventually dying.

The part of the brain involved in daydreaming is always active, even if the mind is at rest, said William Klunk, coauthor of the study and associate professor of psychiatry at the University of Pittsburgh. "It's like an engine on idle," he said. "It never shuts down. That activity might fuel the sequence of events that could lead to Alzheimer's."

He said the connection is a "problem."

"The answer is not shutting down our brains," Klunk said.

"It means it's very important to identify changes in the brain at early stages of illness, so that as newer interventions come along, we can start them at a time when it makes a difference."

Until very recently, the disease was diagnosed with certainty only after an examination of brain tissue in an autopsy. But brain imaging technology developed by Klunk can detect the identifying plaques and tangles.

The imaging techniques exist in research settings but are not yet a routine clinical tool.

Buckner said even though his research correlates brain activity with Alzheimer's, "there's a lot of evidence that suggests engaged cognition is a good thing. That's the advice I'd give my family."

Neil Buckholtz, chief of the dementias of aging branch at the National Institute on Aging, which funded the study, said the data are interesting even if the conclusion is speculative.

"A critical question of Alzheimer's disease is why certain parts of the brain have diseased nerve cells and other areas of the brain seem fine. This paper speaks to that question."

It remains to be seen whether there's a "real relationship" between the daydreaming part of the brain and Alzheimer's, he said.