Radiologists identify early brain marker of Alzheimer's disease

Sep 25, 2007

Researchers using functional magnetic resonance imaging (fMRI) have found a new marker which may aid in early diagnosis of Alzheimer’s disease, according to a study published in the October issue of Radiology.

“The findings of this study implicate a potential functional, rather than structural, brain marker—separate from atrophy—that may help enhance diagnosis and treatment monitoring of Alzheimer’s patients,” said the study’s lead author, Jeffrey R. Petrella, M.D., associate professor of radiology at Duke University Medical Center in Durham, N.C.

Alzheimer’s disease is a progressive brain disorder characterized by memory loss, confusion, personality or behavioral changes and other symptoms. According to the Alzheimer’s Association, more than five million Americans currently have Alzheimer’s disease.

While there is still no cure for the disorder, early diagnosis is crucial so that the patient receives proper treatment.

“As new therapies for Alzheimer’s disease enter the pipeline over the next five years, early diagnosis will become critical for patient selection,” Dr. Petrella said. “fMRI may play a key role in early diagnosis, when combined with clinical, genetic and other imaging markers.”

Among the earliest known changes to the brain in Alzheimer’s disease are episodic memory deficits and structural changes in the medial temporal lobe (MTL). For the study, Dr. Petrella and colleagues set out to identify brain regions in which changes in activation took place during a memory task and to correlate these changes with the degree of memory impairment present in patients with Alzheimer’s disease or mild cognitive impairment.

The researchers studied 13 patients with mild Alzheimer’s disease, 34 patients with mild cognitive impairment and 28 healthy controls. The study group contained 37 men and 38 women with a mean age of 72.9 years. After completing standard neuropsychological testing, the study participants were monitored with fMRI while performing a face-name associative memory task.

While some areas of the brain activate, or turn on their activity, when a person tries to remember something, other areas deactivate, or suppress their activity. Results from this study showed that along the spectrum from healthy people at low risk, to people with mild memory problems, to patients with Alzheimer’s disease, there was increasingly impaired activation in the MTL, an area of the brain associated with episodic memory that normally turns on during a memory task. More surprising, however, was increasingly impaired deactivation in the posteromedial cortices (PMC), an area recently implicated with personal memory that normally suppresses its activity during a memory task. The magnitude of deactivation in the PMC was closely related to the level of memory impairment in the patients and significantly correlated with their neuropsychological testing scores.

While previous studies have suggested that MTL activation may be a possible marker of Alzheimer’s, based on the findings, Dr. Petrella and colleagues concluded that, compared to activation in the MTL, deactivation in the PMC may represent a more sensitive marker of early Alzheimer’s disease.

“In other words, the brain not only loses its ability to turn on in certain regions, but also loses its ability to turn off in other regions, and the latter may be a more sensitive marker. These findings give us insight into how the brain’s memory networks break down, remodel and finally fail as memory impairment ensues,” Dr. Petrella said.

The researchers hope that fMRI will eventually help to identify patients at risk for developing Alzheimer’s disease.

The next step is to conduct a large, multicenter study to see if fMRI can be combined with other imaging and genetic tests to scan for future disease,” said study co-author P. Murali Doraiswamy, M.D., chief of the Division of Biological Psychiatry and Alzheimer’s clinical trial expert at Duke. “Much like a negative colonoscopy gives you reassurance, a normal fMRI may, in the future, also offer predictive value.”

Source: Radiological Society of North America

Explore further: Second bird flu case confirmed in Canada

add to favorites email to friend print save as pdf

Related Stories

Frenchman Tirole wins Nobel economics prize

Oct 13, 2014

(AP)—French economist Jean Tirole won the Nobel prize for economics Monday for research on market regulation that has helped policymakers understand how to deal with industries dominated by a few companies.

The 2014 Nobel Prizes at a glance

Oct 13, 2014

(AP)—All winners of the 2014 Nobel Prizes have now been announced, starting with the medicine award a week ago and ending with the economics prize on Monday.

Modiano wins Nobel for works about Nazi occupation

Oct 09, 2014

Patrick Modiano of France, who has made a lifelong study of the Nazi occupation and its effects on his country, won the 2014 Nobel Prize in literature Thursday for what one academic called "crystal clear ...

Recommended for you

Ebola reveals shortcomings of African solidarity

16 hours ago

As Africa's leaders meet in Ethiopia to discuss the Ebola crisis, expectations of firm action will be tempered by criticism over the continent's poor record in the early stages of the epidemic.

Second bird flu case confirmed in Canada

Jan 30, 2015

The husband of a Canadian who was diagnosed earlier this week with bird flu after returning from a trip to China has also tested positive for the virus, health officials said Friday.

What exactly is coronavirus?

Jan 30, 2015

The conflicts in Syria and Iraq are straining public health systems and public health efforts meant to prevent and detect the spread of infectious diseases. This is generating a "perfect storm" of conditions for outbreaks. Among the infections raising concern is Middle East Respiratory Syndrome, caused by a type of coronavirus, which emerged in 2012. ...

Scientists find Ebola virus is mutating

Jan 30, 2015

(Medical Xpress)—Researchers working at Institut Pasteur in France have found that the Ebola virus is mutating "a lot" causing concern in the African countries where the virus has killed over eight thous ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.