Late and early onset Alzheimer's affect brain function in similar way

Date: Sep-01-2014Uninherited Alzheimer's disease is a common form that usually affects older people,

whereas the much rarer, inherited form - also known as early onset Alzheimer's - strikes people

much earlier in life, sometimes as young as 30 or 40. Now, a new study led by Washington

University in St. Louis, MO, finds there are networks in the brain that are affected in a similar

way by both forms of the disease.

Reporting the findings in the journal JAMA Neurology, the international team

suggests that in both inherited and uninherited forms of Alzheimer's, the same basic component

of brain function begins to decline about 5 years before symptoms such as memory loss become

obvious.

Senior author Beau Ances, associate professor of neurology at Washington University's School of

Medicine, says:

"The brain networks affected by inherited Alzheimer's disease in a 30-year-old are very

similar to the networks affected by uninherited Alzheimer's disease in a 60-, 70- or 80-year-old. This affirms that what we learn by studying inherited Alzheimer's, which appears at younger

ages, will help us better understand and treat more common forms of the disease."

Functional connectivity breaks down in similar way in early and late-onset Alzheimer's

The feature that the team says breaks down in both forms of the disease is what is termed

"functional connectivity," where the activity levels of networked brain regions rise and fall in

step with each other. Scientists believe this type of coordination helps brain regions work

together, and also to stay out of each other's way, during mental activity.

The researchers say checking functional connectivity in the brain could be a way to monitor how Alzheimer's treatments are working as the disease progresses.

Prof. Ances says checking functional connectivity could be a useful way to monitor how

treatments are working as the disease moves from the early stages to the emergence of more

obvious symptoms:

"Right now, this period when functional connectivity begins breaking down is a time when

family and loved ones may start noticing little changes in personality or mental function in

someone with the disease, but not significant enough changes to cause real alarm," he

explains.

The team hopes in the future it will be possible to ensure treatment has begun well in

advance of these types of changes, "we want to slow or stop the damage caused by Alzheimer's

years earlier," Prof. Ances says.

Scientists have already established that some of the proteins that become problematic in

early onset Alzheimer's also cause problems in the more common form that usually appears in

older people.

Finding enough data is a challenge in researching both forms of Alzheimer's

They also believe there are more similarities between the two forms of the disease, but it is

not an easy subject to research, hampered by two challenges in particular: finding enough people

with inherited Alzheimer's to study, and the fact both forms of the disease progress slowly.

With the first challenge in mind, Washington University's Charles F. and Joanne Knight

Alzheimer's Disease Research Center started an international network for studying families with

inherited, early onset Alzheimer's disease. Set up 5 years ago, the Dominantly Inherited

Alzheimer's Network, or DIAN, has now enrolled nearly 400 families.

To meet the second challenge, the research center has also been collecting extensive data

from long-term studies of aging, such as the Healthy Aging and Senile Dementia Study, which has

been going for over 30 years.

Brain scan data from these two initiatives has been sufficient to allow the study authors to

compare functional connectivity in the two forms of Alzheimer's disease. To study functional

connectivity, researchers need the results of brain scans taken as participants daydream.

Functional connectivity may help keep track of disease progression in diagnosed

patients

Prof. Ances says they found the decline of functional connectivity appears to play a role in

the middle stages of Alzheimer's disease. But that is not where you want to look for an initial

diagnosis, because you want to treat the disease before it gets to that stage.

So while the findings may not help with early diagnosis, what they suggest, says Prof. Ances,

is that "functional connectivity may help us track the progression of Alzheimer's in patients who are

first diagnosed when they're beginning to show early signs of dementia."

Meanwhile, from another recently published study by researchers in Australia, Medical

News Today learned how some
areas of the brain may not slow down with aging, but remain as effective as they are in

youth.

Written by Catharine Paddock PhD

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Courtesy: Medical News Today Note: Any medical information available in this news section is not intended as a substitute for informed medical advice and you should not take any action before consulting with a health care professional.