A Timeline for Alzheimer’s Disease?

Alzheimer's disease brain changes may appear long before cognitive symptoms

(RxWiki News) Recent research found that changes in the brain and body may begin years before symptoms of Alzheimer’s disease (AD) begin.

The signs of early onset AD may show as early as 25 years before symptoms begin.

Understanding the timing of the early signs of AD may help doctors to provide better treatment.

"Talk to your doctor about any memory problems."

Researchers, led by Randall J. Bateman, MD, of Washington University School of Medicine in St. Louis, looked at proteins in people who were at risk for developing early onset AD.

Early onset AD is rarer than later onset forms of the disease. Its symptoms begin when a person is 30 to 40 years old.  This form of AD is linked to certain genetic factors, passed down from parents.

Dr. Bateman’s study used results of cognitive tests, brain scans, blood tests and spinal fluid tests to look at early signs of AD in patients who had a parent with early onset AD. An age of expected onset was calculated by looking at the parent’s age of onset.

They found that beta amyloid, a protein that builds up in the brain in AD, was decreased in the spinal fluid 25 years before the expected onset of symptoms.

A positron emission tomography (PET) scan, a way to image the brain, showed that beta amyloid plagues and signs of brain damage were present 15 years before symptoms were expected to begin.

Early signs of mental difficulties showed up between 5 and 10 years before the expected onset of symptoms.

The authors concluded that early onset AD follows a path of slow progression, just as in late onset AD.  In both, early signs of the disease are present, and understanding the early signs will help improve treatment outcomes.

These types of tests and scans are not currently available to most people because they are costly. Also, it is not yet clear what types of results on these tests will clearly indicate AD, so more research is needed.

The report was published July 11 in the New England Journal of Medicine.  Authors on this study report financial affiliations with AstraZeneca, Novartis, Pfizer, Bayer, Abbot, Bristol-Meyers Squibb, Merck, among other pharmaceutical and biotechnology companies.

Review Date: 
July 11, 2012