Home  |  Top News  |  Most Popular  |  Video  |  Multimedia  |  News Feeds  |  Feedback
  Medicine  |  Nature & Earth  |  Biology  |  Technology & Engineering  |  Space & Planetary  |  Psychology  |  Physics & Chemistry  |  Economics  |  Archaeology
Top > Medicine, Health Care > Alzheimer's Progression Tracked Prior to… >
Alzheimer's Progression Tracked Prior to Dementia

Published: September 24, 2013.
By Washington University School of Medicine
http://www.medicine.wustl.edu

For years, scientists have attempted to understand how Alzheimer's disease harms the brain before memory loss and dementia are clinically detectable. Most researchers think this preclinical stage, which can last a decade or more before symptoms appear, is the critical phase when the disease might be controlled or stopped, possibly preventing the failure of memory and thinking abilities in the first place.

Important progress in this effort is reported in October in Lancet Neurology. Scientists at the Charles F. and Joanne Knight Alzheimer Disease Research Center at Washington University School of Medicine in St. Louis, working in collaboration with investigators at the University of Maastricht in the Netherlands, helped to validate a proposed new system for identifying and classifying individuals with preclinical Alzheimer's disease.

Their findings indicate that preclinical Alzheimer's disease can be detected during a person's life, is common in cognitively normal elderly people and is associated with future mental decline and mortality. According to the scientists, this suggests that preclinical Alzheimer's disease could be an important target for therapeutic intervention.

A panel of Alzheimer's experts, convened by the National Institute on Aging in association with the Alzheimer's Association, proposed the classification system two years ago. It is based on earlier efforts to define and track biomarker changes during preclinical disease.

According to the Washington University researchers, the new findings offer reason for encouragement, showing, for example, that the system can help predict which cognitively normal individuals will develop symptoms of Alzheimer's and how rapidly their brain function will decline. But they also highlight additional questions that must be answered before the classification system can be adapted for use in clinical care.

"For new treatments, knowing where individuals are on the path to Alzheimer's dementia will help us improve the design and assessment of clinical trials," said senior author Anne Fagan, PhD, research professor of neurology. "There are many steps left before we can apply this system in the clinic, including standardizing how we gather and assess data in individuals, and determining which of our indicators of preclinical disease are the most accurate. But the research data are compelling and very encouraging."

The classification system divides preclinical Alzheimer's into three stages:

Stage 1: Levels of amyloid beta, a protein fragment produced by the brain, begin to fall in the spinal fluid. This indicates that the substance is beginning to form plaques in the brain.

Stage 2: Levels of tau protein start to rise in the spinal fluid, indicating that brain cells are beginning to die. Amyloid beta levels are still abnormal and may continue to fall.

Stage 3: In the presence of abnormal amyloid and tau biomarker levels, subtle cognitive changes can be detected by neuropsychological testing. By themselves, these changes cannot establish a clinical diagnosis of dementia.

The researchers applied these criteria to research participants studied from 1998 through 2011 at the Knight Alzheimer Disease Research Center. The center annually collects extensive cognitive, biomarker and other health data on normal and cognitively impaired volunteers for use in Alzheimer's studies.

The scientists analyzed information on 311 individuals age 65 or older who were cognitively normal when first evaluated. Each participant was evaluated annually at the center at least twice; the participant in this study with the most data had been followed for 15 years.

At the initial testing, 41 percent of the participants had no indicators of Alzheimer's disease (stage 0); 15 percent were in stage 1 of preclinical disease; 12 percent were in stage 2; and 4 percent were in stage 3. The remaining participants were classified as having cognitive impairments caused by conditions other than Alzheimer's (23 percent) or did not meet any of the proposed criteria (5 percent).

"A total of 31 percent of our participants had preclinical disease," said Fagan. "This percentage matches findings from autopsy studies of the brains of older individuals, which have shown that about 30 percent of people who were cognitively normal had preclinical Alzheimer's pathology in their brain."

Scientists believe the rate of cognitive decline increases as people move through the stages of preclinical Alzheimer's. The new data support this idea. Five years after their initial evaluation, 11 percent of the stage 1 group, 26 percent of the stage 2 group, and 52 percent of the stage 3 group had been diagnosed with symptomatic Alzheimer's.

Individuals with preclinical Alzheimer's disease were six times more likely to die over the next decade than older adults without preclinical Alzheimer's disease, but researchers don't know why.

"Risk factors for Alzheimer's disease might also be associated with other life-threatening illnesses," Fagan said. "It's also possible that the presence of Alzheimer's hampers the diagnosis and treatment of other conditions or contributes to health problems elsewhere in the body. We don't have enough data yet to say, but it's an issue we're continuing to investigate."


Show Reference »


Translate this page: Chinese French German Italian Japanese Korean Portuguese Russian Spanish


Disclaimer: The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the ScienceNewsline.
Related »

Public 
7/20/11 
International Survey Highlights Great Public Desire to Seek Early Diagnosis of Alzheimer's
By Harvard School of Public Health
Results of an international surveyi reveal that over 85% of respondents in the five countries surveyed say that if they were exhibiting confusion and memory loss, they would want …
Disease 
11/6/13 
'Path to 2025' Alzheimer's Disease Summit: Reforms Urgently Needed to Streamline Road to Alzheimer's
By New York Academy of Sciences
NEW YORK, November 6, 2013 – As the burden of Alzheimer's disease escalates worldwide, efforts to develop effective treatments are failing to keep pace because of the high costs …
Rates 
9/4/13 
Better Hygiene in Wealthy Nations May Increase Alzheimer's Risk
By University of Cambridge
New research has found a "very significant" relationship between a nation's wealth and hygiene and the Alzheimer's "burden" on its population. High-income, highly industrialised countries with large urban areas …
Disease 
7/5/10 
Depression Symptoms Show Little Change During the Development And Progression of Alzheimer's Disease
By Rush University Medical Center
Depression is commonly reported in people with Alzheimer's disease and its precursor, mild cognitive impairment, with several studies suggesting having a history of major depression may nearly double your …
Disease 
4/20/11 
Alzheimer's Diagnostic Guidelines Updated for First Time in Decades
By National Institute on Aging
For the first time in 27 years, clinical diagnostic criteria for Alzheimer's disease dementia have been revised, and research guidelines for earlier stages of the disease have been characterized …
Alzheimer 
12/13/10 
High Levels of 'Good' Cholesterol May Be Associated with Lower Risk of Alzheimer's Disease
By JAMA and Archives Journals
High levels of high-density lipoprotein (HDL), also known as "good" cholesterol, appear to be associated with a reduced risk for Alzheimer's disease in older adults, according to a report …
Alzheimer 
7/10/13 
Penn Study Shows Vascular Link in Alzheimer's Disease with Cognition
By University of Pennsylvania School of Medicine
PHILADELPHIA – Researchers in the Perelman School of Medicine at the University of Pennsylvania found that, across a variety of neurodegenerative diseases, cerebrovascular disease affecting circulation of blood in …
Disease 
2/28/11 
More Evidence That Alzheimer's Disease May Be Inherited from Your Mother
By American Academy of Neurology
ST. PAUL, Minn. – Results from a new study contribute to growing evidence that if one of your parents has Alzheimer's disease, the chances of inheriting it from your …
Disease 
9/16/11 
Safeguards Needed to Prevent Discrimination of Early Alzheimer's Patients in the Workplace
By University of Pennsylvania School of Medicine
PHILADELPHIA - The changing tide of Alzheimer's diagnosis presents new challenges to the public, physicians and lawmakers: if you could find out your Alzheimer's risk, would you want to …
Family 
4/17/13 
Family History of Alzheimer's Associated with Abnormal Brain Pathology
By Duke University Medical Center
DURHAM, N.C. -- Close family members of people with Alzheimer's disease are more than twice as likely as those without a family history to develop silent buildup of brain …
Disease 
9/13/10 
Protein-based Biomarkers in Blood Serum Could Classify Individuals with Alzheimer's Disease
By JAMA and Archives Journals
An initial analysis suggests that biomarkers in blood serum can be combined with clinical information to accurately classify patients with Alzheimer's disease, according to a report in the September …
Disease 
11/10/11 
Requests for Alzheimer's Disease Research Grants Up by 33 Percent, as Federal Funding in Doubt
By AHAF-American Health Assistance Foundation
The American Health Assistance Foundation (AHAF), a nonprofit organization funding innovative research through its Alzheimer's Disease Research (ADR) program, today announced that the number of scientists seeking ADR research …
More » 

Most Popular - Medicine »
GENES »
Loss of Memory in Alzheimer's Mice Models Reversed Through Gene Therapy
TUMORS »
The Immune System's Redesigned Role in Fighting Cancerous Tumors
LOS ANGELES (March 11, 2014) – Researchers in the Cedars-Sinai Samuel Oschin Comprehensive Cancer Institute eradicated solid tumors in laboratory mice using a novel combination of two targeted agents. …
MUTATIONS »
Applying Math to Biology: Software Identifies Disease-causing Mutations in Undiagnosed Illnesses
(SALT LAKE CITY)–A computational tool developed at the University of Utah (U of U) has successfully identified diseases with unknown gene mutations in three separate cases, U of U …
IRON »
Study: Iron Consumption Can Increase Risk for Heart Disease
WHOOPING »
Impact of Whooping Cough Vaccination Revealed
The most comprehensive study to date of the family of bacteria that causes whooping cough points to more effective vaccine strategies and reveals surprising findings about the bacteria's origin …
ScienceNewsline  |  About  |  Privacy Policy  |  Feedback  |  Mobile  |  Japanese
The selection and placement of stories are determined automatically by a computer program. All contents are copyright of their owners except U.S. Government works. U.S. Government works are assumed to be in the public domain unless otherwise noted. Everything else copyright ScienceNewsline.