Study Identifies Earliest Stages of
Alzheimer’s Disease
Newswise, October 11, 2011—
Addressing the earliest stages of
Alzheimer’s disease, before a patient
shows outward signs of cognitive
problems, has sometimes been a challenge
for physicians and researchers, in part
because they have not been using common
and specific terms to describe the
disease’s initial phases.
A
Mayo Clinic study recommends adding
categories to more effectively identify and treat people
and give researchers standard definitions to work with.
The study is published in this month’s issue of the
Annals of Neurology.
The researchers assessed new
guidelines for preclinical Alzheimer’s disease (AD) that
were recently published by a working group formed by the
National Institute on Aging and the
Alzheimer’s Association (NIA-AA).
The group’s work marked the first
attempt to define criteria for Alzheimer’s preclinical
phase, which is increasingly recognized as a long latent
stage of the disease in which Alzheimer’s pathology and
biomarkers of that pathology become abnormal, while
subjects remain clinically asymptomatic. The guidelines
represented a significant step forward because evidence
increasingly suggests this early phase is the best time
to treat the disease.
The Mayo researchers concluded,
however, that the three stages defined by the workgroup
are not sufficient to describe all cognitively normal
elderly patients. They recommend adding two more groups.
“The important guidelines developed
by the NIA-AA workgroup were a vital step in
clarifying the progression of this
devastating disease and aiding in earlier
diagnosis,” says lead author
Clifford R. Jack, Jr., M.D., a
Mayo Clinic neurologist and the
Alexander Family Professor of Alzheimer’s
Disease Research. “Our study builds on that
work by recommending two additional
sub-groups that merit attention.”
In addition to stages 1, 2 and 3
identified by the NIA-AA workgroup, the authors suggest
two additional categories:
* Stage 0: Patients with normal biomarkers and no
evidence of cognitive impairment. An estimated 43
percent of all cognitively normal elderly people would
be classified as Stage 0.
* SNAP patients: Those with “suspected non-AD
pathophysiology.” Such patients have normal brain
amyloid imaging studies, but abnormal neurodegeneration
biomarkers. An estimated 23 percent of cognitively
normal elderly patients would fall into the SNAP
category.
“Without the additional categories
we recommend, more than half of all preclinical AD
patients would be ‘forced’ into a category that was not
descriptive of their current state,” says co-author
Ronald C. Petersen, M.D., Ph.D., a
neurologist and the Cora Kanow Professor of Alzheimer’s
Disease Research at Mayo Clinic. “By more clearly
defining the stages of preclinical Alzheimer’s disease
and categories of elderly subjects who should not be
classified as preclinical AD, we can improve its
diagnosis and help in the management of this devastating
disease.”
According to the Alzheimer’s
Association, more than 5.4 million Americans have the
disease, and its incidence is on the rise; one American
develops the disease every 69 seconds. Alzheimer’s
destroys brain cells, causing memory, thinking and
behavioral problems severe enough to affect work, family
and social relationships. Eventually, it affects the
most basic activities of daily living, is incurable and,
ultimately, is fatal. Alzheimer’s is the sixth-leading
cause of death in the United States, and the
fifth-leading cause for people 65 and older, association
statistics show.
About Mayo Clinic
Mayo Clinic is a nonprofit worldwide leader in medical
care, research and education for people from all walks
of life. For more information, visit
www.mayoclinic.org/about/ and
www.mayoclinic.org/news.
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