Formula Predicts Alzheimer's Longevity
Researchers Develop Method to Predict How Long Alzheimer's Patients Will Live
April 13, 2010 (Toronto) -- "Tell me, doctor, how long do I have?"
That, says Gregory A. Jicha, MD, is the first question patients ask after
receiving a diagnosis of Alzheimer's disease.
Until now, the answer has largely been a guessing game. But Jicha and
colleagues have developed a simple formula based on a patient's sex, age, and
cognitive skills at the time of diagnosis to more accurately predict life
"Having a better of idea of how long they will live will allow patients and
families to better plan for the future," says Jicha, an assistant professor of
neurology at the University of Kentucky in Lexington.
He presented his findings at the annual meeting of the American Academy of
Wide Range of Life Expectancies
Jicha tells WebMD he decided to develop the formula after treating a patient
who lived 22 years from the time of her Alzheimer's diagnosis.
"We typically think of Alzheimer's disease as being rapidly progressing,
telling new patients they may have six to eight years, but that really, it is
in God's hands," he says.
When Jicha and colleagues scrutinized the records of nearly 1,300 men and
women who had been diagnosed with Alzheimer's at their institution, they found
patients lived anywhere from one to 26 years from when they first started
losing their memory.
So the researchers used standard statistical methods to weed out which risk
factors best predicted patients' life expectancies.
"We looked at everything from age and education to family history and
genetics to medical risk factors like high blood pressure and heart disease,"
Only three factors seemed to matter: age at first symptoms (older people die
more quickly), sex (men fare worse), and level of impairment at diagnosis.
Adding in any of the other risk factors didn't change the bottom line, Jicha
Using the three factors, the researchers derived a simple formula to predict
patients' risks of dying. Then, based on these so-called risk scores, the
patients were divided into four categories of life expectancy.
People in the top fourth lived from four and one-half to nine years, or an
average of about seven years, from diagnosis. Those in the bottom fourth lived
from about one year and nine months to five years, or an average of about three
years, Jicha says.
Jicha gave some examples. Based in the formula, an 82-year-old woman with
mild to moderate dementia can be expected to live five years from diagnosis, he
says. A 63-year-old man with mild dementia at diagnosis should survive seven
years, he says.
Help for Alzheimer's Planning
"A two- to four-year difference in survival can be incredibly important for
budgeting resources," Jicha says. "If a patient is going to live longer, you
may want to care for them at home longer. Whereas if we know there will be a
rapid progression of disease, you may want to make plans for a nursing home or
other care facility."
Stephen Salloway, MD, a professor of neurology at Brown University, says
that the fact that the model is science-based gives it some validity.
Still, he tells WebMD, "We’re not at the point where we can be that
specific. You have to couch it a little; tell a patient that 'the majority of
people with your stage of disease and your age might be expected to live five
to seven years,' for example. But I would not give an exact number."
Jicha agrees. "You always need the caveat. This is a best guess