San Francisco -- If doctors are ever going to find a way to
attack and even cure Alzheimer's disease, they first need to know
how to diagnose it -- ideally years, maybe even decades, before
patients are symptomatic and their brain has been irreparably
damaged.
That's why researchers around the country are intrigued by
several promising new studies that highlight techniques for
identifying Alzheimer's in the body long before people show the
classic signs of memory loss and confusion.
A study that was released in August to much excitement among
researchers suggested that a spinal fluid test could be very
effective in identifying abnormal levels of amyloid, a protein that
forms plaque buildups in the brains of people with Alzheimer's.
In the Bay Area, researchers at the University of California at
San Francisco and Stanford are studying drugs that would serve as
biomarkers in the body, attaching themselves to proteins like
amyloid and letting doctors find those proteins more easily using
imaging tests.
"It's exciting that we will likely soon have new tools that
will allow us to detect Alzheimer's changes very early, even in
people who are cognitively normal," said Dr. Adam Boxer , director
of the Alzheimer's disease and frontotemporal dementia clinical
trials program at UCSF's Memory and Aging Center. "If there were a
treatment that could remove amyloid from the brain, then it would
really be an exciting and powerful combination."
People are currently tested for Alzheimer's using a fairly
lengthy, somewhat subjective process that starts with simple memory
tests and interviews with patients and their family about problems
they may be having from day to day. Those tests are accompanied by
a physical examination, more thorough cognitive testing, and blood
analysis and a brain-imaging scan.
The process is more about ruling out other diseases with similar
symptoms -- such as a stroke or a benign brain tumor -- that may be
easily treated. After the testing is over, doctors can reliably
diagnose Alzheimer's with about 90 percent accuracy, but it can
only be confirmed after death, when brain tissue can be studied
under a microscope.
For patients and the doctors treating them, it's not necessarily
important to definitively diagnose Alzheimer's because for now
there's no cure for the disease. But for researchers, it's
essential to be able to identify test subjects who have been
diagnosed with Alzheimer's so that they can focus on potential
treatments.
Researchers hope that if doctors can find abnormal buildup of
proteins before people become symptomatic, it may be easier to find
effective treatments. Most studies of potential drug treatments for
Alzheimer's have had disappointing results.
"Many (researchers) believe these studies may have failed
because we started treating people too late," Boxer said. "The
majority of people in studies have full-blown Alzheimer's disease,
and it's a tall order to get treatments to work in these people.
It's hoped that by developing biomarkers, we could find it much
earlier."
Most research into early diagnosis of Alzheimer's disease is
centered around two proteins: amyloid beta, which is distinctive
for the way it clumps up in the brain like plaque, and tau, which
forms tangled strands in the brain when neurons die. Buildup of
these proteins is common in the brains of deceased people who had
Alzheimer's.
At Stanford, a team of researchers is participating in a
national study of the drug florbetaben , which would act as a
marker for amyloid and allow doctors to find the protein using
certain imaging techniques. UCSF researchers, meanwhile, are
looking for similar drugs that might be used a biomarkers for the
tau protein.
The spinal fluid test, which was studied primarily at the
University of Pennsylvania, involves performing a spinal tap on
patients to look for signs of both proteins.
Dr. Marci Teresi , clinical lead of the Kaiser Permanente Santa
Clara Memory Clinic, said doctors are enthusiastic about the
current research, but she doesn't expect such testing to be made
widely available outside of research studies any time soon.
"It's mostly useful for investigational purposes, for finding
people who want to participate in research studies," Teresi said.
"I don't think it's as practical for the large number of patients
that are out there seeing their regular doctors."
In other words, patients with no Alzheimer's symptoms shouldn't
start asking their doctors for advanced imaging tests any time
soon. In fact, early testing could do more harm than good, some
doctors say, if it causes patients anxiety and depression before
they're showing signs of Alzheimer's. Some people with protein
buildup in their brains never get Alzheimer's at all.
Still, there are advantages to screening older people who may be
showing the first small signs of illness, said Dr. Catherine
Madison , medical director of California Pacific Medical Center's
Memory Clinic.
Several drugs can make life for patients more comfortable and
slow down some of the worst effects of the disease, especially if
the treatment is started early. Patients can also benefit from
therapy and anti-depressants.
"There's no magic cure out there. Even if I could tell you that
you were going to get dementia, would you want me to?" Madison
said. "But we have medications that can help. We can slow the
course of this and make it a whole lot better for patients and
families."
c.2010 San Francisco Chronicle