Improving Alzheimer's Diagnosis
Proposal: Use High-Tech Alzheimer's Tests for Earlier Diagnosis
July 9, 2007 -- It's time to change the way doctors diagnose Alzheimer's disease, says an international panel of experts.
Despite more than two decades of scientific advances in understanding Alzheimer's disease, doctors are still stuck in 1984. That's when a U.S. National Institutes of Health working group came up with the clinical criteria for a formal diagnosis of Alzheimer's disease.
It's time for radical change, argue Bruno Dubois, MD, of Salpêtrière Hospital, Paris, and 18 other leading Alzheimer's experts.
The old criteria "have now fallen behind the unprecedented growth of scientific knowledge," Dubois and colleagues write in the August issue of The Lancet Neurology.
That's true, says Norman Foster, MD, director of the Center for Alzheimer's Care, Imaging, and Research at the University of Utah, Salt Lake City. Foster's editorial accompanies the paper by Dubois and colleagues.
"We now are seeing the potential to disrupt the basic development of Alzheimer's disease with medications," Foster tells WebMD. "So we want early diagnosis and early intervention. The current criteria get in the way of this."
High-Tech Alzheimer's Diagnosis
People are said to have probable Alzheimer's disease if they have two clinical signs: a memory disorder and impairment of at least one other mental function. For an Alzheimer's diagnosis, both these problems must interfere with social function or the activities of daily living.
That was a big breakthrough 25 years ago. Since then, doctors have learned that several other conditions cause the same impairments. Yet with an emphasis on earlier treatment, there's pressure on doctors to diagnose Alzheimer's disease as early as possible.
"We are caught between a rock and a hard place as clinicians," Foster says. "We cannot distinguish accurately when mild cognitive impairment represents Alzheimer's disease, when it represents some other significant illness, or when it is just a passing problem."
Dubois and colleagues propose using a new formula. To get an Alzheimer's diagnosis, a person would first have to suffer memory loss that gets worse over a six-month period. That person would also have to have at least one physical "biomarker" of Alzheimer's disease:
- An MRI scan showing shrinking of a particular part of the brain
- Abnormal proteins -- beta-amyloid or tau tangles -- in the cerebrospinal fluid
- A PET scan showing patterns of brain activity linked to Alzheimer's disease
- A genetic mutation linked to Alzheimer's disease