New Alzheimer's Guidelines Stress Early Diagnosis
Spinal Fluid, Imaging Tests Still Experimental but May Confirm Early Alzheimer's
Biomarkers for Alzheimer's Disease
Biomarkers are tests that detect a disease process. Examples are tests of cholesterol levels to predict heart disease risk or blood sugar tests to predict diabetes.
Biomarkers are being developed for Alzheimer's disease, but the guidelines stress that they are not yet ready for clinical use except in certain well-defined situations.
There are several Alzheimer's biomarkers being explored, but two basic types are in the most advanced stages of development:
- Cerebrospinal fluid (CSF) test. A protein called beta-amyloid begins to accumulate in the brain even in the early stages of Alzheimer's disease. When this happens, beta-amyloid levels drop in the CSF. Tests of CSF, collected by a spinal tap, measure beta-amyloid levels.
- Imaging tests such as PET scans, SPECT perfusion imaging, and even MRI scans can detect beta-amyloid accumulation or markers of brain injury typical of Alzheimer's disease.
The new guidelines stress that none of these tests have been fully validated and that there are no cutoff levels that clearly distinguish normal people from those who have Alzheimer's.
Nevertheless, the guidelines suggest that for some patients with mild cognitive impairment suggestive of Alzheimer's disease, biomarker tests "would affect levels of certainty in the diagnosis."
Treatment for Alzheimer's Disease
There's no cure for Alzheimer's disease, so why the emphasis on early detection? Kennedy says the earlier you detect possible Alzheimer's, the more you can do about it.
"Ten years ago we said there was no treatment for Alzheimer's. That isn't true now," he says. "We can't cure it, but just like diabetes, we can delay the illness and disability associated with it. I counsel patients to be aggressive about diet and exercise, to take the medications they need for other conditions, and to stay intellectually engaged."
The new Alzheimer's guidelines appear in the April 19 online issue of Alzheimer's & Dementia: The Journal of the Alzheimer's Association.