Using PET imaging can help diagnose Alzheimer's disease earlier while reducing erroneous diagnoses and thereby saving people from months of unnecessary drugs and nursing home care, according to UCLA researchers.

When combined with conventional methods of diagnosis, positron emission tomography (PET) can cut drug therapy by half and reduce the time spent in nursing homes by 60 percent, according to their report in the journal Molecular Imaging and Biology.

"With the introduction of promising new drugs to treat the mildest stages of Alzheimer's disease, diagnosing patients early is more important than ever before," said Dr. Dan Silverman, assistant professor of molecular and medical pharmacology and principal investigator of the study.

"PET boosts the number of Alzheimer's cases that are detected early and can substantially reduce the number of elderly patients falsely diagnosed with Alzheimer's disease," said Silverman.

Researchers studied two strategies for diagnosing Alzheimer's disease to see whether the condition was responsible for early signs of dementia in elderly patients. The first approach followed the American Academy of Neurology's 2001 recommendations for the clinical evaluation of dementia.

The second approach followed the Academy's recommendations but also used PET to measure the brain metabolism of the patient for signs of early damage linked to Alzheimer's disease.

Researchers studied both courses of diagnosis for their range of accuracy in diagnosing Alzheimer's disease and found the differences striking.

"Although both approaches accurately diagnosed most Alzheimer's patients, we found that the appropriate use of PET could reduce erroneous diagnoses by half," reported Silverman.

Researchers looked at current medical literature on Alzheimer's disease diagnosis. For every 100 patients experiencing early cognitive decline, the literature showed that conventional diagnostic methods would have erroneously attributed the patients' symptoms to early Alzheimer's disease in 23 cases and overlooked eight cases of the disease.

Investigators found that incorporating the use of PET in these patients' clinical evaluations would have prevented 11 of the 23 false positives and five of the eight false negatives.

When calculating how much PET would reduce unnecessary nursing home care, researchers estimated that accurate identification of Alzheimer's disease in five percent more patients would diminish placement in nursing homes by at least 45 months for every 100 patients.

Also, in the 11 per 100 people spared from a false diagnosis of Alzheimer's disease, researchers estimated that adding PET to clinical evaluations would prevent more than 130 months per year of needless drug therapy per 100 people.

Overall, the benefit of using PET in diagnosing patients for Alzheimer's disease equated to a 62 percent decrease in avoidable months of nursing home care and a 48 percent drop in unnecessary drug therapy.

"It's worse to diagnose someone with Alzheimer's later than earlier, because we now have drugs available to help delay progression of the disease," said Silverman. "Postponing drug therapy by as little as six months in people with Alzheimer's may have long-term consequences for their cognitive function."

Other sources: UCLA