Brain scans using positron emission tomography, or PET, markedly increase the ability of doctors to predict which patients will develop Alzheimer's disease as they grow older.That's the main finding from the first large study to assess the use of PET scans in older people who complain of mild memory problems.
Alzheimer's disease is a growing health problem, impacting about 4 million people in the United States. Optimal treatment depends on catching the disease in its earliest stages, but that has proved difficult. However, recent research suggests Alzheimer's affects metabolism of glucose in the brain, and PET scans are capable of detecting this effect. That might make PET scans useful in uncovering early disease.
Researchers from UCLA began screening patients who reported mild cognitive problems with PET in the early 1990s. The patients' neurologists first predicted the progression of the disease without seeing the PET scans, then again after seeing the scans. Patients were followed for two to 10 years to assess their progress.
Results showed adding a PET scan improved the ability of neurologists to accurately predict future problems by as much as 30 percent. For example, clinical assessments led neurologists to correctly diagnose their patients as free of progressive dementia 66 percent of the time. When a negative PET scan was added to the mix, that figure jumped to 96 percent. Similar results were seen for patients with positive PET scans. Eighty-four percent of neurologists correctly predicted progression of the disease without a PET scan, rising to 94 percent when a PET scan was available.
Overall, patients with positive PET scans were over 18-times more likely to experience progressive disease as those with negative PET scans. Study author Dr. Dan Silverman, comments, "Adding PET to the diagnostic evaluation of patients with mild cognitive changes can improve our accuracy in predicting what will happen to them in the future -- and enhance our ability to intervene earlier."