The government today announced its participation in one of the largest initiatives to date to determine effective neuroimaging techniques that will help chart brain changes associated with mild cognitive impairment and Alzheimer's disease. The announcement comes barely two weeks after Medicare agreed to reimburse for PET studies of suspected Alzheimer's patients.
The Alzheimer's Disease Neuroimaging Initiative (ADNI), a five-year $60 million project under the auspices of the National Institute on Aging, seeks to determine what significance serial MR imaging, FDG-PET scanning, other biological markers, and clinical and neuropsychological assessment — either alone or in combination — have in detecting mild cognitive impairment (MCI) and Alzheimer's disease.
The study could help researchers and clinicians develop new treatments and monitor their effectiveness as well as lessen the time and cost of clinical trials, according to the NIA.
Recent research has suggested that hippocampal atrophy, as measured by serial MRI, is a good predictor of future cognitive decline that may lead to AD, in particular, and dementia, in general, said Norbert Schuff, Ph.D., an associate professor of radiology at the Veterans Affairs Medical Center in San Francisco.
Research has also confirmed the high sensitivity of PET to determine the liklihood of someone having AD depending on specific patterns of hypometabolism. Many researchers believe that PET or MR may serve as a more sensitive and consistent measure of disease progression than the neuropsychological and cognitive assessments now typically used in research and clinical practice.
"The weakness of PET is that there are no longitudinal studies comparing it to MRI, which has had longitudinal studies for years. The trial will be the first to use serial FDG-PET scans," said Dr. Norman L. Foster, a professor of neurology at the University of Michigan who will oversee PET quality control and analysis for ADNI.
The initiative also will seek to identify additional biological factors from blood, cerebrospinal fluid, and urine samples.
The study will take place at approximately 50 sites across the U.S. and Canada. Recruitment will begin next April. Investigators want to study about 800 subjects aged 55 to 90:
- approximately 200 cognitively normal subjects to be followed for three years
- 400 people with MCI to be followed for three years
- 200 people with early AD to be followed for two years
About two-thirds of the funding is expected to come from the federal government including the NIA, the National Institute of Biomedical Imaging and Bioengineering, and the FDA. Other funding will come from private partners, including Pfizer, Wyeth, Eli Lilly, Merck, and the Alzheimer's Association.
The key challenge is to identify markers that respond to treatments aimed at slowing the progression of MCI and AD, according to principal investigator Dr. Michael W. Weiner, director of the Magnetic Resonance Unit at the VA Medical Center in San Francisco.
"For example, imaging is used to rule out other causes of memory problems, still not leaving the researcher or the clinician with a very clear idea of what is going on. By the end of this study, we should be able to use imaging and other biomarkers to accurately monitor disease progression and detect the effects of treatments that can slow that progression," he said.
For more information from the Diagnostic Imaging archives:
Medicare begins PET reimbursement for segment of Alzheimer's population
PET, SPECT tracers helps characterize dementias
