Researchers may be able to reduce the time and expense associated with clinical trials, according to early results from the Alzheimer's Disease Neuroimaging Initiative (ADNI), a public-private research partnership organized by the National Institutes of Health. ADNI researchers are using serial magnetic resonance imaging (MRI); positron emission tomography (PET) scans; measurement of various biological compounds in blood, cerebrospinal fluid, and urine; and clinical and neuropsychological assessments to track mild cognitive impairment (MCI) and early AD progression.
ADNI researchers will compare neuroimaging, biological, and clinical information from the participants, looking for correlations among the data to develop standards for tracking the progression of memory decline.
An important feature of ADNI is that data will be available to all qualified researchers via password- protected databases on the Web. To date, more than 200 qualified researchers have signed up for database access.
Preliminary results were reported by scientists in June at the Alzheimer's Disease Prevention Conference in Washington, DC. Among the findings:
Predicting Alzheimer's—A University of California, San Diego, study found that analyses of MRI and PET images could detect early changes in cerebral cortex thickness in brains of people with MCI over a 6-month period. Further research is needed to see if the changes, with other brain measures, could predict conversion from MCI to AD.
Validating PET Scans—A study reported by scientists at the Banner Alzheimer's Institute in Phoenix and colleagues compared changes over time in PET scans of glucose metabolism in people with normal cognition, MCI, and AD. The study found that scans correlated with clinical symptoms of each condition and that images from different study sites were comparable (or consistent). This study suggests the validity of PET scans for use in future clinical trials.
MRI Reliability—Mayo Clinic scientists found that a standard physical model can be used successfully to monitor performance of MRI scanners at many different clinical sites. This will help ensure accuracy of the MRI images produced from 80 MRI scanners from scores of sites over 5 years.
Biomarker Analysis—University of Pennsylvania scientists and colleagues compared analyses of cerebrospinal fluid samples among seven laboratories. The study evaluated differences within and among the labs' performance. This will help ensure that methods for measuring biomarkers are accurate and comparable across laboratories.
Significant progress was made in enrolling ADNI participants. Goals were met months ahead of schedule, and enrollment is now complete with a full 798 qualified participants. Of those, 229 have no memory problems, 386 have MCI, and 183 have AD. Investigators recruited participants at 58 local study sites across the U.S. and Canada.
Earlier this year an optional "add-on" component of ADNI was launched, funded by the Alzheimer's Association and General Electric. The project will utilize Pittsburgh Compound B, or "PIB," which is a PET tracer for amyloid imaging, to detect beta-amyloid in the brain. The ability to pinpoint amyloid deposits in the living brain can advance the study of AD and could aid in early, perhaps even preclinical, diagnosis.
The $60 million, 5-year ADNI study is supported primarily by the NIH , with private-sector support from pharmaceutical companies and other private organizations through the Foundation for NIH. In addition to NIA, other Federal partners are the National Institute of Biomedical Imaging and Bioengineering , also part of NIH, and the U.S. Food and Drug Administration . For more information on ADNI, go to www.adni-info.org .