Early results from Alzheimer's neuroimaging studies could speed research

Disease 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.

Preliminary results from ADNI show how it might yield improved methods and uniform standards for imaging and biomarker analysis, so these techniques can be employed in the fight against Alzheimer's disease.

These first findings were presented at the Alzheimer's Association International Conference on the Prevention of Dementia.

The ADNI study observes and tracks changes in normal individuals, in people with mild cognitive impairment, a condition which often precedes Alzheimer's, and in people with Alzheimer's. Researchers will use PET (positron emission tomography) and MRI (magnetic resonance imaging) scans to track changes in the brain, laboratory analyses of cerebrospinal fluid and blood to study biomarkers, and clinical interviews to track cognitive performance over time. ADNI is expected to improve neuroimaging and biomarker measures and consequently allow faster and more efficient evaluation of potential therapies for Alzheimer's.

The $60 million, five-year study began recruiting in early 2006, and today about 800 older people at 58 sites in the United States and Canada participate in the effort. The project is supported primarily by the National Institute on Aging (NIA), a component of NIH, with private sector support from pharmaceutical companies, other organizations and the Alzheimer's Association 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 Food and Drug Administration.

"New treatment options are urgently needed for the millions of people who have Alzheimer's and for those at risk as the population ages," says Richard J. Hodes, M.D., Director of the NIA. "This preliminary report on aspects of ADNI is quite encouraging."

ADNI principal investigator Michael Weiner, M.D., of the Department of Veterans Affairs Medical Center, University of California, San Francisco, is scheduled to give a progress report and describe the new ADNI database during the conference. Nine other ADNI researchers will also give reports on early results and preliminary findings from various studies including:

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 mild cognitive impairment over a six month period. Further study, the researchers said, would be needed to see if the changes, with other brain measures, could predict conversion from mild cognitive impairment to Alzheimer's.

Validating PET scans, A study reported by scientists at the Banner Alzheimer's Institute, Phoenix, Ariz., and colleagues compared changes over time in PET scans of glucose metabolism in people with normal cognition, mild cognitive impairment and Alzheimer's. The study found that scans correlated with symptoms of each condition and that images from different clinical sites were comparable (or consistent). This study suggests the validity of PET scans for use in future clinical trials.

MRI Reliability, A Mayo Clinic, Rochester, Minn., study found that a standard anatomical model of a brain can be used successfully to monitor performance of MRI scanners at many different clinical sites. This will ensure accuracy of the MRI images produced from ADNI volunteers using 80 MRI scanners from scores of sites over five years.

Biomarker Analysis, University of Pennsylvania, Philadelphia, scientists and colleagues compared analyses of cerebrospinal fluid samples among seven laboratories. The study evaluated differences within and among the labs, performance. This study will ensure that methods for measuring biomarkers are accurate and comparable across laboratories.

An important achievement of ADNI is the creation of a publicly accessible database available to qualified researchers worldwide. The database contains thousands of MRI and PET scan brain images and clinical data and will include biomarker data obtained through blood and cerebrospinal fluid analyses. ADNI includes samples and brain scans from 200 people with Alzheimer's, 400 people with mild cognitive impairment and 200 healthy people. All volunteers are between ages 55 and 90. Confidentiality of the participants is rigorously protected.

"The database gives ADNI researchers easy access to a huge body of data. But its added value is its design as an international research resource, available worldwide to other researchers interested in neurodegenerative disease," says Susan Molchan, M.D., NIA's program director for ADNI.