MANHASSET, NY — Scientists have been testing a number of biomarkers, including regional brain volumes, cerebrospinal fluid (CSF) measures of pathological proteins and cognitive measures and a new study putting these markers to the test in one of the largest biomarker studies to date – the Alzheimer’s Disease Neuroimaging Initiative (ADNI) – suggests that testing a person’s ability to delay verbal memory is one of the strongest predictors that a person is on the road to Alzheimer’s or is already there.
“Many scientists have looked at specific biomarkers in isolation but never set up a study to compare them head-to-head,” said Terry E. Goldberg, PhD, an investigator at the Feinstein Institute for Medical Research and professor of psychiatry and behavioral science at Hofstra North Shore-LIJ School of Medicine. “We took an unbiased approach and measured the predictive value of each biomarker. The cognitive markers were better predictors of conversion to Alzheimer’s disease than CSF biomarkers and structural imaging.
The study is published in the September issue of the Archives of General Psychiatry.
ADNI is a longitudinal multi-center observational study sponsored by the National Institutes of Health that was initiated to understand the progression from mild cognitive impairment to Alzheimer’s disease. They used a number of biomarkers and clinical and neurocognitive measures. Data from the ADNI project is public so that scientists can do their own analyses of the information that is collected. And that is precisely what Dr. Goldberg and his colleagues did. They studied records from patients who had completed at least two visits over the two-year study period and a subsequent exam. There were 204 MCI patients who had not converted to Alzheimer’s during the two-year study window and 116 who had been handed a diagnosis of Alzheimer’s. They also had data on 197 cognitively normal older people.
Patients were asked to take a number of cognitive tests and measures of global functioning. In addition, the ADNI study conducted biomarker studies and that information was used to understand the best predictors of conversion to MCI. They reported that the cognitive measures were more predictive than the biomarkers. The reason, said Dr. Goldberg, “is that there is not a lot of neurobiological differences in the brains of people with MCI and AD.”
Mild Cognitive Impairment, or MCI, is a judgment call on the part of a clinician. The pathogenesis of Alzheimer’s may start a decade or more before symptoms develop “so that it makes sense that the biomarkers may be more stable than the changes on cognitive tests. Presenting patients with a word list and asking them 30 minutes later to recall words on the list is a classic test for dementia.
When they analyzed two different time points in the same patients they found that changes in measures of cognitive speed were important predictors as well as changes in functional activity.
“Cognitive measures should not be left out of the research equation,” said Dr. Goldberg. “They work at predicting Alzheimer’s.”
About The Feinstein Institute for Medical Research Headquartered in Manhasset, NY, The Feinstein Institute for Medical Research is home to international scientific leaders in Parkinson’s disease, Alzheimer’s disease, psychiatric disorders, rheumatoid arthritis, lupus, sepsis, inflammatory bowel disease, diabetes, human genetics, leukemia, lymphoma, neuroimmunology, and medicinal chemistry. The Feinstein Institute, part of the North Shore-LIJ Health System, ranks in the top 6th percentile of all National Institutes of Health grants awarded to research centers. For more information: www.FeinsteinInstitute.org