Measuring Brain Metabolism Can Predict Progress of Alzheimer's Disease
Metabolic studies may lead to simple blood test (Nov. 7)
Researchers at Tel Aviv University say that early clues regarding the progression of Alzheimer’s disease (AD) can be found in the brain's metabolism.
In very early stages of the disease — before any symptoms appear — metabolic processes are already beginning to change in the brain, says PhD candidate Shiri Stempler. Stempler and colleagues have developed predictor models that use metabolic information to pinpoint the progression of AD. These models were 90% accurate in predicting the stage of the disease.
The new research, published in Neurobiology of Aging, is the first step towards identifying biomarkers that may ensure better detection and analysis of AD at an early stage — all with a simple blood test. It could also lead to novel therapies, Stempler says.
Based on the number of metabolic genes found in neurons and surrounding tissue, the researchers built a predictive model that relates abnormalities in these genes to the progression of AD. Out of almost 1,500 genes, the researchers selected 50 genes that were the most predictive of the disease, Stempler says, noting that these genes are either under- or over-expressed in Alzheimer's patients.
When the researchers compared findings from these 50 genes among Alzheimer's patients, healthy patients, and primates (including chimpanzees and rhesus monkeys), they discovered that, in all but the Alzheimer's group, the number of the specific genes was tightly limited, with little difference in their number between individuals among each of the species. This implies that these genes are important for normal brain functioning, and that their strict regulation in healthy patients is compromised by AD, Stempler explains.
The discovery of this connection is encouraging. "The correlation between metabolic gene expression and cognitive scores in Alzheimer's patients is even higher than the correlation we see in the medical literature between beta amyloid plaques — found in deposits in the brains of Alzheimer's patients — and cognitive scores, pointing to a strong association between cognitive decline and an altered metabolism," Stempler says.
Next the researchers will try to identify biomarkers in the blood that are associated with these metabolic changes. These biomarkers may lead to the detection of AD with a simple and noninvasive blood test.
Source: Tel Aviv University; Nov. 7, 2012.