This is Spinal Tap: Alzheimer s edition

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Even when elderly individuals begin to show signs of cognitive impairment, it s difficult to know who will go on to develop Alzheimer s disease. A new study suggests that using a spinal tap (lumbar puncture) to measure the levels of certain protein biomarkers may help predict whether a patient with mild cognitive impairment is at risk for the disease.

In a study published in the Archives of General Psychiatry, researchers conducted the longest clinical follow-up to date of patients with symptoms of mild cognitive impairment. After following 137 of these patients for more than nine years on average, the researchers measured two specific biomarkers in cerebrospinal fluid called beta-amyloid and tau. A decrease in the former is associated with the buildup of plaques in the brain in Alzheimer s patients, while an increase in the latter is associated with neurofibrillary tangles.

Using these biomarkers, it was possible to predict, with 90 percent accuracy, who would develop Alzheimer s over the course of the study. Additionally, the researchers found that beta-amyloid was a more reliable early predictor of the disease than tau.

Earlier studies of Alzheimer s predictors have followed patients for a significantly shorter amount of time. However, this study demonstrated that, while some patients with mild cognitive impairment seemed to be stable after a five-year follow-up, some of these patients still ended up developing Alzheimer s later on a finding that suggests even five years is not sufficient for an accurate assessment of Alzheimer s predictors.

It is generally believed that an intervention for Alzheimer s would be more effective if it were initiated early on; thus, predicting Alzheimer s risk as soon as a patient begins showing signs of cognitive impairment could, in theory, be beneficial. More accurate predictions would also help researchers identify the best candidates for clinical tests of potential Alzheimer s treatments. As ACSH s Dr. Ruth Kava notes, This was a preliminary study that won t change practices immediately, but it could be an important avenue for future research.