Can a Spinal Tap Help Predict Alzheimer's Disease?

Spinal Tap to Diagnose Alzheimer's?. Hans Neleman Stone/ Getty Images

Scientists who target dementia have a tall order- figure out how to identify, prevent and successfully treat a disease that affects more than 47.5 million people worldwide. One of their many goals is determining how to detect early signs of Alzheimer's and other types of dementia before the symptoms are present.

Think of it like a blood test to check your cholesterol on a proactive basis, rather than waiting for a heart attack to occur and then trying to repair the damage that the heart has sustained.

So how can Alzheimer's (or more accurately, preclinical Alzheimer's) be detected? One method that's being researched is testing cerebrospinal fluid through a lumbar puncture (also called a spinal tap).

In a spinal tap, a needle is inserted into the spinal canal in the lower back (the lumbar section) and fluid is drawn out. That fluid can then be tested for a myriad of medical conditions, including the presence of tau and beta-amyloid protein. Tau and beta-amyloid proteins are prevalent in the brains of people who have Alzheimer's disease, and some research has shown that they also are detectable in cerebrospinal fluid.

Is Testing Cerebrospinal Fluid an Accurate Method to Detect Alzheimer's?

Multiple researchers have conducted studies on cerebrospinal fluid and compared the levels of tau and beta-amyloid proteins to the person's current and future cognitive functioning over the next several years.

Findings have varied, but appear to consistently identify a relationship between cognitive functioning and the amount of these proteins in the fluid.

Some research has suggested that the measure of beta amyloid protein is more strongly correlated with increased risk for cognitive decline than tau. However, other research conducted at Johns Hopkins University found that both tau and beta amyloid levels in cerebrospinal fluid were associated with an increased risk of mild cognitive impairment five years before symptoms were present.

(People with mild cognitive impairment have a high risk of developing Alzheimer's.) Interestingly, higher levels of tau and lower levels of beta amyloid were shown to be the predictors of cognitive impairment. 

Research is not yet to the place where we can definitively diagnose preclinical Alzheimer's disease through cerebrospinal fluid testing alone. However, it does add to the insight we have about the changes in the brain before symptoms are present. This time period where changes in the brain are occurring but the person is asymptomatic appears to be critical as we seek more effective ways to treat and prevent symptoms of dementia.


Alzheimer's Association. Alzheimer’s and Dementia Testing for Earlier Diagnosis. Accessed May 29, 2015.

Archives of Neurology. 2011 Jan;68(1):113-9. Cerebrospinal fluid profiles and prospective course and outcome in patients with amnestic mild cognitive impairment.

Brain. A Journal of Neurology. Volume 138, Issue 3, 772-783. Independent information from cerebrospinal fluid amyloid-β and florbetapir imaging in Alzheimer's disease.

Johns Hopkins Medicine. Finding Alzheimer's Disease Before Symptoms Start. October 16, 2013.

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