A new study in the journal Neurology asserts that a spinal tap can accurately detect the development of Alzheimer’s disease before symptoms appear. As quoted in The New Republic, “The unexpected presence of the AD signature in more than one-third of cognitively normal subjects suggests that Alzheimer’s pathology is active and detectable earlier than has heretofore been envisioned.” The “AD signature” is the presence of a protein called beta-amyloid in the spinal fluid. The implication is that people can be accurately diagnosed with Alzheimer’s disease years before they develop symptoms.

This all sounds so neat and clean like genetic testing for neurological diseases such as Huntington’s chorea. As technologies like spinal taps and brain scans become more available outside of research settings, there seems to be increased interest in using them as diagnostic tools. But I feel we are getting ahead of what the data may actually mean. First, a finding of abnormal amyloids does not really mean that one will develop Alzheimer’s disease or become demented. Second, the results of the spinal fluid tests may vary by as much as 30% across different labs indicating a problem with reliability. Third, one often hears that the definitive test for Alzheimer’s disease is autopsy. But this is also not accurate. As many as 25% of elderly people who die and have autopsy studies of their brain have pathological Alzheimer’s disease but do not have memory problems or dementia. Fourth, spinal taps are quite invasive and carry risks that other tests do not. Spinal taps (lumbar puncture) produces headache in about 30% that may start several hours or days after the procedure and last for hours to more than a week. Other risks are for the development of back pain, bleeding, infection, and possible brainstem herniation.

I am all for continued efforts to seek diagnosis and proactive treatments for Alzheimer’s disease. However, spinal taps need to remain in research labs and clinical trials for now. For those who seek my counsel, I would suggest caution. The risks are too great and the useful information provided is too limited and unreliable for clinical purposes. The best clinical plan for diagnosis of memory disorders requires a good medical history (which requires time and informants such as family members who know you well), a work up for treatable causes of memory loss (blood work and imaging study), careful and rigorous memory and cognitive tests rather than screenings, and someone to spend the time to help you and family members understand the results and work out a treatment plan. The bottom line: having amyloid in the brain or being tested positive for Apolipoprotein E4 does not mean you will develop either Alzheimer’s disease or dementia.