"A test won't be beneficial for screening in a population if there are no current effective interventions (treatments) that can significantly affect the natural history of the condition for which one is screening, which is currently the case for Alzheimer's disease," said Dr. Ken Langa, co-director for the Center for Research and Education at the University of Michigan Health System, in an e-mail.
Dr. Clifford Saper, chairman of the department of neurology at Beth Israel Deaconess Medical Center, said until experts are able to successfully treat Alzheimer's disease, there is no reason to perform this test on patients with MCI or Alzheimer's disease.
"This test shows up positive in presymptomatic individuals, and Alzheimer's disease is a common disorder," said Saper. "The main value would be to detect [Alzheimer's disease] in atypical cases."
There are more steps to take to besides researching whether the test works, according to the coinciding editorial published in Archive of Neurology. Less experienced physicians would need to get comfortable with the idea of taking the time to prepare and perform a spinal tap. Patients and physicians would need to understand the risk involved in taking the test, and understand what the results mean.
And, according to Dr. William Hu, assistant professor of neurology at Emory University School of Medicine, the question is not whether the test works to identify potential markers for the disease, but whether those who have these markers actually develop the disease in the long run.
"The key question remains whether some the cognitively normal subjects with the [Alzheimer's disease] signature will go on to develop clinical disease, have the signature because of shared risks for [Alzheimer's disease] as those who do have the disease, or are resistant to disease despite similar changes in the brain," said Hu.
Dr. Gary Kennedy, director of the division of geriatric psychiatry at Montefiore Medical Center, said even if the test found that a higher amyloid protein may be a marker for Alzheimer's disease, there are still no successful anti-amyloid treatments available. The relevance of this marker so far is limited to confirming the diagnosis, said Kennedy.
"The real impact of these findings will be in subsequent studies of anti-amyloid drugs where spinal fluid can be used to test their immediate effects," said Kennedy. "Even so we still need to determine if lowering amyloid levels is associated with improved memory."
"We have a long way to go," he said.