What are Biomarkers?

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Creative Commons Photo Credit: Libertas AcademicaMillions of dollars are being spent on research efforts to find a treatment for Alzheimer’s disease.  These efforts are hampered by the inability to definitively identify who has early stage Alzheimer’s disease, or who might be in the pre-clinical phase of the disease.


As discussed in a previous blog, researchers who develop drugs that show promise must complete a rigorous three-phase clinical trial involving those with the disease to prove efficacy.  Therefore it is crucial that the research community identify indicators of the disease being researched.  These indicators are called biomarkers, and they are used to detect, screen and measure the progression of the disease.


The most effective biomarkers share these characteristics:

  • Safe to use
  • Easy to administer
  • Allowing for objective measurement
  • Cost efficient
  • Providing consistent results across the sexes and ethnic groupings


Examples of effective biomarkers include fasting blood glucose levels to identify diabetes and the presence of certain enzymes in the blood following a heart attack.
At the present time, there are no accepted biomarkers for Alzheimer’s disease, and this lack of knowledge is impeding the ability to conduct definitive clinical testing.   We are not sure what symptoms reliably indicate the presence of the disease. Further, since the disease causes significant damage to the brain itself through the shrinkage of the hippocampus and the destruction of synapses, researchers now believe that any effective treatment must begin during the very early stages of the disease.


As people age, their cognition slows down.  But does an occasional failure to find the right word, or forgetting a date or a name signal the onset of Alzheimer’s?  Often, the answer is no.  Currently, physicians diagnose Alzheimer’s based on measured cognitive decline, at which point clinicians now believe it is too late for effective treatment.  There are a number of other potential biomarkers, but to date, none of them have been sufficiently reliable for the research community to adopt.
Until such time as researchers are able to find a biomarker that accurately identifies those with early stage Alzheimer’s, clinical trials will be stymied.  Positive results may be overstated if people in the trial did not actually have Alzheimer’s.  It is time for the research community to make the identification of a biomarker a top priority.

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