Biomarkers and Biopsies: The New Neurology Toolkit?

Bret Stetka, MD; José G. Merino, MD, MPhil

Disclosures

May 29, 2012

Editor's Note:

At the 2012 Annual Meeting of the American Academy of Neurology (AAN) in New Orleans, Louisiana, Medscape sat down with José G. Merino, MD, MPhil, to discuss promising advances in dementia, Parkinson disease, and stroke, which were presented at the meeting. Dr. Merino is a neurologist at Johns Hopkins Community Physicians in Bethesda, Maryland; a member of the AAN Science Committee; and moderator of this year's AAN Hot Topics session.

Biomarkers and Biopsies

Medscape: There were some interesting presentations on the role of biomarkers in neurology at this year's meeting. What struck you as most interesting, and how might biomarkers one day affect practice?

Dr. Merino: This year there was an interesting Integrated Neuroscience Session (INS) looking at how the field of biomarkers is going to change how we practice medicine. There are several ongoing initiatives looking at biomarkers in Alzheimer disease, Parkinson disease, traumatic brain injury, multiple sclerosis, and even in multiple system atrophy.

Biomarkers will hopefully help us accurately diagnose these conditions, even in their early stages; identify who will respond to treatment; and optimize clinical trials. There are several ongoing National Institutes of Health (NIH)-funded initiatives to identify and validate biomarkers that may be of clinical use in a variety of conditions, like Alzheimer and Parkinson disease, multiple sclerosis, traumatic brain injury, and spinal muscular atrophy.

Biomarkers, when combined with a detailed clinical history and examination, allow us to see who has latent disease and may help us understand the pathophysiologic processes in the brain that lead to disease. In a very interesting talk, Dr. Thomas Montine[1] from the University of Washington explained how the levels of CSF-tau fall as patients develop clinically evident cognitive impairment at the same time that amyloid-beta accumulates in the brain. These imaging and fluid biomarkers can help identify patients who are cognitively normal but have significant neurodegenerative brain pathology, like plaques and tangles, Lewy bodies, and microvascular disease, and thus are candidates for enrollment in trials of agents to slow the progression of the disease. At the same time, these biomarkers increase our understanding of the pathophysiologic processes in the brain that lead to symptoms.

A Skin Biopsy for Parkinson Disease?

Dr. Merino: Dr. Rodriguez-Leyva[2] from the University of San Luis Potosí in Mexico presented another very nice example of the potential use of biomarkers. He found that detecting alpha-synuclein in a skin biopsy could help differentiate patients with Parkinson disease from patients with an atypical type of parkinsonism. Patients with Parkinson disease have a very high concentration of alpha-synuclein in the epidermis, whereas those with atypical parkinsonism don't. Thus, a relatively simple diagnostic test could help identify patients early who may benefit from specific treatments. This is an example of a biomarker that could eventually be used to select patients for clinical trials. And clinically, an inexpensive, simple punch biopsy of the skin could obviate the need for a treatment trial to determine whether someone has an atypical form of parkinsonism that does not respond well to the drugs used to treat Parkinson disease.

Medscape: So, this could be used as a preclinical screening method?

Dr. Merino: Yes, or in patients who have symptoms but who you're not sure have Parkinson disease vs another cause of parkinsonism.

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