MAO Enzyme May Become Biomarker of Alzheimer’s Diagnosis and Progression

An enzyme called monoamine oxidase (MAO) may become a biomarker for the diagnosis and progression of Alzheimer’s disease, according to a new study.

The study, “Close Correlation Of Monoamine Oxidase Activity With Progress Of Alzheimer’s Disease In Mice, Observed By In Vivo Two-Photon Imaging,” was published in the journal ACS Central Science.

A hallmark of Alzheimer’s disease is production of beta-amyloid protein plaque, which accumulate in neurons, disrupting their activity and communication. However, the imaging techniques used to check for plaque in the brain are costly, offer limited resolution and require patients to be exposed to damaging radiation.

The field also lacks reliable biomarkers that can help in the diagnosis of the disease and evaluation of its progression.

Previous studies suggested that MAO, an enzyme that has a role in other neurological diseases, such Parkinson’s and Huntington’s diseases and depression, is also associated with Alzheimer’s. But the data came from simple studies, such as examinations of laboratory cell cultures. The scope of the research made it too limited to establish a relationship between MAO activity and Alzheimer’s.

Now, researchers have used mice studies to show that MAO is indeed associated with Alzheimer’s. The team developed a fluorescent imaging tool to monitor, at the same time, the accumulation of beta-amyloid plaque and MAO activity in the brains of mice with Alzheimer’s.

Researchers observed that beta-amyloid accumulation, which indicates disease progression, had a close relationship with MAO activity: The more that neurons accumulated beta-amyloid plaque, the more active MAO would be.

The team identified three stages of MAO activity in the animals: a slow initiation stage from birth to three months, an aggressive stage, and a saturation stage after nine months. Also, MAO activity was found to be higher around deposits of beta-amyloid plaques in older mice.

“The close correlation between the MAO activity and (Alzheimer’s disease) progress observed by in vivo monitoring for the first time prompts us to investigate the enzyme as a potential biomarker of (Alzheimer’s disease),” the authors wrote.