Odor biomarker may provide early diagnosis of Alzheimer's disease

By John Murphy, MDLinx
Published January 15, 2016

Key Takeaways

Scientists have discovered an odor signature in urine that might be used as a non-invasive biomarker for early diagnosis of Alzheimer’s disease, according a study published online January 14, 2016 in Scientific Reports. Using mouse models of Alzheimer’s, the scientists determined that the odor signature appears before significant Alzheimer-related brain pathology develops.

Previous research on body odor signatures have focused on exogenous sources such as viruses or vaccines. “Now we have evidence that urinary odor signatures can be altered by changes in the brain characteristic of Alzheimer’s disease,” said study author Bruce Kimball, PhD, a chemical ecologist with the USDA National Wildlife Research Center, who is stationed at the Monell Chemical Senses Center, in Philadelphia, PA.

“This finding may also have implications for other neurologic diseases,” he added.

In this study, researchers collected urine samples from three separate lines of APP transgenic mice as well as non-transgenic control mice. They also performed behavioral tests on the mice, which showed that the normal mice could distinguish the difference between urine from other control mice and urine from the APP mice.

When the researchers analyzed the urine samples, they confirmed that all three strains of APP mice produced urinary odor profiles that were distinctively different from those of control mice. Also, the odor differences between APP mice and control mice preceded detectable amounts of amyloid plaque buildup in the brains of the APP mice.

The odor changes didn’t result from new chemical compounds, the researchers noted, but instead reflected a relative shift of the concentrations of existing urinary compounds. Altogether, these findings suggest that the characteristic odor signature is related to the presence of an underlying gene rather than to the actual development of pathological changes in the brain.

“While this research is at the proof-of-concept stage, the identification of distinctive odor signatures may someday point the way to human biomarkers to identify Alzheimer’s at early stages,” said the study’s corresponding author Daniel Wesson, PhD, Assistant Professor in the Department of Neurosciences at the Case Western Reserve University School of Medicine, in Cleveland OH.

But first, extensive studies will be needed to identify and characterize Alzheimer’s-related odor signatures in humans, the researchers cautioned.

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