Most treatments for Parkinson’s disease (PD) only slow disease progression. Early intervention for the neurological disease that worsens over time is therefore critical to optimize care, but that requires early diagnosis. Current tests, like clinical rating scales and neural imaging, can be subjective and costly. Now, researchers in ACS’ Analytical Chemistry report the initial development of a system that inexpensively screens for PD from the odors in a person’s earwax.

Previous research has shown that changes in sebum, an oily substance secreted by the skin, could help identify people with PD. Specifically, sebum from people with PD may have a characteristic smell because volatile organic compounds (VOCs) released by sebum are altered by disease progression — including neurodegeneration, systemic inflammation and oxidative stress.

However, when sebum on the skin is exposed to environmental factors like air pollution and humidity, its composition can be altered, making it an unreliable testing medium. But the skin inside the ear canal is kept away from the elements. So, Hao Dong, Danhua Zhu and colleagues wanted to focus their PD screening efforts on earwax, which mostly consists of sebum and is easily sampled.