Bellybutton Smell May Show Parkinson’s Or Cognitive Decline

Parkinson’s currently affects about 153,000 people in the UK. The neurodegenerative condition can lead to both physical symptoms, like tremors, and “non-motor” issues, such as “depression, anxiety, apathy, hallucinations, constipation, orthostatic hypotension, sleep disorders, loss of sense of smell, and a variety of cognitive impairments,” Parkinson’s Foundation writes.

Meanwhile, cognitive decline, which is sometimes seen as a precursor to dementia, is a little harder to measure. But some research suggests it could be on the rise.

Neither condition can currently be conclusively diagnosed with a single test. However, a new study published in the journal Scientific Reports may have found useful clues for both in an unexpected place: our belly buttons.

Apparently, it’s all about the smell.

The paper reads: “The body emits certain odors – from skin sebum or sweat – that serve as early diagnostic warning signs” for conditions like these.

Perhaps surprisingly, this is nothing new. Joy Milne, who learned she could “smell” Parkinson’s, previously led researchers to look into the subject further. After the Milne-inspired study, scientists found 500 smelly chemicals, known as “volatile organic compounds” or VOCs, that are specific to the condition.

As for where these VOCs are most readily available, the research reads: “swabs from the anterior part of the nasal cavity, from the navel, and from the concha part of the ear are less exposed to perfume, soap, and other factors”.

These less exposed body parts aren’t as likely to get covered in things like deodorant, making them a particularly useful source of VOC.

Using new technology called “laser-based photoacoustic spectroscopy”, which analyses the gases on people’s bodies, scientists took samples from these areas.

The 24 participants either had Parkinson’s, mild cognitive decline, Covid-19, or were healthy.

Belly button swabs seemed particularly good at giving distinct smell profiles, from which researchers appeared to be able to identify Parkinson’s, mild cognitive impairment, and Covid-19.

Though the study authors say these results are “promising”, they are only preliminary, and came from a very small sample size (24 people all-in).

And “the study was conducted under controlled laboratory conditions”, whereas in real life, background smell and patient hygiene could provide complicating variables.

Therefore, they ended: “Further validation studies in real-life conditions and on larger, more diverse populations are needed to confirm robustness and generalisability”.