In a finding that turns conventional wisdom on its head, scientists suggest that the unpleasant smell associated with flatulence could harbour an unexpected benefit for brain health. Research indicates that hydrogen sulfide, the gas responsible for the notorious rotten-egg odour, might help shield ageing brain cells from Alzheimer's disease.
The Science Behind the Smell: Hydrogen Sulfide and the Brain
A pivotal 2021 study from Johns Hopkins Medicine, published in the Proceedings of the National Academies of Science, investigated the role of this gaseous molecule. While large quantities of hydrogen sulfide are toxic, the body naturally produces it in small amounts to help regulate various functions. The research team, led by Dr. Bindu Paul, discovered that these small doses play a crucial role in cellular messaging within the brain.
The key mechanism is a process called chemical sulfhydration, explained co-author Dr. Solomon Snyder. This process modifies target proteins in the brain. Crucially, the scientists found that sulfhydration levels in the brain decrease with age, a trend markedly more pronounced in individuals with Alzheimer's disease. "Here, using the same method, we now confirm a decrease in sulfhydration in the AD brain," stated collaborator Dr. Milos Filipovic.
Reversing Symptoms in Laboratory Models
To test the therapeutic potential, the team used mice genetically engineered to mimic human Alzheimer's disease. These mice were injected with a compound called NaGYY, designed to slowly release hydrogen sulfide molecules throughout the body. Over a 12-week period, researchers monitored the mice for changes in memory and motor function.
The results were striking. The mice treated with the hydrogen sulfide compound showed a 50% improvement in cognitive and motor function compared to untreated mice with simulated Alzheimer's. The treated mice were better at remembering locations and were more physically active.
"The results showed that the behavioral outcomes of Alzheimer’s disease could be reversed by introducing hydrogen sulfide," Johns Hopkins Medicine noted in a press release. Further experiments revealed the gas's role in regulating an enzyme called GSK3β. In healthy conditions with adequate hydrogen sulfide, GSK3β acts as a signalling molecule. Without it, GSK3β excessively binds to a brain protein called Tau, leading to harmful clumps that block nerve communication and ultimately cause cell death—a hallmark of Alzheimer's progression.
Future Implications for Dementia Therapies
This research provides a novel understanding of the cascade of events leading to neurodegeneration. "Understanding the cascade of events is important to designing therapies that can block this interaction like hydrogen sulfide is able to do," said Daniel Giovinazzo, the study's first author.
Collaborator Dr. Matt Whiteman highlighted the significance of the technological advance, noting that until recently, scientists lacked tools to mimic how the body produces tiny amounts of hydrogen sulfide inside cells. "The compound used in this study does just that and shows by correcting brain levels of hydrogen sulfide, we could successfully reverse some aspects of Alzheimer’s disease," he said.
While the notion of deliberately smelling flatulence is far from a recommended medical intervention, this groundbreaking study firmly links ageing, neurodegeneration, and cell signalling through gaseous molecules like hydrogen sulfide. It opens a new, albeit unconventional, avenue for research into preventing and treating Alzheimer's disease, a condition affecting millions globally.
