They believe the digestive tract could help explain the link between spinal injuries and changes in mental health, such as increased anxiety and depression.
University of Alberta researchers found that rats with spinal injuries experienced changes to their gut bacteria and a rise in anxiety-like behaviour.
But when rats with spinal injuries were given faecal transplants from healthy rats, their behaviour, and gut bacteria, remained normal.
The findings suggests that ‘bacteriotherapy’, through some form of “poop pills” could one day be used to improve wellbeing following spinal cord injuries and diseases of the central nervous system.
Physical therapy researcher Karim Fouad, who led the study, said: “I think it has huge potential. The beauty of it is that if this translates to humans, we’d have a simple tool that could potentially improve mental health.”
Researchers have long observed a deterioration of mental health following spinal cord injuries. Patients who experience paralysis are at an increased risk of suicide.
The increased prevalence of depression also means patients often miss their best window for recovery by losing interest in rehab, Fouad said, leading to a worse quality of life.
Connections between poor intestinal health and mental state have also been found outside of spinal cord research.
Research at the University of Alberta has also pointed to how gut health could help explain a disease like multiple sclerosis.
Fouad decided to test for similar connections on spinal cord injuries. When rats received minor spinal cord injuries, he observed a dramatic change in gut flora.
It took up to four weeks for digestive tracts to return to normal.
To test anxiety-like behaviour, Fouad and his team also observed the rats on an elevated plus maze, a widely used test for assessing the anti-anxiety effects of pharmacological agents.
It involves gauging the rodents’ willingness to risk venturing onto an exposed platform.
Three weeks after recovery, injured rats remained far more reluctant to overcome their natural aversion to open spaces than the typical rats.
The next part of the experiment flipped those findings upside down. Some of the
injured rats were given a faecal transplant. They made an astonishing recovery, becoming even more willing to venture out on the exposed platform.
“It’s dramatic,” said Fouad. “Diseases and injuries seem to trigger changes of the microbiome, and this can have much further effects.”
Fouad hopes to test the effectiveness of faecal transplants over time, and to see whether anxiety could be induced simply by adding the wrong gut bacteria to animals raised in sterile environments.
He said there could be wider implications for these findings. Scientists often house animals together in experiments.
But since rats are notorious omnivores – known to eat the faeces of other rats – researchers may have inadvertently skewed thousands of experiments in which gut health was a potential modifying factor.
“How many generations of experiments have been done where microbiome changes were a potential influence and animals were eating the poo and maybe negating the effect?” Fouad said.
“That’s a scary thought.” Faecal transplants might not have the same allure as stem cells for spinal cord patients, Fouad said, but for patients facing a condition in which incremental gains can make a pivotal difference, poop pills could make a big difference.
“Is it going to cure spinal injury? No,” he said.
“But if you’re in a wheelchair and dealing with it in a good mindset, it could make a big difference.”
