But why should bacteria in the gut affect the brain? There are several different ways that messages can be sent from one organ to the other. It can be hormones or immune cells via the bloodstream, or by impulses along the vagus nerve, which stretches from the brain to intertwine closely with the gut. Through these pathways, actions in one produce effects in the other.

So how might you go about altering your microbiome to do a spot of brain-hacking? Cryan’s team works on several fronts, investigating the potential to manage stress, pain, obesity and cognition through the gut. “We have unpublished data showing that probiotics can enhance learning in animal models,” he tells me. His team tested the effects of two strains of bacteria, finding that one improved cognition in mice. His team is now embarking on human trials, to see if healthy volunteers can have their cognitive abilities enhanced or modulated by tweaking the gut microbiome.

Another method of adjusting the bacterial profile of your gut is to undergo a transplant that involves taking faecal material from a donor’s intestine – often a close relative – and implanting into a recipient via enema infusion. This unorthodox treatment has been shown to successfully treat infections caused by pathogenic bacteria colonising the gut.

Brain boost

Thankfully, Cryan has a far more appetising method on offer. “Diet is perhaps the biggest factor in shaping the composition of the microbiome,” he says. A study by University College Cork researchers published in Nature in 2012 followed 200 elderly people over the course of two years, as they transitioned into different environments such as nursing homes. The researchers found that their subjects’ health – frailty, cognition, and immune system – all correlated with their microbiome. From bacterial population alone, researchers could tell if a patient was a long-stay patient in a nursing home, or short-stay, or living in the general community. These changes were a direct reflection of their diet in these different environments. “A diverse diet gives you a diverse microbiome that gives you a better health outcome,” says Cryan.

Beyond a healthy and varied diet, though, it still remains to be discovered whether certain food combinations could alter the microbiome to produce a cognitive boost. In fact, Cryan recommends that claims from probiotic supplements of brain-boosting ought to be taken with a pinch of salt for now. “Unless the studies have been done, one can assume they’re not going to have any effect on mental health,” he says. Still, he’s optimistic about the future. “The field right now is evolving very strongly and quickly. There’s a lot of important research to be done. It’s still early days.”

Hacking the brain often conjures up ideas of electrical hardware such as implants and trans-cranial stimulators. But it might be the case that a simple change in diet can shift your brain up a gear. The transhumanists and body hackers who believe that technology is the sole way to improve human ability would do well to pay as much attention to the living augmentation that already resides in their gut.

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