Will Pixar's next sequel feature the gut-brain connection?

What if there were more movies about human emotions? ...that dug deeper into the gut-brain connection?

Ooh, the possibilities.

Who would have thought that movies could help with mental-health awareness and education? With scientific research woven into heartwarming stories as seen in the Inside Out movies, writers are certainly pushing the envelope. We secretly wish their recent success leads to MORE content on the science behind how we evolve and adapt, with multiple emotions constantly battling for control of the remote (err...console).

Think messages being delivered by a fast-talking vagus nerve...new adolescence traits and ...an animated army of gut microbes!

It might take us a while to build an award-winning script and send it to the folks at Pixar. Meanwhile, let’s get started with a deeper dive into how human emotions are connected with microbiome health, sprinkled with some basics of human psychology.

It was in the mid-2000s-2010s that scientists started to uncover the gut-brain axis, suggesting a connection between gut microbes and neurological health. Today, we acknowledge that mental health is modulated by the GUT-MICROBIOME-BRAIN AXIS which participates in many important functions - including the production of neurotransmitters and regulating inflammation in the body. The gut is now considered the ‘second brain’ of our body!

Gut microbes exert a huge effect on mental health, via more than one mechanism. The state of our gut microbes can impact the signals being sent to the brain [think ‘Headquarters’ from the movie!] and corresponding behavioral changes.

Here are a few examples.

• Around 95% of serotonin and 50% of dopamine (nicknamed the feel-good, happiness hormones) is produced by gut bacteria. These chemicals regulate feelings of optimism, joy and disgust.
• Gut bacteria also produce acetylcholine, an important neurotransmitter for memory and learning; and GABA (gamma aminobutyric acid) modulates growth, regulates sleep and helps with feelings of calmness, thus preventing anxiety and depression. Multiple studies suggest that modifications in the gut microbiota can contribute to feelings of sadness and thus trigger mental health conditions such as depression.
• Anger modulation is linked with norepinephrine (produced by Bacillus spp), a neurotransmitter that mediates aggressive behavior.
• Social fear and anxiety are regulated by the noradrenergic system and microbial modulation. Reduced activity of serotonin-producing bacteria can also trigger sadness, fear and anxiety.

Microbiome studies continue to establish a strong link between bacterial composition, emotional regulation and subsequent risk for mental-health disorders. The co-existence of mental health imbalances in individuals struggling with digestive issues also validates this connection.

Does that mean gut health programs or probiotics must focus on increasing the count of microbes which produce the ‘good’ or ‘happiness’ hormones? Not really.

Let’s take the first Inside-Out movie as an example. In a poignant scene towards the end, both Joy and Sadness take joint control, which gives the main character some much-needed closure.

This underscores the fact that while certain emotions may be termed ‘negative’, the need for their existence in maintaining optimal emotional health is unquestionable.

The key - is BALANCE.

Mental health starts in the gut. With increasing evidence for its strong influence over mood, behavior and personality, the gut microbiome is slowly and steadily, being prioritized in mental-health intervention programs.

We actively seek more partners for deploying mental-health restoration efforts in schools, hospitals and communities. Tell us if you or someone you know works with individuals suffering from OCD, anxiety-disorders or depression - we’d love to help.

References

1. Barandouzi, Zahra Amirkhanzadeh et al. “Altered Composition of Gut Microbiota in Depression: A Systematic Review.” Frontiers in psychiatry vol. 11 541. 10 Jun. 2020, doi:10.3389/fpsyt.2020.00541
2. Miri, Saba et al. “Neuromicrobiology, an emerging neurometabolic facet of the gut microbiome?.” Frontiers in microbiology vol. 14 1098412. 17 Jan. 2023, doi:10.3389/fmicb.2023.1098412
3. Hoban, A E et al. “The microbiome regulates amygdala-dependent fear recall.” Molecular psychiatry vol. 23,5 (2018): 1134-1144. doi:10.1038/mp.2017.100