Researchers into multiple sclerosis at Mount Sinai Hospital in New York City were looking at how antibiotics affect the myelin sheath and neuron damage when they noticed that the mice they were using were exhibiting behavioral changes, in terms of depressive symptoms. Upon further examination, they realized that a specific mix of antibiotics reversed these symptoms of depression. More specifically, they were able to determine that bacteria in the family of Lachnospiraceae and Ruminococcaceae caused depression by generating metabolites (mainly one called cresol) which caused depression.[i]
As I’ve mentioned many times before, this brain/gut axis is, of course, bi-directional. For example, 2015 research showed that separating newborn mice pups from their mothers for 3 hours per day led to statistically significant changes in the gut bacteria. And research out of Duke last year showed that socialization is necessary not only for chimps’ mental health, but also for their gut microbiome.[ii]
An article in Psychology Today states that, according to the National Institute of Health, this time of year has a particularly high rate of depression, and hospitals and police forces report increased incidences of suicide and attempted suicide.[iii] A recent article in the Huffington Post examined the question of why: “Between stressful end-of-year deadlines, family dysfunction and loss, poor eating and drinking habits, and increasingly cold and dark winter days, it’s easy for the holiday season to feel not-so-merry and bright.”[iv]
Stress, poor eating, and drinking undoubtedly affect our microbiota. It also occurs to me that since some of our gut bacteria are circadian[v], you do have to wonder if depression at this time of year (including seasonal affective disorder) is not, in part at least, caused by changes in the biome.
Time will tell, I imagine, since research into the gut/brain axis has exploded worldwide. In the meantime, though, caring for your biome maybe the best present you can give yourself.
[i] Gracias, M, et. al. Microbiota-driven transcriptional changes in prefrontal cortex override genetic differences in social behavior. Elife. 2016 Apr 20;5.