February 2017

Derek K. Tracy, Dan W. Joyce, Sukhwinder S. Shergill

Full text: The British Journal of Psychiatry Feb 2017, 210 (2) 174-175; DOI: 10.1192/bjp.210.2.174

‘Psychobiotics’ may sound like a particularly vicious dietary programme, but it’s actually a proposed novel form of psychiatric medication.
We’ve endured several years of advertising guff about yogurts with various purported health benefits, but actually the data on a two-way link between your stomach and the brain have been growing. In particular, your gut biome (“good” and “bad” bacteria, if you’re a Yakult drinker) and immune status appear able to modulate cognitive and psychological functioning, so it seems an obvious next-step to ask if this might prove a therapeutic target. One problem has been that the typical ‘probiotic cocktail’ involves numerous bacterial strains, so it is difficult to disentangle any effective element that might be contained within. A new study has explored administering just one – the snappily named Bifidobacterium longum 1714 - to healthy volunteers, and measured how it impacted their response to a social stress test. The bacterium reduced subjectively reported anxiety levels and, fascinatingly, produced relevant biological changes: decreasing cortisol levels and producing EEG changes consistent with enhanced prefrontal cortical activity. Early days in this field, so not yet time to amend the platitude to state that the way to a man’s brain is through his stomach. However we offer up to yogurt manufacturers the catchy “As seen in Kaleidoscope!” jingle…

The burdens of mental illnesses are clearly enormous, so, to phrase it rather crudely, one might expect evolutionary pressures to ‘breed them out’.
To reverse this, are there evolutionary gains, at least at a population level, that help maintain them in our gene pool? With psychoses, there are growing data linking them with creativity and language expression, alluding to associations with core aspects of being human. For depression, there is a social evolutionary theory that it is a mechanism for avoiding conflict with powerful and dominating individuals, though this remains less convincing and satisfying as a hypothesis. Fitting with the previous article on psychobiotics, new work proposes that depression is a result of an evolutionary co-existence with microbes over the millennia. The idea goes that depression produces a ‘sickness behaviour’ leading a responding immune system to energy conserve and avoid social contact; the ‘illness’ is thus an adaptive response that helps ensure survival. It also explains, the authors argue, known environmental and genetic risk factors, the acute phase inflammatory response, and the greater female preponderance of illness.

We certainly know stress is linked with mental ill-health, and there has been a considerable amount of work looking at rates in healthcare professionals, but what about students?
Although temporarily sheltered from most of the vagaries and pressures of everyday life in the NHS, they face – as we all recall only too vividly – multiple stressors, from exams to irate and irrational Consultants (only very rarely for the latter factor, I hasten to add). A meta-analysis has evaluated work on medical students across the globe, and found a prevalence of depressive symptoms of 27%. To put that in context, the figure is about 9% for an aged-matched group outside of medicine. Worryingly, 11% had suffered suicidal thoughts, and only one in six of those with depressive symptomatology had sought any help. A linked article in Kaleidoscope asks what can be done, exploring interventions to reduce burnout. The finding that stood out the most was how little benefit was typically gained from individual interventions, and that for change to occur, it needed to be at a systems-level in the organisation: work-based stress is not a problem ‘in’ a person, it’s a problem ‘in’ a team or service.