The first of its kind study, published in Nature’s Molecular Psychiatry, notes that there is growing evidence that microbes in the gut can play an important role in regulating brain functions –particularly emotional processing and behaviour.
Led by scientists at the APC Microbiome Ireland SFI Research Centre at University College Cork, the research used a mouse model to focus on cognitive declines in middle age – noting that middle age is a time of life where various physiological changes occur and can lead to alterations of brain function, including cognitive impairments, but that the mechanisms underpinning such changes are unclear.
“We wanted to see whether an inulin enriched diet that can modulate the composition of the microbes in the gut could also improve brain health and wellbeing” said Professor John Cryan, who led the study.
“The community of microbes in the gut changes with ageing. Many studies in ageing focus on very old animals and this may be too late to reverse the age-associated changes. We chose middle age in the hope that we could promote healthy ageing”
Findings from the new research suggest that prebiotic dietary fibres could be developed as a new strategy to promote healthy ageing, by protecting brain functions and preventing the adverse effects of age-related neuroinflammation.
Fibre: The Ferrari for your brain?
Prebiotics are non-digestible fibres that promote the growth of beneficial bacteria in the intestines.
Inulin is one such prebiotic found in a wide variety of fruits, vegetables, and herbs, including wheat, onions, bananas, leeks, artichokes, asparagus and chicory.
The team suggested that their findings may mean that prebiotic fibres – rather than fancy cars or motorbikes – is what is needed for that midlife crisis.
“Microglia are the major immune cells in the brain and have shown to be a key player in neuropsychological and neurodegenerative conditions. Moreover, microglia play a crucial role in brain plasticity and cognition,” explained Dr Marcus Boehme – first author of the study.
“Our research shows that a diet supplemented with prebiotics reversed microglia activation in the middle- aged mouse brain towards young adult levels,” he commented. “Moreover, this reversing effect was observed in a key region of the brain which regulates learning and memory, the hippocampus.”
The team tested whether targeting the gut microbiome by prebiotic supplementation could alter microglia activation and brain function in ageing.
Using male young adult (8 weeks) and middle-aged (10 months) C57BL/6 mice, the team examined the impact of a diet enriched with a prebiotic (10% oligofructose-enriched inulin) or control chow for 14 weeks.
“Prebiotic supplementation differentially altered the gut microbiota profile in young and middle-aged mice with changes correlating with faecal metabolites,” reported the team. “Functionally, this translated into a reversal of stress-induced immune priming in middle-aged mice.”
In addition, they reported a reduction in ageing-induced infiltration of Ly-6Chi monocytes into the brain coupled with a reversal in ageing-related increases in a subset of activated microglia (Ly-6C+).
“Taken together, these data highlight a potential pathway by which targeting the gut microbiome with prebiotics can modulate the peripheral immune response and alter neuroinflammation in middle age,”
The APC team concluded that the new data in mice highlights a novel strategy for potentially fighting age-related neuroinflammatory conditions and cognitive decline.
Source: Molecular Psychiatry
Published online ahead of print, doi: 10.1038/s41380-019-0425-1
“Mid-Life Microbiota Crises: Middle Age is Associated with Pervasive Neuroimmune Alterations that are Reversed by Targeting the Gut Microbiome”
Authors: Marcus Boehme, Marcel van de Wouw, et al