Gut microbiota disturbance during helminth infection: can it affect cognition and behaviour of children?

Abstract

Background: Bidirectional signalling between the brain and the gastrointestinal tract is regulated at neural, hormonal, and immunological levels. Recent studies have shown that helminth infections can alter the normal gut microbiota. Studies have also shown that the gut microbiota is instrumental in the normal development, maturation and function of the brain. The pathophysiological pathways by which helminth infections contribute to altered cognitive function remain poorly understood.

Discussion: We put forward the hypothesis that gastrointestinal infections with parasitic worms, such as helminths, induce an imbalance of the gut-brain axis, which, in turn, can detrimentally manifest in brain development. Factors supporting this hypothesis are: 1) research focusing on intelligence and school performance in school-aged children has shown helminth infections to be associated with cognitive impairment, 2) disturbances in gut microbiota have been shown to be associated with important cognitive developmental effects, and 3) helminth infections have been shown to alter the gut microbiota structure. Evidence on the complex interactions between extrinsic (parasite) and intrinsic (host-derived) factors has been synthesised and discussed. While evidence in favour of the helminth-gut microbiota-central nervous system hypothesis is circumstantial, it would be unwise to rule it out as a possible mechanism by which gastrointestinal helminth infections induce childhood cognitive morbidity. Further empirical studies are necessary to test an indirect effect of helminth infections on the modulation of mood and behaviour through its effects on the gut microbiota.

Keywords: Central nervous system; Development; Gut microbiota; Helminths; Mental health; Microbiota-gut-brain axis.

Fig. 1

The microbiota-gut-brain axis and its interactions with soil-transmitted helminths (STH): (1) shows the bidirectional communication between the gut and the brain, which occurs through multiple pathways that include hormonal, neural and immune mediators; (2) shows the impact of gut microbiota dysbiosis on cognition; (3) shows the impact of helminth infection on the gut microbiota. The dotted arrow shows the hypothesized pathway leading from STH infection to cognitive impairments, potentially through its impact on the gut microbiota (i.e. dysbiosis). Adapted from De Palma et al. 2014 [65]