Background:
Much is known about the serious neurological effects of gluten ingestion in coeliac disease patients, such as sporadic ataxia, encephalopathy, and peripheral neuropathy, although the causal links to gluten are still under debate. However, such disorders are observed in only a small percentage of coeliac patients. Much less is known about the transient cognitive impairments to memory, attention, executive function and the speed of cognitive processing reported by the majority of patients with coeliac disease. These mild degradations of cognitive functions, referred to as “brain fog”, are yet to be formally recognised as a medical or psychological condition.
Objectives:
This paper will review recent research examining the nature and magnitude of cognitive impairments associated with gluten ingestion in coeliac disease to empirically demonstrate the psychological and neurological reality of the cognitive deficits associated with “brain fog”. Potential mechanisms by which the ingestion of gluten affect neural functions involved in cognitive processing will be examined, focusing on whether the likely mechanism is an extraintestinal manifestation of exposure to gluten per se, a function of the malabsorption of nutrients essential for healthy brain function or the consequence of high levels of circulating cytokines associated with systemic inflammation. The final issues to be discussed will be whether the cognitive impairments in untreated coeliac disease are ameliorated by a gluten-free diet and whether there are any long-term cognitive effects of exposure to gluten.
Conclusion:
The cognitive impairments associated with brain fog are psychologically and neurologically real and improve with adherence to a gluten-free diet. There is not yet sufficient evidence to provide a definitive account of the mechanism by which gluten ingestion causes the impairments to cognitive function associated with brain fog, however current evidence suggests that it is more likely that the causal factor is not directly related to exposure to gluten.