The neurological and psychiatric implications of coeliac disease
The Nutrition Society Paper of the Month for May is from Nutrition Research Reviews and is entitled ‘The progression of coeliac disease: its neurological and psychiatric implications‘, by Giovanna Campagna, Mirko Pesce, Raffaella Tatangelo, Alessia Rizzuto, Irene La Fratta, Alfredo Grilli.
Coeliac Disease (CD) was recently presented by The European Society for Pediatric Gastroenterology, Hepatology and Nutrition, describing it as “… an immune-mediated systemic disorder elicited by gluten and related prolamines in genetically susceptible individuals and characterized by a variable of gluten-dependent manifestations, CD-specific antibodies, HLA-DQ2 or HLA-DQ8 haplotypes, and enteropathy” . This broader view of the disease seen as an inflammatory disease is supported by clinical observations of extra-intestinal manifestations such as dermatologic, hepatic, osteologic, endocrine and neurological signs .
Untreated CD patients are characterized by more neurological symptoms. Cerebellar ataxia is one of the first symptoms, and one of the most frequently recognized neurological disturbances in CD . It could be followed by other neurological complications, such as epilepsy , and peripheral neuropathy that has been evidenced in up to 50% of cases . Nevertheless, adult patients suffering from CD, reported milder to severe forms of cognitive impairment . The milder form is known as ‘brain fog’ which is characterized by the difficulty in concentrating, problems with attentiveness, short-term memory lapses, difficulties in word-finding, temporary loss in mental acuity as well as confusion and/or disorientation .
The association of CD with psychiatric disorders has also been identified for a long time. Psychiatric symptoms have been reported as common complications in many patients suffering from CD, though the effects of a diet on one’s mood and psychiatric symptoms remain largely unknown . Psychiatric symptoms usually presented include depressive symptoms, apathy, excessive anxiety, irritability , eating disorders , attention deficit/hyperactivity disorder  and autism  as well as sleep disorders that are inversely related to the Quality Of Life .
It is still not fully explained how the pathogenic mechanism of CD affects the patient’s mental health, but one hypothesis suggests that it is due to the serotonin imbalance or due to the opioid neuro-transmission caused by gluten and gluten metabolites which effect the Central Nervous System (CNS) . Given that the gastrointestinal tract is connected to the CNS, this means that the communication involves neural pathways as well as immune and endocrine mechanisms. The intestinal barrier prevents toxins, pathogens and antigens in altering the various neuro-active compounds .
The existence of a rich gut-to-brain communication increases the possibility that intestinal barrier alterations could take part in the pathophysiology of CNS disorders and therefore determine the neuropsychiatric symptoms .
To date, the only treatment for CD with complete remission of the symptoms is a lifetime diet with the total elimination of gluten. Even the ingestion of small amounts of gluten could cause major disruptions, therefore adherence to a gluten-free regimen is effective in the treatment of depression, anxiety and neurological complications associated with CD. While some of these symptoms could improve with a GFD, our advice is to diagnose CD as early as possible, given that delays in the diagnosis could cause severe implications in the nervous system. The importance of an early diagnosis is fundamental and the only treatment available is a GFD to be followed for a lifetime.