Introduction: Down's syndrome is characterized by an abnormal frequency of coeliac disease and by the frequent occurrence of neurological disorders such as Alzheimer-type dementia of early onset. However, psychosis is rare in Down's syndrome.
Observation: We report the case of a 41-year-old woman, who presented with Down's syndrome. She was living with her parents and had a normal social life. She suddenly experienced some esthesic hallucinations, depression, anorexia, affective flattening and autistic behavior. Biological evaluation revealed macrocytosis, polyclonal IgA and IgG hypergammaglobulinemia and strong positivity for anti-gliadin antibodies of IgG and IgA isotypes. Brain CTscan was normal. Since digestive specimen biopsies did not evidence villous atrophy, we concluded in a silent coeliac disease. After 12 months of gluten-free diet a spectacular and lasting improvement of both psychotic and depressive symptoms was obtained.
Discussion: The effects of abnormal interaction between the immune system and gluten can be expressed not only in the gut (coeliac disease) but also in the brain (psychosis) in genetically predisposed patients, such as those suffering from Down's syndrome. There was evidence for brain disorder related to coeliac disease in our patient.
Conclusion: Our case report shows that, before concluding in Alzheimer-type dementia in Down's syndrome, a biological search for coeliac disease is useful since a gluten-free diet may improve the psychiatric symptoms.