The term NCGS has been defined as one or more of a variety of NON -AUTOIMMUNE morphological or symptomatic manifestations that are precipitated by the ingestion of gluten in people in whom coeliac disease has been excluded
A higher degree of depression and anxiety as been reported in some persons who do not have celiac disease , who are on a regular diet but improved on a gluten free diet and evidence is accumulating that this phenomenon is real
A potential mechanism is via alteration of brain serotonin (5-hydroxy-tryptophan, 5-HT). Decreased brain 5-HT concentration has been long suggested as a cause of depression.[The synthesis of 5-HT in the brain is dependent on the availability of its amino acid precursor, tryptophan. Whether carbohydrate-depleted gluten results in reductions of tryptophan concentration in the human brain requires further exploration. Nonetheless, serotonergic dysfunction due to impaired availability of tryptophan has been shown to play a role in various psychological conditions including depression.
Another explanation involves the so-called gluten ‘exorphins’. These opioid peptides derived from partially digested food proteins including gluten can modulate intestinal function, and can cross the blood–brain barrier and interfere with pain-inhibitory systems, emotionality and memory processes by modulating other hormonal or neurotransmitter systems via the opioid receptors as well as endogenous opioid peptides in the central nervous system.
Most interesting involve gluten-mediated changes in gut microbiota. Several studies have reported intestinal dysbiosis in patients with coeliac disease.[Interestingly, some of the alterations in gut microbiota are restored after adherence to a GFD. This suggests that these changes are secondary consequences of the disease and perhaps directly related to the consumption of gluten. Evidence supporting an important influence of gut microbiota on emotional behaviour and underlying brain mechanisms is well established in adult rodents and is emerging in humans. A recent study has provided first evidence that probiotics can modulate the activity of brain regions involved in processing emotion and sensation in adult women.