Does Gluten Cause Neurologic Disease?
The diagnosis of Celiac Disease is made when gluten sensitivity is documented in the context of abdominal symptoms such as diarrhea, abdominal bloating and abdominal pain. The diagnostic term Non Celiac Gluten Sensitivity (NCGS) is used for patients who test negative for Celiac Disease, but have these gastrointestinal symptoms when gluten is ingested.
Beyond the long confirmed association of gluten sensitivity with gastrointestinal disease, there have been many studies performed over the years that have investigated the association of gluten sensitivity with other health disorders, particularly behavioral and neurological disorders. There is accumulating evidence to support a link between dietary gluten intake and a wide variety of neurodegenerative diseases . Observational studies have shown improvements in patients with a variety of disorders when patients were placed on gluten restrictive diets.
Studies have confirmed higher rates of gluten sensitivity in people suffering from bipolar disorder, depression, anxiety, and autism spectrum disorders (ASD).5–8 These observations raise the question as to whether exposure to gluten may actually cause the mechanism by which the body reacts to develop different neurological diseases.
Gluten, contains the primary proteins gliadin and glutenin, which are found in wheat, oats, rye, and barley. These are the prolamin family of proteins and are responsible for gluten’s water insolubility. Gluten proteins are valued for their cohesiveness and their viscus and elastic qualities, which allows for ideal dough and bread consistency.9,10 As a result, gluten content is quite high in a variety of common foods such as bread, pasta, bakery items, and cereals, as well as in sauce thickeners, and fillers.
Gluten seems to cause a pathological immune response in susceptible individuals.10–13 which results in the inflammatory response of the GI tract via which the patient experiences the gastrointestinal distress of bloating , abdominal pain and diarrhea.
These inflammatory effects of gluten resulting in increased intestinal permeability ( leaky gut) leads to the entry of toxic digestive metabolites, and bacterial toxins into the bloodstream which then may reach the central nervous system. 1 Neurological problems such as, cognitive impairment, neuropsychiatric diseases and peripheral neuropathy have all been associated with Celiac Disease. This suggests that the inflammatory response to gluten may be responsible for loss of blood brain barrier integrity with the brains’ exposure to neurotoxic substances. Autism, dementia, Alzheimer’s disease, Parkinson’s disease (PD), depression, anxiety, and schizophrenia.15,17 may all be exacerbated by gluten mediated inflammation.
Although the evidence that exists so far is not sufficient to clearly say that gluten in the diet causes neurological disorders, there have been many observational studies which show that neurological symptoms in many different disorders are improved when gluten intake is reduced or eliminated. 2 Higher than expected rates of chronic diarrhea, constipation, and bloating have been observed in children with Autism 5 and studies have demonstrated improvements in both the prevalence of gastrointestinal symptoms and Autistic behaviors in children placed on gluten free diets Mood disorders (bipolar disorder, depression) are commonly observed in individuals with Celiac Disease and Non Celiac Gluten Sensitivity. Bipolar disorder may be as much as 17 times more likely those with Celiac Disease relative to the general population.6,7 Increased levels of gluten-related antibodies have been documented in individuals with bipolar disorder, depression, anxiety, hyperactivity, and schizophrenia.
It has been observed that patients with schizophrenia have markedly high levels of inflammation, and a gluten-free diet has been shown to improve both psychiatric and gastrointestinal symptoms in these patients.3,18,19
There is a role that one’s genes play in regulating the body’s inflammatory responses to offending substances .Genetic studies are uncovering more about what genetic makeup may cause a person to be more susceptible to nervous system dysfunction occurring as a result of their gluten sensitivity. Studies are ongoing to further elucidate who may have the additional risk attributed to their genetic makeup.Thismaty enhance physician’s awareness and result in better screening of individuals who may benefit by following a gluten restricted diet. In CD and NCGS individuals, it is established that dietary gluten-induced chronic inflammation is linked to dysbiosis and a permeable gut. 16 This in turn affects factors that regulate neuronal inflammation, cognition, and neurodegeneration.
There have been many studies of gluten elimination as a possibly effective treatment strategy for mood disorders.
A review study of existing health databases looked at over 1,100 people’s records to review reports of the effects of gluten on mood disorders. The results of these studies support the association between the worsening of mood disorders with gluten intake in susceptible individuals.
Wheat products are the main source of carbohydrate in the Western diet which therefore results in a high intake of gluten in the general population. In recent years, reports of gastrointestinal and extra-intestinal symptoms, due to gluten-containing foods have been on the increase [4]. In 1956 it was suggested that gluten may be associated with mood and psychiatric symptoms in a case series of subjects without Celiac Disease [16]. More recently, mood symptoms are frequently reported as a result of wheat ingestion [17] with ‘low mood’ being a common motivation for gluten avoidance [18] in the absence of Celiac Disease.
Numerous theories regarding the aetiology of mood symptoms in those with gluten-related disorders exist. The many studies which have been done have not elucidated one clear pathway by which mood disorders occur with gluten ingestion and therefore it appears reasonable to conclude that there is a complex and multifactorial relationship between mood and gluten-related diseases. Regardless, gluten free diets clearly show improvements in some individuals with mental health disorders, and this approach should be tried in patients with these conditions.