Gluten Sensitivity & Parkinson's Disease

Gluten sensitivity occurs in people with celiac disease (CD). People suffering from CD are unable to eat gluten, the protein found in wheat, barley and rye. People with CD suffer from a wide variety of symptoms, including digestive and neurological symptoms, which has led to conjecture about a possible link with Parkinson's disease.

Considerations

CD is an autoimmune disorder that affects 1 in 133 people worldwide. In these people, gluten attacks the small finger-like projections in the intestines called villi, which leads to malabsorption of nutrients.

Associations

Parkinson's disease is a neurological disorder that affects 1.5 million Americans. It usually affects people over the age of 50 and is characterized by tremors, rigidity, slowness of movement and impaired balance. There has been much conjecture about a possible link between CD and Parkinson's, although there have been no conclusive studies thus far.

Neurological symptoms can occur in CD patients even when they have no digestive problems. This is one of the main reasons why CD is under-diagnosed and is not usually suspected when patients present with neurological problems. In 1966, researchers, Cooke and Smith, first described the neurological manifestations of CD, which included: peripheral neuropathy, myelopathy, optic myopathy, epilepsy and dementia. Prior to that doctors only associated CD with gastrointestinal problems such as: weight fluctuations, diarrhea and/or constipation, anemia and vitamin deficiency.

The fact is that even when CD patients exhibit no digestive symptoms, neurological problems can occur. In 2008, Mayo Clinic researchers uncovered a definitive link between CD and dementia and cognitive decline. According to many medical practitioners, CD should be considered when diagnosing patients with neurological symptoms even when there is no gastrointestinal issue.

Studies

Recent studies have suggested that an even wider spectrum of neurological disorders may be associated with CD and gluten sensitivity: migraine, encephalopathy, chorea, brain stem dysfunction, myelopathy, mono neuritis multiplex and a Guillain-Barre-like syndrome. These associations need to be confirmed by larger epidemiological studies. Other studies have shown a high incidence of gluten sensitivity in genetic neurodegenerative disorders such as hereditary spinocerebellar ataxia and Huntington's disease.

Studies of the gluten-free diet in patients with gluten sensitivity and neurological syndromes have shown mixed results. Diet trials of patients with schizophrenia and autism, two diseases associated with CD, proved inconclusive. Further studies of the effect of a gluten-free diet on the nervous system need to be conducted.

Theories/Speculation

Theories to explain the connection between CD and cognitive decline include the following, according to Dr. Joseph Murray of the Mayo Clinic:

1) Nutritional deficiency
2) Inflammatory cytokines--chemical messengers of inflammation that might cause problems in the brain
3) Immune attacks on the brain that may occur in some patients with CD

Conclusions

For CD patients who have already developed cognitive decline, closely following a gluten-free diet may improve symptoms. Although no correlation between PD and CD has been identified thus far, there is enough research to suggest that patients with CD and neurological symptoms that mimic PD (such as tremors, cognitive decline and neuropathy) may improve on a gluten-free diet.

References

• Cooke, WT and Smith, WT,"Neurological disorders associated with adult coeliac disease." [Brain, December 1966]
• Hadjivassiliou, M et al, "Neuromuscular disorder as a presenting feature of coeliac disease." [J Neurol Neurosurg Psychiatry. December 1997];
• Hadjivassiliou, M et al, "Does cryptic gluten sensitivity play a part in neurological illness?." [Lancet, 347:369-71, February 1996]

Resources

• Mayo Clinic
• National Institute of Health