GAD (glutamic acid decarboxylase) antibodies are expressed in type 1 (autoimmune) diabetes, adrenal failure (Addison disease), autoimmune thyroid diseases, premature ovarian failure, myasthenia gravis, pernicious anemia, Stiff-man syndrome and a number of other disorders. An informative study recently published in Acta Neurologica Scandinavica documents the link between these conditions and gluten sensitivity. The authors state:

“The high prevalence of gluten sensitivity in patients with stiff-person syndrome (SPS) lead us to investigate the relationship between gluten sensitivity and GAD-antibody-associated diseases.”

They used ELISA assays for GAD antibodies and serological markers of gluten sensitivity that generated compelling data:

“”Six of seven (86%) patients with SPS were positive for anti-GAD…This compared with 9/90 (11%) patients with idiopathic sporadic ataxia…16/40 (40%) patients with gluten ataxia…and 6/10 patients with type 1 diabetes only…”

Note that the serological tests for gluten sensitivity are a blunt instrument—only 40% of confirmed cases of gluten ataxia were recognized. The abundance of false negatives is why the gluten gene sensitivity test is so valuable.

Additionally, the authors found that…

“The titre of anti-GAD reduced following the introduction of a gluten-free diet in patients with SPS who had serological evidence of gluten sensitivity.”

Their conclusion is simply stated:

“These findings suggest a link between gluten sensitivity and GAD antibody-associated diseases.“

This study is especially interesting in connection with earlier research published in the journal Psychiatry. The authors set out to investigate the role of GAD antibodies in schizophrenia and related disorders:

“We hypothesized that GAD antibodies are increased in patients with chronic psychotic disorders. The aim of this pilot study was to compare the level of GAD antibodies in patients with chronic psychotic disorders with normal controls.”

By way of background they note that:

“The role of GABAergic neurotransmission in epilepsy, anxiety disorders, schizophrenia, and premenstrual dysphoric disorder has been a subject of some recent investigations. Absence of structural abnormalities in the brains of most patients with chronic psychotic disorders has always raised suspicion for an alternative pathogenesis and a possible functional disturbance at the neuronal/cellular level. Glutamic acid decarboxylase (GAD)…is involved in the formation of gamma aminobutyric acid (GABA) a central inhibitory neurotransmitter of the nervous system. Antibodies to GAD may impair GABA formation or inhibitory function.“

What did the data show?

“Serum levels of GAD antibodies in 12 patients with chronic psychotic disorders (schizophrenia and schizoaffective disorders) and 10 age-matched healthy control subjects were evaluated… Antibodies to GAD in patients with chronic psychotic disorders have a higher mean than nonpatient control individuals.”

The authors’ conclusion alerts the practitioner to be on the lookout:

“Antibodies to GAD65 are peripherally present in patients with chronic psychotic disorders (schizophrenia/schizoaffective disorders)... The presence of such antibodies also suggests a possible role for autoimmune mechanism in the pathogenesis of these disorders. In summary, from a practicing psychiatrist’s point of view, measurements of antibodies to GAD65 could potentially be used to screen for chronic psychotic disorders and for diabetes mellitus very early on in the disease process.”

GAD (glutamic acid decarboxylase) produces GABA, the most abundant inhibitory (calming) neurotransmitter in the body. Suboptimal levels can manifest as anxiety, insomnia, hyperarousal, panic, feeling overwhelmed, disorganized attention, restlessness, worry, tension, inner excitability, inability to relax, etc.

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There is a connection between how well you can smell, brain damage from autoimmune inflammation, and psychiatric disease. Consider this fascinating paper published in the journal Clinical Immunology in which the authors discuss the “inter-relationship between olfactory impairment, autoimmunity and neurological/psychiatric symptoms in several diseases affecting the central nervous system (CNS) such as Parkinson, Alzheimer’s disease, autism, schizophrenia, multiple sclerosis and neuropsychiatric lupus erythematosus. We suggest that common manifestations are not mere coincidences. Current data from animal models show that neuropsychiatric manifestations are intimately associated with smell impairment, and autoimmune dysregulation, via autoantibodies…”

In another paper published in the journal Autoimmunity Reviews the authors note that “Research in the field of immunology as well as in various brain illnesses is beginning to indicate the increasing relevance of smell in pathophysiology.” They further state “…evidence exists that there may be something unique about the olfactory system that is inextricably related to immunological function. In addition, accumulating evidence confirms the existence of olfactory dysfunction in brain disease, much of which appears at early stages including multiple sclerosis, Alzheimer’s Disease, Parkinson’s Disease, schizophrenia and depression…under certain circumstances, olfactory abnormalities may be associated with autoimmune conditions. Since the organization of the olfactory system is so sensitive, impairment may be noted at an early stage. This may become important in the prediction of certain brain illnesses.”

This paper recently published in the International Journal of Neuroscience focuses specifically on the link between olfaction, autoimmunity and Parkinson’s Disease. They first describe “the immune alterations observed in PD patients…the increase in the innate immune components including complement and cytokines within their substantia nigra and cerebrospinal fluid (CSF). These alterations extended to the adaptive immune response with the elevation of T cells and autoantibodies…in the peripheral blood and CSF of PD patients.” (Just the kinds of things we test for in the functional medicine approach.) They then describe the link between PD, autoimmunity and olfaction: “Smell deficit is one of the earliest signs of PD and a unique observation suggesting olfactory declines to be a consequence of autoimmune mechanisms.”

And the authors of this study published recently in the journal Autoimmunity observe that “Psychiatric diseases are often associated with mild alterations in immune functions (e.g., schizophrenia) as well as autoimmune features. Recent evidence suggests that autoimmune diseases (AD) demonstrate a higher prevalence of psychiatric disorders, such as depression and psychosis, than in the normal population. Patients with AD often have an olfactory impairment as well, based on smell studies… ” They report that olfactory gene receptors have brain functions in addition to smell, and go on to describe the genetic polymorphisms (variations) that link autoimmunity, psychiatric disorders and smell impairment.

The paper that concludes this post is tantalizingly entitled Olfaction—A Window to the Mind. Published not long ago in The Israel Medical Association Journal, it is available here in its entirety. The authors comment that “The sense of smell can provide a natural window to the brain. This window provides an opportunity to examine neural mechanisms and brain function in a non-invasive way.” They then undertake a fascinating review of the field of olfactory studies encompassing aspects ranging from autoimmunity and neuropsychiatric disease to sexual function, addiction, social behavior and the discrimination of self from non-self. Their conclusion is worth bearing in mind: “…assessment of the sense of smell and olfactory impairments is usually overlooked by patients and their clinicians. Given the clinical data reviewed here, clinicians should be encouraged to screen for olfactory impairments, which can help in the early diagnosis of CNS diseases such as Parkinson, dementia and schizophrenia, as well as CNS-autoimmune diseases such as neuropsychiatric lupus.”

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This paper just published in the Archives of General Psychiatry reports on a randomized, placebo-controlled trial that set out to “determine whether {omega}-3 PUFAs reduce the rate of progression to first-episode psychotic disorder in adolescents and young adults aged 13 to 25 years with subthreshold psychosis.” (PUFAs = polyunsaturated fatty acids) The omega-3s (fish oil) reduced progression to psychosis and improved function. The authors conclude: “Long-chain {omega}-3 PUFAs reduce the risk of progression to psychotic disorder and may offer a safe and efficacious strategy for indicated prevention in young people with subthreshold psychotic states.” I have found that we can predict who will benefit most from fish oil supplementation for psychiatric and neurological conditions with a fatty acid analysis, a blood test that measures the amounts and ratios of fatty acids in cell membranes.

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