Methionine & Schizophrenia

While a clear cause of schizophrenia has not yet been found, researchers have been busy for decades trying to determine factors that might affect or exacerbate symptoms of this debilitating disease. Some research has shown that a defect in methionine metabolism may influence the course of schizophrenia, while other evidence shows that methionine administration can potentially exacerbate schizophrenic symptoms.

About Methionine

Methionine is classified as an essential amino acid, meaning your body cannot manufacture it from other chemical compounds, but it is required for good health. Your body uses methionine to manufacture creatine -- a substance that plays an important role in energy metabolism -- and uses the sulfur in methionine to regulate normal growth and development. It is naturally in foods including eggs, nuts and seeds, and is also available as a dietary supplement. Methionine has been studied for potential benefits on a number of physical and mental conditions, such as enhancing immune functioning in patients with HIV and improving the outcome of Parkinson's disease. However, these studies are very limited and have had inconclusive results. Some research shows that schizophrenics have elevated levels of methionine and a disturbance in single-carbon metabolism, in which methionine plays a role.

Schizophrenia and Possible Causes

Although exact causes of schizophrenia are unknown, researchers have suggested a number of theories pointing to possible biological influences. One theory is the membrane hypothesis, which states that schizophrenics have a deficiency in nerve cells that causes an overactive transmission of brain chemicals known as neurotransmitters. Another theory suggests a dysfunction in NDMA, or N-methyl-d-aspartate, receptors, can induce schizophrenic symptoms. The single-carbon metabolism theory is based on the function of single-carbon folate, which is responsible for certain metabolic reactions in the brain and also creates methionine. Defects in methionine metabolism are thought to be somehow responsible for the development of schizophrenic symptoms, although the exact role is unclear.

Clinical Evidence

The role of methionine has been studied since the early 20th century for its role in the development of schizophrenic symptoms. A study published in the November 1965 issue of the "American Journal of Psychiatry" found that schizophrenic patients given methionine experienced an exacerbation of their symptoms. Another study published in the September 2005 issue of the journal "Progress in Neuro-psychopharmacology & Biological Psychiatry" showed that methionine levels were elevated in the cerebrospinal fluid of schizophrenic patients, and points to the single-carbon metabolism theory as a possible explanation for schizophrenic symptoms. The main idea posited by the single-carbon metabolism theory is that the deficit in methionine production exacerbates schizophrenic symptoms, although researchers aren't sure exactly why this occurs.

Considerations

If you or someone you know are experiencing symptoms of schizophrenia, you should not attempt to self-diagnose. Consult your doctor or a qualified mental health professional as soon as possible. According to the "PDR for Nutritional Supplements," patients with schizophrenia should avoid methionine supplements.