When a patient seeks help for depression, the first thing the psychiatrist does is encourage the patient to "tell your story." From the symptoms described by the patient and other information gathered in the ensuing conversation, the doctor eventually determines a diagnosis.

Although psychiatrists are trained to diagnose psychiatric disorders, rather than relying on medical or laboratory tests, these physicians must rely on the self-reported experiences expressed by their patients to make diagnoses and provide treatment plans. Because of this, psychiatry is often referred to as a "measureless medicine."

Depression is one of the many psychiatric disorders that lack objective testing for diagnosis and treatment. Homocysteine, however, may be one solution to this lack of objective testing.

Don't be intimidated by the word homocysteine. It might not be a word that is familiar to you, but its function should be, especially if you are someone who struggles with depression!

Homocysteine is a non-protein amino acid that is quickly converted to another amino acid called cysteine. If conversion of homocysteine to cysteine is somehow impaired, homocysteine levels rise and become harmful. Too much homocysteine may increase your risk of stroke, heart disease, free radical activity, and depression.

Several important, mood associated vitamins and minerals (folate, vitamins B12 and B6, and zinc) are responsible for the conversion of homocysteine to the non-harmful cysteine. Therefore, deficiencies in these nutrients can lead to an accumulation of homocysteine. In fact, elevated homocysteine levels can indicate early stage deficiency of folate or vitamins B6 or B12 before blood levels can detect deficiency! This means that homocysteine levels in the body are a strong indicator of health.

Research has shown that an over-accumulation of homocysteine, whether due to a deficiency in folate, B12, B6, or zinc, can lead to depression.

  1. Data from the Health in Men Study, involving 3,752 men aged 73 years or older, found that higher levels of homocysteine increased the risk of depression.  Conversely, lowering homocysteine reduced depression risk by about 20%.
  2. Homocysteine and depression was studied in 44 women with either anorexia nervosa or bulimia nervosa. Self-rated depression scores were significantly correlated with elevated homocysteine levels. Patients suﬀering from severe depressive symptoms tended to have elevated homocysteine levels.
  3. A study in England found that the homocysteine levels of clinically depressed, hospitalized patients were significantly increased when compared to un-depressed control groups. Of the depressed patients who participated in this study, 52% had elevated homocysteine levels.

As you can see, high homocysteine levels are related to depression in men and women alike.

In 2005, a study published in the American Journal of Psychiatry eloquently described the potential relationship between homocysteine and depression. At the time, I was impressed by the strength of their hypothesis and the evidence provided. The study elegantly summarized the link between homocysteine level and depression, vascular disease, and neurotransmitters. The strength of their argument led me to incorporate homocysteine level testing in my own practice. I now routinely test every patient under my care to check their homocysteine levels as well as other vitamins known to be related to depression!

Then, and now, many years later, I continue to feel as though I were the only psychiatrist who read the research, and remain amazed by the lack of notoriety this nutrient receives in the otherwise thoroughly researched and discussed world of depression. 

Yet, the link between homocysteine and depression is not a recent discovery. Reynolds and colleagues first noted the connection in 1970. The fact that we have known about this connection for over FORTY years and that testing for and treating this imbalance remains less than standard practice is absolutely astounding to me. 

[It must be noted, however, that not all depressed people have elevated serum homocysteine, and not all of those with elevated homocysteine are depressed.]

By using a simple laboratory test to reveal a nutritional imbalance which may impact depression, we move from the psychiatric world of trial-and-error to one of scientifically-based individualized treatment. By embracing the concept of biochemical individuality—that every patient is different, that their genetic, biochemical and nutritional status impacts how a person feels, and how, in turn, they are treated-we are able to make well informed decisions about how to help.

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