Identifying and treating metabolic deficiencies in patients with treatment-resistant depression can improve symptoms and in some cases even lead to remission, a new study has found.
"What's really promising about these new findings is that they indicate that there may be physiological mechanisms underlying depression that we can use to improve the quality of life in patients with this disabling illness," said David Lewis from University of Pittsburgh School of Medicine in the US.
Major depressive disorder, also referred to simply as depression is one of the most common mental disorders.
At least 15 per cent of patients do not find relief from conventional treatments such as antidepressant medications and psychotherapy, said Lisa Pan, professor at Pitt School of Medicine. Depression also is the cause of over two-thirds of suicides that occur annually.
Five years ago, Ms Pan and David Brent, also from University of Pittsburgh, treated a teen with a history of suicide attempts and long-standing depression.
"Over a period of years, we tried every treatment available to help this patient, and yet he still found no relief from his depression symptoms," Ms Pan said. Through a series of biochemical tests, the researchers found that the patient had a cerebrospinal fluid deficiency in biopterin, a protein involved in the synthesis of several brain signalling chemicals called neurotransmitters.
After receiving an analogue of biopterin to correct the deficiency, the patient's depression symptoms largely disappeared and today he is a thriving college student, researchers said.
This prompted them to examine other young adults with depression who were not responding to treatment, said Ms Pan.
In a trial, researchers looked for metabolic abnormalities in 33 adolescents and young adults with treatment-resistant depression and 16 controls.
Although the specific metabolites affected differed among patients, the researchers found that 64 per cent of the patients had a deficiency in neurotransmitter metabolism, compared with none of the controls.
In almost all of these patients, treating the underlying deficiency improved their depression symptoms, and some patients even experienced complete remission. In addition, the further along the patients progress in the treatment, the better they are getting, Ms Pan said. "It's really exciting that we now have another avenue to pursue for patients for whom our currently available treatments have failed," she said. "This is a potentially transformative finding for certain groups of people with depression," she added.
