Oxygen Therapy for Moderate Depression

In a pilot trial, researchers have reported that treating mild to moderately depressed individuals with oxygen-enriched air had "a significant beneficial effect" on some depression symptoms.

Fifty-one participants completed four weeks of the oxygen vs. placebo treatment. The trial was designed to test the idea that delivering oxygen at normal atmospheric pressure ("normobaric") in moderately higher concentration than ambient air might improve certain aspects of brain function and provide some measure of relief from depression symptoms.

The concept is not to be confused with "hyperbaric" oxygen therapy, or HBOT, which is used in medical facilities around the world to speed healing of carbon monoxide poisoning, gangrene, stubborn wounds, and infections in which tissues are starved for oxygen. Those who receive hyperbaric oxygen must enter a special chamber to breathe pure oxygen at air pressure levels 1.5 to three times higher than normal.

A team at Ben-Gurion University of the Negev in Israel co-led by 2007 BBRF Independent Investigator and 1996 Young Investigator Yuly Bersudsky, M.D., Ph.D., and Abed N. Azab, Ph.D., had the idea of testing normobaric oxygen treatment in depression, after previously trying it in a pilot trial involving individuals with schizophrenia.

In their paper appearing in Scientific Reports, the team noted prior studies in which highly enriched or pure oxygen delivered at normal atmospheric pressure impacted a measure called oxygen partial pressure in brain tissue, leading to improved function of mitochondria, the ubiquitous energy factories that power our cells.

The researchers sought to determine whether treating depressed individuals with oxygen that is only moderately enriched, at standard atmospheric pressure, might similarly improve mitochondrial function or affect brain biology in other ways that might be therapeutic.

The 51 participants who completed the trial were randomized to receive either oxygen-enriched air (35 percent oxygen) or ambient air (21 percent oxygen), delivered through a nasal tube during the night, for seven to eight hours per night, over a four-week period. Any medications the participants were already taking continued to be administered during the trial. Twenty-nine of the 51 received oxygen-enriched air treatment, while 22 received ambient air, which served as a placebo. The air was delivered via the same equipment so that neither group knew whether they were in the treatment or control group. The study was double-blinded, meaning those administering the treatments also did not know the identity of participants receiving enriched oxygen therapy.

Sixty-nine percent of those in the enriched oxygen treatment group improved over the 4 weeks, compared with 23 percent in the control group. The severity of symptoms was measured in all participants using a number of different scales, two of which showed significant improvement while the others showed no improvement.

Benefits were experienced in depressive and anxiety symptoms and in "cognitive disturbance," including a decrease in suicidal thoughts, feelings of guilt, and insomnia, among other positive therapeutic effects. There was some suggestion that the therapy also improved coping ability. No significant side effects were seen in any of the study participants.

The team said that the notable differences between the treated and control groups were evident only after four continuous weeks of oxygen therapy. While their study was not designed to determine how or why oxygen therapy may have beneficially impacted brain function, they hypothesize that raising the pressure of the dissolved oxygen portion of blood plasma affects oxygen pressure at key enzymes, and perhaps in mitochondria, possibly causing beneficial effects.

The results were encouraging to the team, which said the concept, being "simple, non-invasive, and safe," merits further exploration in larger replication studies. These would ideally include more patients including some with severe depression symptoms and might test enhanced oxygen over longer periods and with follow-ups to measure the efficacy and durability of the pilot study's results.