However, some studies suggested that the partial oxygen pressure (PO 2) in the plasma of brain capillaries may be a physiological parameter that is not necessarily related to the oxygen carrying capacity in the blood (by hemoglobin) 19, 20, 21. These elements of basic physiology have discouraged studies on increasing the fraction of inspired oxygen under normal pressure in depression, as well as other neurological disorders. Therefore, increasing the oxygen content in the air (at normobaric conditions) does not significantly increase the amount of oxygen carried to tissues, except in patients with respiratory disorders. Since almost all oxygen in the blood is bound to the hemoglobin molecule, only a tiny fraction is dissolved in plasma. Transfer of oxygen to the tissues in the human body depends almost entirely on the level and function of hemoglobin in the blood. Particularly, several studies reported mitochondrial function abnormalities in subjects with depression 16, 17, 18. 15 summarized the evidence for the involvement of cellular energy metabolism abnormalities and mitochondrial dysfunction in psychiatric disorders and suggested that new treatment approaches should be directed to this research endeavor. These data reinforce the need for a relentless search for novel efficacious and safe treatment options for depression.Ībnormal cellular energy metabolism due to functional deficiency in oxygen supply and/or mitochondrial dysfunction may lead to alterations in neuronal function, plasticity and brain circuitry. Importantly, few novel therapeutic interventions have been developed and introduced to clinical practice for the treatment of depression in recent years 12, 13, 14.

However, despite the availability of therapeutic approaches, a high percentage of subjects with depression respond poorly, or not at all to administered treatments, with considerable amounts of them suffering unwanted side effects 1, 2, 11. The most widely used treatment strategies for depression are pharmacotherapy, electroconvulsive therapy and cognitive behavioral therapy 1, 2, 7, 8, 9, 10. These estimations may be misleading, the actual numbers presumably even higher, recognizing the cultural-associated differences in inferring and diagnosing mental illness 3, 6.

Depression is a common disorder especially among women 3, 4, with a life-time prevalence ranging between 10 and 20% in the general population 3, 5. This study showed a significant beneficial effect of oxygen treatment on some symptoms of depression.ĭepression is a devastating mental illness causing immense suffering among affected subjects and their families and is associated with severe emotional, functional and financial burden 1, 2. On the other hand, the analysis revealed that there were no significant differences in WHO-5-QOL, SOC-13 or SDS scores between the groups. Similarly, at week four there was a between-group difference of 0.71 points in the CGI score (95% CI − 1.00 to − 0.29 P = 0.001). A multivariate regression analysis showed that the mean ± standard deviation changes in the HRSD scores from baseline to week four were − 4.2 ± 0.3 points in the oxygen-treated group and − 0.7 ± 0.6 in the control group, for a between-group difference of 3.5 points (95% confidence interval − 5.95 to − 1.0 P = 0.007). Evaluations were performed at baseline, 2 and 4 weeks after commencement of study interventions, using the following tools: HRSD Clinical Global Impression (CGI) questionnaire World Health Organization-5 questionnaire for the estimation of Quality of Life (WHO-5-QOL) Sense of Coherence (SOC) 13-item questionnaire and, Sheehan Disability Scale (SDS). Participants underwent a psychiatric inclusion assessment at baseline and then were randomly assigned to either normobaric oxygen treatment of 35% fraction of inspired oxygen or 21% fraction of inspired oxygen (room air) through a nasal tube, for 4 weeks, during the night. In a randomized, double-blind trial, 55 participants aged 18–65 years with mild to moderate depression (had a Hamilton Rating Scale for Depression score of ≥ 8) were recruited to the study from the Southern district in Israel. This study examined the efficacy of normobaric oxygen treatment in subjects with depression. Consistently, several studies demonstrated that normobaric oxygen treatment has clinical benefits in some neurological conditions. Oxygen enriched air may increase oxygen pressure in brain tissue and have biochemical effects even in subjects without lung disease.

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