Science and fashion: inflammation and oxidative stress in psychiatry

Abstract

Science is not immune to fashion, and from time to time, some topics become very trendy in different areas of medicine. The booming interest in inflammation and oxidative stress in medical research in the last decade is a good example. Areas such as oncology and cardiology have taken the lead regarding interest in the role of inflammatory and oxidative stress markers as signs of underlying pathophysiology and their potential therapeutic implications. Psychiatry has followed that lead, and the number of papers addressing immune/inflammatory and oxidative/nitrosative markers has burgeoned in recent years. Many studies show a relationship between these markers, in the form of an imbalance between pro-and anti-inflammatory activity, and almost any psychiatric disorder [1][2][3][4]. Two papers in this issue deal with oxidative disorders in different psychiatric disorders.Bartoli et al.[5] provide a systematic review and metaanalysis of papers assessing uric acid levels in patients with major depressive disorder (MDD). Uric acid is a major antioxidant that accounts for high free radical scavenging activity in humans, including in the central nervous system. In the meta-analysis, MDD patients had significantly lower uric acid levels than healthy controls. Most importantly, the difference with healthy controls was significant only among studies with drug-naïve patients, but not among those involving treated patients. In a limited number of longitudinal studies (n = 4 with 220 patients) assessing uric acid, levels significantly increased after antidepressant treatment. Of course, the results raised a very relevant hypothesis to be tested regarding the effects of drugs used to treat depression on the oxidative and inflammatory systems. However, the present study cannot rule out the possibility that the change in the studies' antioxidants is not related to another epiphenomenon (such as a result of the improvement or stress reduction).Jordan et al.[6] precisely address one of the most fundamental questions on the relationship between oxidative stress and psychiatric disorders (in their study, schizophrenia and depression), that is, whether oxidative stress factors and immune dysregulation are related to the pathophysiology of those disorders or are just a mere epiphenomenon. In a longitudinal study with drug-naïve first-episode patients, they show that most elevated markers in patients were not related to age, sex, disease severity, medication, or adipose tissue mass. However, markers such as 8-iso-PGF2α were associated with smoking or endocrine stress axis activation. The authors highlight the role of lipid peroxidation and the importance of taking into account other confounding factors in biomarker studies of oxidative stress. Despite the fact that, at baseline or after 6 weeks of treatment, oxidative stress measures did not seem to be affected by age, gender, or occasional cannabis use in the whole group of subjects or in each diagnostic group separately, the results should be considered preliminary, given the small sam...

The interplay of psychopharmacology and medical conditions

“…Oxidative stress processes are of high interest in psychiatric disorders (Karanikas, 2023), however, there is much debate as to whether oxidative stress is a possible cause of psychiatric disorders or vice versa (Arango, 2018). Oxidative stress and inflammatory abnormalities were observed in many psychiatric and medical conditions.…”