Interrelationships Between Oxidative Stress, Cytokines, and Psychotic Symptoms and Executive Functions in Patients With Chronic Schizophrenia

Abstract

Objective: Accumulating evidence has demonstrated that the pathophysiology of schizophrenia is involved in various abnormalities in oxidative stress markers and cytokines closely related to synaptic plasticity. However, the interactive effects among key cytokines, oxidative stress, and executive dysfunction and symptoms of schizophrenia have not been investigated yet. Methods: A total of 189 patients with chronic schizophrenia and 60 controls were recruited in the current study. Tumor necrosis factor α (TNF-α), interleukin (IL)-8, IL-6, and IL-2 levels; catalase, glutathione peroxidase, and superoxide dismutase (SOD) activities; and malondialdehyde (MDA) levels were determined in patients and controls. Executive function was evaluated by the Wisconsin card sorting tests, the verbal fluency tests, and the Stroop word-color test. Clinical symptoms were evaluated by the Positive and Negative Syndrome Scale. Results: Relative to the controls, the patients had lower activities of SOD and glutathione peroxidase and levels of TNF-α, but higher levels of MDA, IL-8, IL-6, and IL-2 (all p values < .05). A significant negative relationship between SOD activity and IL-8 levels was found only in patients (β = −0.44, p = .008). Furthermore, we found that an interactive effect of low TNF-α level and high MDA level was associated with negative symptoms (β = −0.02, p = .01). Moreover, the interactive effects of IL-8 and MDA or IL-8 and SOD were correlated with executive function only in patients (β = 0.23, p = .02; β = 0.09, p = .03). Conclusions: Our findings suggest that the interrelationships between oxidative stress markers and cytokines occur in schizophrenia patients, which may be the basis of their pathological mechanisms underlying clinical symptoms and cognitive dysfunction.

Oxidative Stress and Emergence of Psychosis

“…Despite the heterogeneity of the findings presented, it is important to note that lipid peroxidation levels are persistently increased in the blood of chronic SZ patients, and that the TAS and the GSH blood levels are decreased ( Table 3 ). In particular, studies with more than 150 participants recruited, found that the TAS, the GPx and SOD activity were decreased in chronic SZ patients [ 24 , 25 , 26 , 27 ] ( Table 3 , Supplementary Table S1 ).…”

Paeoniflorin Rescued MK-801-Induced Schizophrenia–Like Behaviors in Mice via Oxidative Stress Pathway

“…Data from Wei et al ( 28 ) suggested that oxidative stress mediated particulate matter in the environment was associated with the recurrence of SCZ. On the other hand, several studies reported that natural antioxidant products such as omega-3, vitamin E and vitamin C, intervening and regulating the function of oxidation-system ( 29 , 30 ), which alleviated the symptoms of SCZ.…”

Cognitive Impairment and Psychopathology Are Related to Plasma Oxidative Stress in Long Term Hospitalized Patients With Chronic Schizophrenia

“…Whether the oxidative/anti-oxidative status relates to clinical status of SZ is of particular interest. Numerous studies have explored the relationship between ROS and the severity of different clinical dimensions in schizophrenia (3,15), and found the complex changes of OS have been linked to cognitive impairment and psychiatric symptoms in both preclinical and clinical studies (16)(17)(18). Such as, serum SOD, GSH-Px were shown to correlate with overall severity in acute phase (19).…”