Plasma IL-6 levels in unmedicated, comorbidity free obsessive-compulsive disorder

Abstract

Background

Obsessive-compulsive disorder (OCD) is increasingly being evaluated for a neuro-immune basis. Interleukin-6 (IL-6) is the most widely studied cytokine with a potential role in altering neurotransmission. The evidence for plasma IL-6 alterations in OCD has yielded mixed results. Psychotropic medications are known to modulate inflammatory processes and cytokine levels.

Methods

In this study, we recruited unmedicated, co-morbidity-free adult OCD patients (n = 49) and sex-matched healthy controls HC (n = 47) and compared their plasma IL-6 levels and their correlation with age at onset, duration of illness, and severity.

Results

IL-6 plasma level (ng/ml) in unmedicated OCD patients (1.31 ± 0.67) was significantly greater compared to HC (1.03 ± 0.47) [t = 2.33 (p = 0.02)]. The group differences persisted even after controlling for age and sex [F(1, 91) = 4.57, p = 0.035, η² = 0.05]. Plasma IL-6 did not correlate significantly with any clinical variables.

Conclusions

This study adds to the existing literature on immune alterations in OCD. Alterations in plasma IL-6 might have implications in the neurotransmitter alterations and stress-response in OCD. The current study results in unmedicated and comorbidity-free OCD patients give us a better understanding of the immune alterations in OCD. Future studies in such a population will probably help in reducing the heterogeneity of findings.

Keywords:

• Cytokines
• interleukin-6
• obsessive-compulsive disorder
• drug naïve
• immune alterations

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was funded by the INSPIRE faculty award conferred to Dr. Janardhanan C Narayanaswamy by the Department of Science & Technology, Government of India [IFA 12-LSBM 26]. MS is supported by the University Grants Commission, Government of India. VS is supported by Wellcome Trust-DBT India Alliance Early Career Fellowship grant [IA/CPHE/18/1/503956]. GV acknowledges the support of the Swarna Jayanti Fellowship by the Department of Science and Technology, Government of India [DST/SJF/LSA-02/2014–15] as well as Department of Biotechnology, Government of India [BT/HRD-NBA-NWB/38/2019-20(6)].