Oxidative Imbalance in Conversion Disorder: Evidence from Thiol-Disulphide Homeostasis Disruption

Conversion Disorder (CD) is a complex neuropsychiatric condition in which stress-related biological changes are thought to play a role. The present study sought to assess oxidative imbalance and inflammation in patients with conversion disorder by examining thiol/disulfide homeostasis and CRP levels as potential biomarkers.

Ninety-six patients diagnosed with Conversion Disorder according to DSM-5 criteria and ninety-six age- and sex-matched healthy controls were included. Psychiatric symptom severity was assessed using the Beck Depression Inventory (BDI) and Beck Anxiety Inventory (BAI). Native thiol (SH), total thiol, disulphide levels, and ratios were measured spectrophotometrically. CRP levels were determined by immunoturbidimetry. Mann-Whitney U-test was applied as appropriate. Effect size calculations were performed and a post-hoc observed power analysis was conducted.

Native thiol and total thiol levels were significantly lower in CD patients compared with controls whereas disulphide levels and disulphide/thiol ratios were significantly higher (all p < 0.001). Effect sizes were large (Native thiol: d = 0.97), and post-hoc power was adequate (>0.95). No differences were observed in demographic parameters between groups. CRP levels were elevated in the CD group (2.61 ± 0.276 vs 1.34 ± 0.227 mg/L, p<0.001).

Our findings indicate that patients with Conversion Disorder may show oxidative imbalance together with elevated CRP levels, supporting the notion that redox and inflammatory pathways could be involved in the disorder's pathophysiology. Thiol/disulfide homeostasis and CRP might therefore represent peripheral biomarkers of interest, although the cross-sectional, single-center design and the restricted set of biomarkers assessed call for cautious interpretation of these results. This is the first study to concurrently evaluate TDH and CRP in CD.