BACKGROUND: Compelling evidence links elevated levels of C-reactive protein (CRP) and other inflammatory markers to poor treatment outcome of antidepressant medication. Little is known about the contribution of low-grade inflammation to treatment response to electroconvulsive therapy (ECT) in severely depressed patients.
METHOD: Associations between serum levels of CRP, interleukin-6, interleukin-10, and tumour necrosis factor-α as well as remission of depression, time to remission, and speed of decline of depressive symptoms were examined in 95 older (mean age: 73.1 years) depressed patients treated with ECT.
RESULTS: Moderately elevated levels of CRP at baseline (3 to 10 mg/L), but no other inflammatory markers, were associated with higher remission rates. In patients with moderately elevated CRP levels, the odds ratio for remission was 3.62 (95% confidence interval [CI], 1.09-11.97; p = 0.04). Time to remission was shorter in those with moderately elevated CRP levels (p = 0.05). Speed of decline was higher in patients with moderately elevated CRP levels as compared with those with low CRP levels (decline of 3.2 Montgomery Åsberg Depression Rating Scale points per administration vs. 2.3 points per administration, p = 0.03).
LIMITATIONS: Because of the observational design, residual confounding through other lifestyle or demographic factors cannot be ruled out.
CONCLUSIONS: Although earlier studies showed that low-grade inflammation contributes to poor treatment response in those treated with antidepressants, our study provides clues that low-grade inflammation does not have such a detrimental effect on the treatment response to ECT. This is underscored by our finding that moderately elevated CRP levels were associated with increased remission rates in depressed patients treated with ECT. Replication studies are warranted.