S100 and impact of ECT on depression and cognition

Objectives: The main side effects of electroconvulsive therapy (ECT) are in the realm of cognition. The S100-beta is a calcium-binding protein that is expressed by astrocytes in the central nervous system during depression and has been suggested to modulate the impact of ECT on cognition. Methods: Serum samples of S100-beta were taken before and 1 and 3 hours after each ECT session in 12 depressed patients (mean age, 54 years), treated with bilateral ECT twice weekly (mean, 6 sessions). Measures of depression (Symptom Checklist-90 depression dimension) and a neurocognitive test battery yielding 3 domains of general cognition, memory, and subjective cognitive impairment were administered 1 day before and 5 and 30 days post-ECT. Results: Electroconvulsive therapy was associated with a reduction in depression and subjective cognitive impairment at 5 and 30 days post-ECT. Electroconvulsive therapy was associated with a small but significant rise in S100-beta 1 hour post-ECT (adjusted B = 0.013, P = 0.035), with a directionally similar but reduced effect size at 3 hours post-ECT (adjusted B = 0.010, P = 0.10). Higher level of S100-beta at baseline was associated with poorer memory function at 5 and 30 days of follow-up (adjusted B per tertile group increase, 0.38, P = 0.013) but also with less subjective cognitive impairment (B = -28.2, P < 0.001) and less depression at follow-up (B = -15, P = 0.009). Conclusion: The S100-beta at baseline may be a marker predicting and possibly mediating the differential impact of ECT on cognition and depression.