Inflammatory Markers May Inform the Effects of Electroconvulsive Therapy on Cognition in Patients with Depression

The neurobiological mechanisms underlying the acute cognitive effects of electroconvulsive therapy (ECT) remain poorly understood. Prior research has shown that proinflammatory cytokines such as IL-6, TNF-α, IL1-β, and IL-10 may interfere with cognitive functioning. Interestingly, immunomodulation is one of the proposed modes of action of ECT. This study investigates whether changes of peripheral levels of IL-6, TNF-α, IL1-β, and IL-10 are related to changes in cognitive functioning following ECT.

In the week before and 1 week after an acute course of ECT, 62 patients suffering from depression underwent a neuropsychological evaluation to assess their processing speed using the Symbol Digit Substitution Test (SDST), verbal episodic memory using the Hopkins Verbal Learning Test-Revised (HVLT-R), and their retrospective autobiographic memory using the Autobiographical Memory Interview (AMI) with the peripheral inflammatory markers being measured at the same 2 time points.

Patients improved drastically following ECT, while their main performance on both the HVLT-R and AMI declined and their SDST scores remained stable. The levels of IL-6 and IL1-β had both decreased, where the decrease in IL-6 was related to the decrease in HVLT-R scores. Higher baseline IL-10 levels were associated with a more limited decrease of the HVLT-R scores.

Our findings tentatively suggest that the effects of ECT on verbal episodic memory may be related to the treatment's immunomodulatory properties, most notably due to decreased IL-6 levels. Moreover, baseline IL-10 appears to be a potential biomarker to predict the effects of ECT on verbal episodic memory. Whilst compelling, the results of this study should be interpreted with caution as, due to its exploratory nature, no correction for multiple comparisons was made. Further, a replication in larger cohorts is warranted.