Cytokines and Cognition in ECT: More Data From Belgium
Out on PubMed, from researchers in Belgium, is this study:
Inflammatory Markers May Inform the Effects of Electroconvulsive Therapy on Cognition in Patients with Depression.
Introduction: 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.
Methods: 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.
Results: 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.
Conclusion: 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.
Keywords: Cognition; Cytokines; Depression; Electroconvulsive therapy; Inflammation.
Discussion
The findings of this exploratory study show that IL-6
and IL1-β are decreased following ECT, suggesting possible
immunomodulatory properties of the treatment.
Moreover, the observed decrease in IL-6 co-occurs with a
decline in verbal episodic memory, as reflected by the decrease
in HVLT-R scores. Finally, this is the first study to
show that higher baseline IL-10 levels predict a more
moderate decrease of verbal episodic memory performance
following ECT.
In conclusion, this report provides preliminary evidence
of a relationship between peripheral IL-6 levels and
cognitive outcomes after ECT, suggesting that there may
be a link between the decrease in verbal episodic memory
seen following the treatment and the concomitant decrease
of peripheral IL-6 concentrations. Further, our
study demonstrates for the first time that higher baseline
levels of IL-10 may be associated with a more limited decrease
of verbal episodic memory performance following
ECT.
Just when you thought the recent burst in data about the immunomodulatory effects of ECT could not continue, here comes more data from our Belgian colleagues. While it may be premature to hang one's hat on these two specific findings, the concept that cytokines might be protective for some complex brain functions (including aspects of cognition) and noxious for others is very interesting. As is quite obvious, this is an evolving story, much replication will be needed, and methodology will continue to be refined. And the ECT research mantra for Denmark applies equally to Belgium: "little country, big data."
This very well written paper is is a must-read for devotees of the inflammation theory of depression, ~20 minutes.
(Please see also blog post of April 26, 2021)
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