The Relationship Between Electric Field Strength Induced by ECT and Cognitive and Antidepressant Outcomes: Data From the Netherlands

 Out on Pubmed, from investigators in the Netherlands, Germany, and the USA, is this study:

The relationship between electric field strength induced by electroconvulsive therapy and cognitive and antidepressant outcomes.

Loef D, Argyelan M, Ruhé HG, Scheepens DS, Schoevers RA, Tendolkar I, van Exel E, van Waarde JA, van Wingen GA, Verdijk JPAJ, Verwijk E, Dols A, van Eijndhoven PFP.Neuropsychopharmacology. 2025 Jan 6. doi: 10.1038/s41386-024-02050-7. Online ahead of print.PMID: 39762574

The abstract is copied below:

Electroconvulsive therapy (ECT) is an effective treatment for depression but is often associated with cognitive side effects. In patients, ECT-induced electric field (E-field) strength across brain regions varies significantly due to anatomical differences, which may explain individual differences in cognitive side effects. We examined the relationship between regional E-field strength and change in verbal fluency score (i.e., category fluency animals score from pre- to 1 week post-ECT; as key proxy of cognitive side effects) across different electrode placements in depressed patients. Secondary, we examined the relationship between regional E-field strength and depression outcome. Using T1 magnetic resonance imaging, we performed E-field modeling in a total of 109 patients. Linear mixed models were executed to analyze the relationship between E-field strength across all 118 brain regions and both cognitive and depression outcomes, while correcting for nuisance variables (e.g., age, total number of ECT sessions, and study cohort). We found that a higher E-field strength was significantly associated with a higher decline in verbal fluency (n = 71, false discovery rate [FDR] corrected p < 0.01) in several brain regions in the left hemisphere (e.g., temporal gyrus and operculum cortex). Moreover, numerous significant associations were found only in the 24 patients treated with right unilateral ECT. No significant relationships were found between regional E-field strength and depression outcome. In conclusion, significant associations between verbal fluency and E-field strength were found in areas crucial for linguistic processing and semantic memory. Our findings underscore the importance of considering individualized dosing strategies to optimize cognitive outcome in ECT, while maintaining its antidepressant efficacy.

The paper is here.

And from the text:

This is a well-presented, sophisticated study with intriguing preliminary findings. One has to believe in the E-field model used, remembering that it is just a model, not an actual measurement in real patients. Replication will be needed. The goal of optimizing ECT efficacy along with cognitive tolerability is a laudable one, if one does not go overboard and sacrifice efficacy, remembering that most cognitive effects are temporary.

These data also ask more questions about electrode placement than they answer. "No differences  were found in category fluency among the electrode placement groups." And the largest cohort of patients was the group that switched from RUL to BL. 

A lot to unpack about the relative efficacy and side effects of the placements. The debate is not yet settled...

Kudos to our Dutch colleagues for this provacative dataset.