This computational modeling study quantified how race- and sex-related cranial anatomy affect predicted brain-wide electric-field (E-field) distributions during electroconvulsive therapy (ECT) across conventional and experimental electrode montages. The authors aimed to determine whether race-associated anatomical variability meaningfully contributes to differences in ECT stimulation metrics across montages and to compare the relative effects of montage, race, and sex on stimulation strength, focality, and hemispheric laterality.
Finite element head models were constructed from high-resolution magnetic resonance imaging for three demographic cohorts: Chinese, Black, and Caucasian. The total sample comprised N = 150 head models, with n = 50 per cohort. Each cohort included 25 males and 25 females aged 20–30 years. Simulations were performed using the Realistic vOlumetric-Approach-based Stimulator for Transcranial electric stimulation (ROAST) pipeline.
Five ECT electrode montages were simulated under a constant-current condition of 900 mA: bifrontal (BF), bilateral/bitemporal (BL), right unilateral (RUL), focal electrically administered seizure therapy (FEAST), and frontomedial (FM). The same current amplitude (900 mA) was applied across montages to permit direct comparisons of resulting E-field distributions.
Stimulation strength was quantified as the ratio Ebrain/Eth where Ebrain is the 90th percentile of brain-wide E-field magnitude and Eth is the neuronal activation threshold set to 0.25 V/cm. Overall focality was evaluated as the percentage of brain volume with E-field magnitude at or above the activation threshold (Ebrain ≥ Eth). Hemispheric laterality was quantified as the median right-to-left hemispheric E-field magnitude ratio.
These predefined metrics allowed comparative assessment of how montage, race, and sex influenced the intensity, spatial extent, and lateralization of predicted ECT-induced E-fields across the modeled cohort.
Across the simulations, electrode montage exerted the strongest effect on all three primary metrics. The study reported the following montage effects on stimulation strength and distribution:
BL and FEAST produced the highest predicted stimulation strengths (largest Ebrain/Eth values).
RUL and FM produced intermediate stimulation strengths.
BF produced the lowest predicted stimulation strength and was associated with the most focal stimulation among montages tested.
In terms of laterality, montage again dominated: FEAST produced the greatest hemispheric asymmetry, followed by RUL. Montage also influenced focality: BL, RUL, and FEAST stimulated substantially larger brain volumes above the activation threshold (indicating less focal stimulation) compared with BF.
Systematic differences in cranial anatomy across racial cohorts produced measurable differences in predicted E-field intensity and distribution. Key race-related findings included:
Caucasian head models generally predicted higher stimulation strengths (higher Ebrain/Eth) than Black and Chinese head models under the same montage and current conditions.
Lower focality (i.e., a larger percentage of brain volume exceeding the activation threshold) was observed in Caucasian models relative to Black and Chinese models.
For laterality, Chinese head models demonstrated higher right-to-left hemispheric E-field ratios than both Black and Caucasian models, indicating greater predicted asymmetry under the same montage conditions.
These race-associated differences are reported as systematic and attributable to anatomical variability represented in the MRI-derived head models.
Sex-related differences were reported but were smaller in magnitude than montage- or race-related effects. The study observed that:
Females predicted modestly higher stimulation strengths (Ebrain/Eth) than males across the modeled cohort.
Females also showed lower focality (larger stimulated brain volume above Eth) than males.
These sex-related patterns were consistent across cohorts but described as less influential than montage and as secondary to race-related effects.
The authors statistically analyzed the effects of race, sex, and montage on stimulation strength, focality, and laterality. Montage emerged as the primary determinant of predicted ECT-induced E-field intensity, spatial extent, and hemispheric asymmetry. Race-related anatomical differences produced systematic modulations of these metrics, and sex-related differences produced smaller systematic shifts. Specific p values or detailed statistical tables were not reproduced here; the source reports that these effects were statistically analyzed but does not present them in this summary text.
The study concludes that electrode montage is the dominant factor determining predicted ECT stimulation strength, focality, and laterality. However, race-related cranial anatomy and, to a lesser degree, sex-related anatomy systematically alter predicted stimulation patterns under identical current and montage conditions. The authors suggest these findings support consideration of individualized anatomy when planning ECT dosing and treatment optimization.
The study was partially funded by NIH grants listed in the source. Several authors (NK, YH, DT, AD) were employed by Soterix Medical, Inc.; these affiliations were disclosed as competing interests. The source notes the remaining authors declared no commercial or financial relationships that could be construed as potential conflicts. Specific grant numbers and detailed conflict statements are reported in the original source.