ECT-induced cognitive side effects are associated with hippocampal enlargement

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Electroconvulsive therapy (ECT) is a highly effective treatment for treatment-resistant depression.
• Cognitive side effects, particularly memory impairment, limit ECT's use.
• Neurobiological basis for ECT-induced cognitive deficits, especially hippocampal involvement, remains unclear.

Purpose of the Study:

• To investigate the relationship between ECT-induced hippocampal volume changes and cognitive side effects.
• To determine if hippocampal volume changes are associated with neurocognitive performance.
• To assess the generalizability of findings across different ECT protocols and patient cohorts.

Main Methods:

• Longitudinal magnetic resonance imaging (MRI) was used to measure hippocampal volume changes in two independent cohorts of patients undergoing ECT.
• Detailed neuropsychological testing assessed cognitive function before and after ECT.
• Longitudinal freesurfer algorithms (version 6.0) were employed for bias-free volume estimation.
• Exploratory analysis examined volume changes in 41 other brain regions.
• Cognitive data from healthy volunteers were analyzed to control for practice effects.

Main Results:

• ECT treatment robustly increased hippocampal volume in both cohorts (p < 0.001).
• Increased hippocampal volume correlated with worse neurocognitive T-score changes (r = -0.68, p = 0.005 in Cohort 1; r = -0.58, p = 0.04 in Cohort 2).
• Hippocampal enlargement was associated with cognitive deficits, independent of diagnosis, electrode placement, or number of sessions.

Conclusions:

• Hippocampal volume enlargement is a neurobiological correlate of cognitive side effects following ECT.
• Findings suggest that interventions aimed at mitigating hippocampal volume increase could improve ECT's side effect profile.
• This research provides a potential target for optimizing ECT efficacy and tolerability.