Abnormal functional connectivity patterns in temporal lobe epilepsy-An international ENIGMA-epilepsy study.

Area of Science:

• Neuroscience
• Epilepsy Research
• Brain Network Analysis

Background:

• Temporal lobe epilepsy (TLE) affects multiple brain networks, with known alterations in resting-state networks (RSNs) crucial for higher cognitive functions.
• Understanding these network disruptions is key to addressing cognitive comorbidities and seizure propagation in TLE.

Purpose of the Study:

• To identify reproducible patterns of altered functional connectivity in TLE using a large, international cohort via the ENIGMA-Epilepsy project.
• To investigate alterations in whole-brain connectivity within and between major RSNs in TLE patients compared to healthy controls.

Main Methods:

• Analysis of resting-state functional MRI data from 442 individuals with TLE and 387 healthy adults across nine international centers.
• Examination of group differences in whole-brain connectivity across seven major RSNs, including the default mode network (DMN).
• Assessment of associations between connectivity patterns and clinical variables like age of seizure onset and disease duration.

Main Results:

• TLE patients exhibited significantly lower within-network connectivity (average 13.6% decrease) and higher between-network connectivity (average 129% increase) in non-limbic RSNs.
• These connectivity patterns were highly reproducible across all seven participating sites and most prominent in the DMN and visual networks.
• Connectivity alterations were largely independent of age of seizure onset or disease duration and showed minimal differences between left and right TLE.

Conclusions:

• The study provides robust evidence for widespread, consistent disruption of brain network organization in TLE across diverse geographical sites.
• Findings indicate reduced intra-network connectivity and increased inter-network connectivity as a hallmark of TLE.
• This network reorganization may underlie the cognitive impairments and seizure propagation patterns observed in individuals with TLE.