Multilayer MEG functional connectivity as a potential marker for suicidal thoughts in major depressive disorder

Highlights

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  Generalized slowing of connectivity was seen in those with MDD vs healthy subjects.

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  Slowing from alpha/beta-mediated to delta/theta-mediated connectivity was observed.

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  Connectivity strength and suicidal thoughts were linked in MDD subjects.

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  “Hub” regions in the brain potentially underlying suicidal thoughts were identified.

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  Connectivity differed between those with high suicidal thought scores and controls.

Abstract

Major depressive disorder (MDD) is highly heterogeneous in its clinical presentation. The present exploratory study used magnetoencephalography (MEG) to investigate electrophysiological intrinsic connectivity differences between healthy volunteers and unmedicated participants with treatment-resistant MDD. The study examined canonical frequency bands from delta through gamma. In addition to group comparisons, correlational studies were conducted to determine whether connectivity was related to five symptom factors: depressed mood, tension, negative cognition, suicidal thoughts, and amotivation. The MDD and healthy volunteer groups did not differ significantly at baseline when corrected across all frequencies and clusters, although evidence of generalized slowing in MDD was observed. Notably, however, electrophysiological connectivity was strongly related to suicidal thoughts, particularly as coupling of low frequency power fluctuations (delta and theta) with alpha and beta power. This analysis revealed hub areas underlying this symptom cluster, including left hippocampus, left anterior insula, and bilateral dorsolateral prefrontal cortex. No other symptom cluster demonstrated a relationship with neurophysiological connectivity, suggesting a specificity to these results as markers of suicidal ideation.