외로움의 신경생물학: fMRI 기반 대규모 뇌 네트워크 기능적 연결성에 대한 내러티브 리뷰

초록

This narrative review synthesizes functional magnetic resonance imaging (fMRI) evidence on functional connectivity within largescale brain networks implicated in loneliness. Loneliness is a complex neurobiological condition that extends beyond transient emotional states, exerting profound effects on psychological, cognitive, and physical health. It is a significant risk factor for depression, anxiety, suicidal ideation, cognitive decline, reduced quality of life, social dysfunction, and increased all-cause mortality. Neuroimaging evidence indicates that loneliness involves disrupted functional connectivity across large-scale brain networks, suggesting shared, transdiagnostic neural mechanisms. Specifically, we synthesize human fMRI findings to delineate loneliness-related alterations in network-level connectivity and compare these alterations with patterns observed in depression, anxiety, and suicidal ideation. Loneliness is consistently linked to altered functional connectivity across six core systems—sensory circuit, salience network, attention network, default mode network, cognitive control network, and reward circuit. These alterations reflect imbalances in perceptual integration, threat detection, attention regulation, self-referential processing, cognitive control, and social reward sensitivity, and collectively may constitute a shared neural vulnerability across multiple mental health conditions. Loneliness may represent a chronic neurobiological state characterized by pervasive functional dysconnectivity. Characterizing these patterns is critical for advancing transdiagnostic models of mental health vulnerability and for guiding the development of network-targeted interventions for loneliness.

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