The lonely brain: evidence from studying patients with penetrating brain injury

ABSTRACT

Loneliness is perceived as social isolation and exclusion. The neural substrate of loneliness has been investigated with functional neuroimaging; however, lesion-based studies and their associated outcomes are needed to infer causal involvement between brain regions and function. Here, we applied voxel-based lesion-symptom mapping (VLSM) analyses to investigate the causal role of brain lesions on self-report of loneliness (UCLA Loneliness Scale) in a unique sample from the Vietnam Head Injury Study, including veterans with penetrating traumatic brain injuries (pTBI) (n = 132) and healthy controls (HCs) (n = 35). Our results revealed that the right anterior insula (AI) and right prefrontal cortex (PFC) are key brain regions underpinning loneliness perception. Individuals with selective lesions to the right AI and right PFC were less likely to report loneliness compared to patients with selective lesions to the posterior cortex and HCs. Therefore, it appears that lesions to key regions involved in processing social pain act to lower the perception of loneliness. Reporting loneliness was associated with executive dysfunction, apathy, disinhibition, and lower life satisfaction. In conclusion, the reported findings broaden our understanding of how loneliness is processed in the social brain, and how behavioral and cognitive factors can influence this perception.

KEYWORDS:

• Loneliness
• prefrontal cortex
• anterior insula
• social cognition
• brain injury

Acknowledgments

We are grateful to our Vietnam veterans for their dedicated participation in the study. We thank J. Solomon for his help in developing with ABLe toolbox, as well as V. Raymont, S. Bonifant, B. Cheon, C. Ngo, A. Greathouse, K. Reding, and G. Tasick for testing and evaluating participants. We would also like to thank the National Naval Medical Center and the National Institute of Neurological Disorders and Stroke for providing support and facilities. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Navy, the Department of Defense, or the U.S. Government.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

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Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This research was also partly supported by the Therapeutic Cognitive Neuroscience Fund (B.G.), the Julius N. Frankel Foundation, and the Smart Family Foundation of New York.