How does loneliness "get under the skin" to become biologically embedded?

Area of Science:

• Psychoneuroimmunology
• Epigenetics
• Public Health

Background:

• Loneliness is associated with adverse health outcomes in cardiovascular, inflammatory, metabolic, and cognitive systems.
• Existing research does not fully explain the mechanisms behind loneliness-related health risks, highlighting a public health concern.

Purpose of the Study:

• To review the evidence for direct, indirect, and artifactual pathways through which loneliness impacts health.
• To emphasize emerging research on epigenetic modifications as a mechanism for biological embedding of loneliness.

Main Methods:

• Scoping review of existing literature.
• Examination of evidence for direct health impacts, indirect effects via behaviors, and artifactual associations.
• Focus on epigenetic mechanisms, including methylation and transcription factor activity.

Main Results:

• Evidence suggests multiple pathways link loneliness to health, including direct physiological effects and indirect behavioral influences.
• Epigenetic modifications, particularly through hypothalamic-pituitary-adrenal axis disruptions, are a promising but complex area of study.
• Significant knowledge gaps remain regarding the direct causal influence of loneliness on physiological changes.

Conclusions:

• Further research is required to elucidate how psychosocial stress, like loneliness, translates into physiological changes.
• Causally informative study designs, such as twin/family studies and longitudinal diary studies, are needed to address remaining questions.
• Understanding the biological embedding of loneliness is crucial for developing effective public health interventions.