Inflammation and social experience: an inflammatory challenge induces feelings of social disconnection in addition to depressed mood.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 20043983 · doi:10.1016/j.bbi.2009.12.009
What was done
Participants were randomly assigned to receive an inflammatory challenge with endotoxin or a placebo. Proinflammatory cytokines (IL-6 and TNF-alpha) were measured at baseline and hourly for 6 hours. Participants completed hourly self-report ratings of sickness symptoms ("fatigue"), social disconnection ("I feel disconnected from others"), and depressed mood ("unhappy").
What was found
The abstract reports no numerical values, effect sizes, or p-values. It states that endotoxin administration led to statistically significant increases from baseline in IL-6 and TNF-alpha levels, feelings of social disconnection, and depressed mood. Controlling for increases in social disconnection eliminated the relationship between endotoxin exposure and depressed mood.
Why it matters
This trial experimentally demonstrates that acute systemic inflammation directly induces subjective feelings of social disconnection, identifying social psychological processes as potential mediators between cytokine activity and depressed mood.
Limits
The abstract omits the sample size, participant demographics, baseline health characteristics, and exact quantitative statistics. The study tested an acute 6-hour endotoxin challenge, which may not generalize to chronic low-grade inflammation, and relied on brief single-item self-report measures for psychological constructs.
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