UCLA

Loneliness is widespread and has serious consequences for public health. Current loneliness interventions have focused on behavioral or psychological strategies to reduce loneliness. However, loneliness has profound effects on physiology that may be difficult to change behaviorally. Given the bidirectional relationship between loneliness and inflammation, one key biological pathway to target may be inflammation. Interestingly, there is evidence that loneliness as well as inflammation may inhibit certain positive interpersonal processes. Thus, it is possible that reducing inflammation in a lonely population may reduce loneliness and facilitate positive interpersonal processes. However, this possibility has not yet been tested.To test these hypotheses, we investigated whether a non-steroidal anti-inflammatory medication (naproxen) could reduce loneliness and promote positive interpersonal processes, including kindness, compassion, and positive social dynamics in a live social interaction. Healthy, middle aged participants (n = 80) currently experiencing high levels of loneliness were randomly assigned to either take naproxen or a placebo daily for two weeks. Self-report measures of loneliness and positive interpersonal processes were collected at baseline, post-intervention, and two weeks post-intervention. At pre- and post-intervention, participants additionally completed a compassion induction and social affiliation experimental task. Results revealed that naproxen (vs. placebo) did not directly reduce loneliness but did increase feelings of compassion in response to the compassion task. Moreover, baseline depressive symptoms moderated the effect of the intervention on loneliness such that those experiencing greater depressive symptoms at baseline showed the greatest decreases in loneliness, as well as the greatest increases in certain positive interpersonal processes (emotional support-giving, reduced negative affect pre-interaction, and affiliative behavior during a social interaction). Furthermore, reductions in loneliness in the high-baseline depression group were maintained at two weeks post-intervention. This is the first known randomized controlled trial to investigate a pharmacological intervention for loneliness, and sheds light on one physiological pathway that may be helpful in reducing loneliness and facilitating connection in those experiencing loneliness and depression.