Online social integration is associated with reduced mortality risk

Abstract

Social interactions increasingly take place online. Friendships and other offline social ties have been repeatedly associated with human longevity, but online interactions might have different properties. Here, we reference 12 million social media profiles against California Department of Public Health vital records and use longitudinal statistical models to assess whether social media use is associated with longer life. The results show that receiving requests to connect as friends online is associated with reduced mortality but initiating friendships is not. Additionally, online behaviors that indicate face-to-face social activity (like posting photos) are associated with reduced mortality, but online-only behaviors (like sending messages) have a nonlinear relationship, where moderate use is associated with the lowest mortality. These results suggest that online social integration is linked to lower risk for a wide variety of critical health problems. Although this is an associational study, it may be an important step in understanding how, on a global scale, online social networks might be adapted to improve modern populations' social and physical health.

Keywords: health; longevity; social media; social networks; social support.

Fig. 1.

Facebook friends and relative mortality risk (all-cause mortality). This figure shows all-cause mortality estimates (points) by deciles of Facebook friend counts, by initiated (A) and accepted (B) Facebook friendships and adjusted for age, gender, device use, and length of time on Facebook. The vertical bars are 95% CIs, and the square at 1.0 is the reference category. (A) Initiated friendship: the subject sent a Facebook friendship request that was then accepted. (B) Accepted friendship: the subject received and accepted a friendship request. The x axis is the median number of Facebook friends in the decile, and the y axis is the relative mortality risk estimated in a Cox proportional hazard model. The two friendship categories were estimated separately due to high collinearity between them.

Fig. 2.

Mortality risk as a function of two social media activities. (A) All-cause mortality hazard ratio estimates for combinations of text-based activity (as measured by posting statuses) and photo-based activity (as measured by posting photos). (B) All-cause mortality hazard ratio estimates for combinations of text-based directed communications (as measured by posts with tags and messages sent) and photo-based directed communications (as measured by photo tags received). The x and y axes are the quantiles of activities shown in the labels (each tick shows the respective quantile median). Colors show risk of mortality at each combination (red is higher; blue is lower). Results were estimated in a Cox proportional hazard model with interacted indicators for each decile of activity (fewer than 10 categories where the number of users with 0 activity spanned more than one decile). To present similar relative hazard scales (where a hazard of 1.0 corresponds to an average risk), we used the [0,0] interaction quantile as the reference category in the undirected analysis (no photos, no statuses) and the [1, 1] interaction quantile as the reference category in the directed analysis (one sent post or message, one received photo tag). We smoothed the quantile estimates with an approximate Nadaraya–Watson kernel smoother set to a bandwidth of 0.9.

Fig. 3.

Cause-specific mortality risk as a function of various Facebook activities. (A) Cause-specific mortality hazard ratio estimates for Facebook friendships (total, initiated, and accepted counts). (B) Cause-specific mortality hazard ratio estimates for undirected activities (social media communications without a specific recipient). (C) Cause-specific mortality hazard ratio estimates for directed activities (social media communications with a specific recipient). Points indicate cause-specific morality risk estimates and vertical bars show 95% CIs. Actions by the subject are shown in purple, actions by the subject’s friend are shown in green, combined actions are shown in orange, circles denote friending activities, triangles denote text-based actions, and squares denote photo-based actions. All variables are logged (after adding one to the activity count), scaled by their SD (so that a unit change is an SD and comparable across activities), and centered at their means. The x axis is the cause of death (an extended table for more and more finely discriminated causes of death is included in SI Appendix), and the y axis is the relative mortality risk associated with a SD change in the relevant activity, estimated in a Cox proportional hazard model. All activity categories were estimated separately due to high collinearity among them. “P/M” here is an abbreviation for “posts and messages.”