In the Midst of a Pandemic, Introverts May Have a Mortality Advantage

Abstract

Extroverts may enjoy lower mortality than introverts under normal circumstances, but the relationship may be different during an airborne pandemic when social contact can be deadly. We used data for midlife Americans surveyed in 1995-96 with mortality follow-up through December 31, 2020 to investigate whether the association between extroversion and mortality changed during the COVID-19 pandemic. We hypothesized that excess mortality during the pandemic will be greater for extroverts than for introverts. Results were based on a Cox model estimating age-specific mortality controlling for sex, race/ethnicity, the period trend in mortality, and an additional indicator for the pandemic period (Mar-Dec 2020). We interacted extroversion with the pandemic indicator to test whether the relationship differed between prepandemic and pandemic periods. Prior to the pandemic, extroversion was associated with somewhat lower mortality (HR=0.93 per SD, 95% CI 0.88-0.97), but the relationship reversed during the pandemic: extroverted individuals appeared to suffer higher mortality than their introverted counterparts, although the effect was not significant (HR=1.20 per SD, 95% CI 0.93-1.54). Extroversion was associated with greater pandemic-related excess mortality (HR=1.20/0.93=1.29 per SD, 95% CI 1.00-1.67). Compared with someone who scored at the mean level of extroversion, mortality rates prior to the pandemic were 10% lower for a person who was very extroverted (i.e., top 12% of the sample at Wave 1), while they were 12% higher for someone who was very introverted (i.e., 11 ^th percentile). In contrast, mortality rates during the pandemic appeared to be highe r for very extroverted individuals (HR=1.15, 95% CI 0.77-1.71) and l ower for those who were very introverted (HR=0.70, 95% CI 0.43-1.14) although the difference was not significant because of limited statistical power. In sum, the slight mortality advantage enjoyed by extroverts prior to the pandemic disappeared during the first 10 months of the COVID-19 pandemic. It remains to be seen whether that pattern continued into 2021-22. We suspect that the mortality benefit of introversion during the pandemic is largely a result of reduced exposure to the risk of infection, but it may also derive in part from the ability of introverts to adapt more easily to reduced social interaction without engaging in self-destructive behavior (e.g., drug and alcohol abuse). Introverts have been training for a pandemic their whole lives.

Figure 1.. Hazard ratios for extroversion from model predicting age-specific mortality during prepandemic (1995 through Feb 2020) versus pandemic (Mar-Dec 2020) periods

Note. Based on a Cox model that uses age as the time metric and adjusts for sex, race/ethnicity, the linear period trend in mortality decline (prior to the pandemic), the main effects for all 5 personality traits, a dichotomous indicator for the pandemic period (Mar-Dec 2020), and an interaction between the extroversion score and the pandemic indicator, which tests whether the effect of extroversion differed between the prepandemic and pandemic periods.

Figure 2.. Fully-adjusted percentage surviving from age 25 to 85 by level of extraversion during prepandemic (1995 through Feb 2020) versus pandemic (Mar-Dec 2020) periods

Note: Estimates are based on Model 3 (Table 2) where the year is set to 2020, period is set to either prepandemic (Jan-Feb) or pandemic (Mar-Dec), and the extraversion score is fixed at the 11^th percentile (i.e., scored 2.4 out of 4, defined as very introverted) or the top 12% of the distribution (i.e., scored 4 out of 4, defined as very extroverted). All other covariates (i.e., sex, race/ethnicity, and the other four personality traits) are fixed at the mean for the sample.