The last couple of decades of research has provided a strong foundation for what seems intuitive; that our social connections and relationships matter, and they matter to the risk of cardiovascular disease and even all-cause mortality. One of the largest meta-analyses to date was published in 2010 in PLOS Medicine, and included 148 studies and over 300,000 participants. This analysis found a substantial 50% increase in odds of survival as a function of social relationships; this increased to over 60% when complex measures were used to assess social integration (vs. binary yes/no questions), as well as when high vs. low social support was compared. Put in perspective, this effect is greater than that associated with typical risk factors. For example, it is larger than the effect comparing lean vs. obese BMI, physical activity, alcohol consumption, etc., with low social support approximating the risk of smoking on a daily basis. Although causality cannot be determined, initial health status did not modulate the effect of social relationships on mortality, suggesting a directional effect. Additionally, the overall effect of social relationships on mortality appears to be a general one; in addition to initial health status, age, gender, and cause of death did not affect the overall effect.
Of course, we have many types of relationships, including intimate or romantic relationships, as well as those that reflect integration into society, such as personal ties to family and friends and social ties to community. In an analysis published in 2018 in Scientific Reports, researchers examined several components of social connections, including marriage/partnerships, social contacts, religious participation, and membership in clubs/organizations. As above, social isolation was associated with a 60-70% increase in all-cause mortality when comparing the most to the least isolated individuals, after multivariate adjustment (in both men and women). Among the components, not having a partner was the biggest risk factor, associated with a 50% increase in men and a 70% increase in risk for women.
However, partnerships can be associated with both positive and negative influences on cardiovascular risk. In a review published in 2022 in Current Cardiology Reports, the role of intimate relationships in the development and unfolding of coronary heart disease was detailed, describing 3 general categories of influence which each have substantial research; direct physiological effects of partnerships which are mediated through stress and emotion, an influence on other health behaviors (e.g., eating patterns, smoking, etc.), and how intimate relationships mediate the adaptation to acute and chronic disease care. While generally intimate relationships have a protective effect, “strain” (such as recurring conflict and dissatisfaction) and disruption (i.e., separation, divorce) can exacerbate risk. For example, strain in a relationship is associated with an increased risk for incident heart disease, more severe atherosclerosis, and a worse prognosis, and similarly, divorce is associated with a greater risk of incident heart disease and poorer outcomes, with a range of 30-90% increase in risk cited in this paper. This strongly suggests that an assessment of social connectedness, particularly the quality of intimate relationships, should be an essential component of cardiovascular risk evaluation.
One important component to consider when assessing the quality of intimate relationships is perceived partner responsiveness (PPR), “the extent to which individuals believe that their romantic partners care about, understand, and validate their thoughts and feelings”, as described in a 20-year longitudinal study published in Psychosomatic Medicine. PPR is thought to down-regulate negativity and increase feelings of security, helping to satisfy the needs of belongingness and bonding; in other words, it may help to soothe feelings of negativity while supporting positive ones. This study was part of the National Survey of Midlife Development in the United States (MIDUS), which included over 1200 adults assessed at 3 different points in time. In addition to PPR, affective reactivity was also assessed; positive and negative affect reactivity refers to reactions to daily stresses/events versus chronic ones. For example, negative affect reactivity includes feelings like being nervous, worthless, hopeless, etc., while positive affect includes feeling cheerful, proud, satisfied, etc., and these (positive and/or negative) may have some predictive value for long-term outcomes. This study found robust associations between changes in PPR and overall mortality, as well as negative affect reactivity and mortality. Perhaps the biggest takeaway is that changes in PPR over time influence longevity, and it may be that the ability of PPR to soothe the negative reactions to daily stresses is a likely mechanism. Improving PPR among couples seems like a therapeutic approach with the potential for substantial benefits.
Lastly (on a more light-hearted note), a study of young couples has encouraging implications. Among 63 heterosexual couples, men’s overnight heart rates varied not as a function of their own daytime feelings, but as a function of their partners. Specifically, greater feelings of annoyance and lower perceived feelings of closeness among women were linked to a higher heart rate among the men, independently of their daytime rates. While there are many conclusions one might draw from this study, it is heartening to have some level of evidence for the ability of one partner’s feelings of closeness to not only affect the other, but to modulate the actual beating of their heart. Happy Valentine’s Day!