Personality as Risk and Resilience in Physical Health

Research on the association between personality characteristics and subsequent physical health has produced several consistent findings and identified other tentative relationships. Chronic anger/hostility and neuroticism/negative affectivity are the best established personality risk factors for poor health. Optimism, social dominance, and other traits also appear to influence risk. Several mechanisms have been identified as possibly underlying these effects, but few have been evaluated definitively. Future research may be well served by incorporation of concepts and methods from current personality research.

Interpersonal circumplex descriptions of psychosocial risk factors for physical illness: application to hostility, neuroticism, and marital adjustment

Personality risk factors for physical illness are typically studied individually and apart from risk factors reflecting the social environment, potentially fostering a piecemeal understanding of psychosocial influences on health. Because it can be used to describe both personality and social relationship processes, the interpersonal circumplex (IPC) provides an integrative approach to psychosocial risk. In 301 married couples we examined IPC correlates of 3 risk factor domains: anger, hostility, and aggressiveness; neuroticism; and marital adjustment. Risk factors displayed IPC locations ranging from hostile dominance (e.g., verbal aggressiveness, marital conflict) to hostility (e.g., anger) to hostile submissiveness (e.g., anxiety, depression); protective factors (marital satisfaction and support) reflected warmth or friendliness in the IPC. Similar descriptions were found using self-reports and spouse ratings of IPC dimensions, indicating that interpersonal styles associated with risk factors do not simply reflect common method variance. Findings identify interpersonal processes reflecting low affiliation or high hostility as a common component of risk and indicate distinctions among risk factors along the dominance dimension.

The relationship between social status and atherosclerosis in male and female monkeys as revealed by meta-analysis

More than 25 years ago our laboratory reported sex-dependent relationships between social status and coronary artery atherosclerosis among cholesterol-fed cynomolgus monkeys (Macaca fascicularis) maintained in social groups of four to six animals each. Dominant males developed more atherosclerosis than subordinates, but only if housed in recurrently reorganized social groups. In contrast, dominant females developed significantly less atherosclerosis than subordinates, irrespective of social setting. Although we have continued to study these associations, no confirmatory investigations have been reported by other laboratories or using other atherosclerosis-susceptible monkey species. Accordingly, we conducted a meta-analysis of all relevant data sources developed in our laboratory since 1982 to determine whether the originally reported relationships between social status and atherosclerosis reflected robust associations. The sentinel (first) studies were composed of 16 females and 27 males. The current meta-analysis encompassed 419 animals (200 females and 219 males) derived from 11 separate investigations. The results confirmed that, among males, dominant individuals developed more extensive atherosclerosis than subordinates when housed in recurrently reorganized (unstable) social groups in which an estrogen-implanted female was also present. Dominant males in stable social groups tended to have less atherosclerosis than similarly housed subordinates, but this effect was not significant. On the contrary, we found that dominant females developed reliably less atherosclerosis than subordinates.

Personality and risk of physical illness

Several personality characteristics have been linked in multiple well-designed prospective studies to subsequent physical health outcomes, such as longevity and the development and course of cardiovascular disease. The evidence is strongest for negative affectivity/neuroticism, anger/hostility and related traits, and optimism. Models of mechanisms underlying these associations have emphasized physiological effects of stress, exposure to stressors, and health behavior. Preliminary evidence supports the viability of some mechanisms, but formal mediational tests are lacking. In addition to addressing limitations and inconsistencies in this literature, future research should address developmental aspects of these psychosocial risk factors, contextual moderators of their health effects, and intervention applications in the prevention and management of disease. In these efforts, greater incorporation of concepts and methods in the structural, social-cognitive, and interpersonal perspectives in the field of personality are needed.

The serotonin transporter: sequence variation in Macaca fascicularis and its relationship to dominance

Specific genotypes of the rhesus monkey and human serotonin transporter gene (SERT) promoter region are associated with personality traits and serotonergic activity. However, the most commonly studied promoter polymorphism (5-HTTLPR) is monomorphic in many other monkey species. To date, no systematic search for alternative potentially functional polymorphisms across the remaining coding parts of the gene has been undertaken in other primate species, despite the crucial role SERT plays in modulating serotonergic tone. We investigated whether sequence variation in this gene is associated with social rank and serotonin metabolite (5-HIAA) differences in 524 cynomolgus macaques. Sequence variation and extent of linkage disequilibrium (LD) across the regulatory and coding regions were initially characterized in 92 macaques. The exons and promoter contained 28 polymorphisms, more than double that recorded for human SERT. In further contrast to humans, the macaque SERT showed no significant LD. Potentially functional polymorphisms were genotyped in all animals. No individual variants or haplotypes were significantly associated with social rank or 5-HIAA concentrations; however, certain serotonin transporter diplotypes may modulate acquisition of dominance status.

Age, rank, and personality effects on the cortisol sedation stress response in young chimpanzees

Primates and other mammals exhibit a glucocorticoid response to somatic and psychosocial stressors. The pattern and degree of response varies both within and between species, but the factors affecting within-species variability have rarely been considered. Here we describe the 90-min serum cortisol response of 14 juvenile and adolescent chimpanzees to the stress of sedation with ketamine hydrochloride. We show age differences in both baseline cortisol and time of peak cortisol, with younger individuals (ages 4-5 years) showing higher baseline levels and an earlier peak response than older individuals (ages 8-9 years). However, we found no sex or rank-related differences in any of the sedation measures: baseline cortisol, cortisol peak time, peak cortisol level, or cortisol change from baseline. We also examined the relationship between these sedation stress measures and behavioral style score, and found that individuals scoring high in the "mellow" behavioral style component showed a greater stress response than individuals scoring lower in this component. Future studies should consider the role of individual differences in age and personality in the cortisol response to stress.

Psychosocial influences on the development and course of coronary heart disease: current status and implications for research and practice

Psychosocial characteristics predict the development and course of coronary heart disease (CHD). In this review, the authors discussed human and animal research on psychophysiological mechanisms influencing coronary artery disease and its progression to CHD. They then reviewed literature on personality and characteristics of the social environment as risk factors for CHD. Hostility confers increased risk, and a group of risk factors involving depression and anxiety may be especially important following myocardial infarction. Social isolation, interpersonal conflict, and job stress confer increased risk. Psychosocial interventions may have beneficial effects on CHD morbidity and mortality, although inconsistent results and a variety of methodological limitations preclude firm conclusions. Finally, they discussed implications for clinical care and the agenda for future research.

Status, stress, and atherosclerosis: the role of environment and individual behavior

Atherosclerosis induced by moderate hyperlipoproteinemia in group-housed cynomolgus monkeys differs significantly between animals of dominant and subordinate social status. The nature of this association also varies by sex, and in males, by stability of the social environment. Dominant males develop more extensive atherosclerosis than subordinates when housed in unstable, but not stable, social groups; in contrast, subordinate females develop greater atherosclerosis than dominants, and do so irrespective of the conditions of social housing. Experimental investigations reveal that the first of these associations (males) is mediated by concomitant sympathoadrenal activation and the second (females) by ovarian impairment associated with the stress of social subordination. We believe our findings offer clues to the neuroendocrine mediation of behavioral influences on coronary artery disease in humans. This is particularly true where these influences reflect asymmetries in the power or status relationships among individuals within similar social environments, or when dimensions of temperament or disposition give rise to such relationships. We propose that these data also may be informative regarding the pathophysiological sequelae of social stratification (in which disease incidence varies by class membership within populations), but only where social environments engendered by class inequalities exacerbate status-dependent behavioral differences among individuals within communities of associates.