Studies of psychosocial influences on coronary artery atherogenesis in cynomolgus monkeys

The cynomolgus macaque provides a suitable primate model for studying how psychosocial factors contribute to coronary artery atherogenesis. Important interactions with diet, sex, and behaviorally elicited cardiovascular reactivity are described.     

Neuropsychological correlates of hypertension: review and methodologic considerations.

Essential hypertension is a chronic disorder having many potential physical and behavioral sequelae. This article evaluates the impact of hypertension on neuropsychological test performance. First, cross-sectional and longitudinal studies that examine the neuropsychological correlates of hypertension are reviewed. In general, hypertensives are found to perform more poorly than normotensives, particularly on tests of memory, attention, and abstract reasoning, and less consistently on tests of perception, constructional ability, mental flexibility, and psychomotor speed. Next, the influence of variables that may moderate relationships between hypertension and neuropsychological performance--such as age, education, and medication usage--are examined. Finally, potential mechanisms, both physiological and psychological, underlying associations between hypertension and neuropsychological performance are discussed.     

Role of feedback in voluntary control of heart rate.

The relative effectiveness of biofeedback techniques on the voluntary control of heart rate was examined by randomly assigning 32 Ss to one of four feedback conditions in a bi-directional heart-rate control task: (1) no feedback, (2) binary feedback--S was signaled when an interbeat interval had changed in the correct direction, (3) "real-time," proportional feedback--S was provided information about the relative duration of successive interbeat intervals, and (4) numerical, proportional feedback--each interbeat interval was represented as a numeral indicating its relationship to pre-trial mean by direction and magnitude. Significant over-all heart-rate changes were evidenced for both increase and decrease directions, but no differences were found between the feedback conditions. While these data suggest that feedback may be a relatively insignificant factor in voluntary heart-rate control, it was recommended that further investigation examine the role of feedback within the context of other training, mediating and motivational variables.     

The nature of the association between diet and serum lipids in the community: a twin study.

Diet is commonly thought to be an environmental influence on serum lipid concentrations. This study evaluated whether total caloric and fat intake predict total cholesterol (TC), low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), and triglyceride (TRIG) concentrations for environmental, as compared with genetic, reasons among 137 monozygotic and 67 dizygotic young adult twins. When genetic influences were controlled by correlating differences between monozygotic co-twins, a significant association remained between diet and TC, LDL, and HDL, suggesting that these dietary and serum lipid measures correlate for environmental reasons. Twin structural equation modeling confirmed these results. Overall, these results provide additional support for the hypothesis that diet is an environmental influence on TC, LDL, and HDL.     

CHRONIC SOCIAL STRESS, AFFILIATION, AND CELLULAR IMMUNE RESPONSE IN NONHUMAN PRIMATES

Abstract ——We report the first experimental study of the effect of long–term (over 2 years) exposure to a stressor on cellular immune response Forty–three male cynomolgus monkeys were randomly assigned to stable or unstable social conditions for 26 months The proportion of time spent in affiliative behaviors was assessed by observations made twice weekly T–cell immune response (mitogen–stimulated cell proliferation) was assessed weekly for 3 weeks immediately following the 26–month manipulation The possibility that affiliative behavior represents an attempt to cope with social stress was supported by greater affiliation among animals m the unstable condition than in the stable condition Animals in the unstable condition also demonstrated relatively suppressed immune response More affiliative animals showed enhanced immune response, with the beneficial effects of affiliation occurring primarily among unstable animals The data are interpreted as consistent with the stress–buffering hypothesis, that IS, affiliation protects animals from the potentially pathogenic influences of chronic social stress     

Influence of age, sex, and family on Type A and hostile attitudes and behaviors.

We describe the influence of age, sex, and family on Type A and hostility indices that have been related to rates of coronary heart disease (CHD). The sample consisted of 120 girls and 95 boys (ages 6 to 18 years) and 141 women and 120 men (ages 31 to 62 years) from 142 families residing in an upper middle class community. Results showed little familial aggregation of Type A and hostility. Adults had higher Structured Interview (SI) Potential for Hostility ratings than did children, whereas children had higher Minnesota Multiphasic Personality Inventory (MMPI)-derived Hostility scores and SI Anger-In ratings than did adults. Male adults and male children had higher SI Potential for Hostility ratings and MMPI-derived Hostility scores than did their female counterparts. The heightened hostility of males may account, in part, for their heightened risk of CHD relative to females'.     

Anabolic-androgenic steroids: effects on social behavior and baseline heart rate

Examined the effects of anabolic-androgenic steroids (AS) on behavior, baseline heart rate (HR), and stress-induced HR responses. Twenty-four cynomolgus monkeys were assigned to four mixed social groups of both AS and sham control animals. For 2 months, AS-treated monkeys received biweekly injections of testosterone, and, on an identical schedule, the control animals were injected with a sham solution. Behavioral data revealed that AS disrupted the social milieu such that all dominant animals exhibited increases in dominant behavior and subordinates manifested increased submission. These changes returned to pretest levels 8 weeks following termination of the drug intervention. Affiliative behaviors decreased on the part of all animals as a function of AS and, with the exception of play behavior, failed to return to pretest levels after the 8-week period of recovery. AS created an increase in baseline HR, particularly among the dominant animals. Interestingly, the subordinate AS animals experienced a decrease in baseline HR response. AS had no apparent influence on stress-induced HR reactivity.