The study was renewed in fiscal year (FY) 1997 to expand the primary focus on hostility to include a set of psychosocial, behavioral, and biological characteristics that increased coronary heart disease risk and appeared to cluster in certain individuals and groups, especially those low in socioeconomic status (SES). Subproject 1 examined in approximately 360 subjects the synergistic effects of SES and psychosocial risk factors such as depression, hostility, and social isolation on biological and behavioral factors suspected or known to contribute to atherogenesis. Subproject 2 evaluated the role of the central nervous system serotonin function as a potential mediator of the clustering of health-damaging psychosocial and biobehavioral characteristics in the same individuals and low SES groups. Subproject 3, the Psychosocial Risk for Cardiovascular Disease in Youth Project (PRCVDYP), used three ongoing general population studies of youth as a basis for examining the development of psychosocial risk for cardiovascular disease. The investigators hypothesized that low SES youth would exhibit, in addition to increased levels of the psychosocial and behavioral risk factors under study, increased sympathetic nervous system tone and reactivity to mental challenge, as well as decreased peripheral nervous system tone. They also hypothesized that depression, social isolation, and harsh parenting will interact with low SES to increase cardiovascular disease risk. Subproject 4 used a rat model to investigate early experience, serotonin and adult function.