Self-Rated Health and Mortality: Moderation by Purpose in Life.

Poor self-rated health consistently predicts reduced longevity, even when objective disease conditions and risk factors are considered. Purpose in life is also a reliable predictor of diverse health outcomes, including greater longevity. Given prior work in which we showed that purpose in life moderated the association between chronic conditions and health-related biological factors, the aim of the current study was to examine the role of purpose in life in moderating the relationship between subjective health and mortality. We also examined potential differences in these associations by race/ethnicity. Data were from two large national longitudinal studies-the Health and Retirement Study (HRS) and the Midlife in the United States (MIDUS) study-with a 12- to 14-year follow-up period for mortality estimates. Results of logistic regression analyses showed that purpose in life and self-rated health were both significantly positively associated with longevity, and that purpose in life significantly moderated the relationship between self-rated health and mortality. Stratified analyses showed similar results across all racial/ethnic groups, with the exception of Black MIDUS participants. These results suggest that greater purpose in life may provide a buffer against the greater probability of mortality associated with poor subjective health.

Childhood maltreatment exposure and physical functional limitations in late adulthood: examining subjective sleep quality in midlife as a mediator.

Objective: The present study had three major aims: 1) To identify sub-groups of adults with differing combinations of childhood maltreatment exposures, 2) to understand the association of childhood maltreatment sub-group membership with subjective sleep quality in midlife, and 3) to assess poor sleep quality in midlife as a mechanism between childhood maltreatment sub-group membership and physical functional limitations in late adulthood. Design: Data come from the Biomarker project of the Midlife Development in the United States study (n = 1251). Outcome measures: The Pittsburgh Sleep Quality Index (Buysse et al., 1989) was used to assess sleep quality in midlife. Functional limitations in late adulthood were measured using a version of the SF-36 (Brazier et al., 1992). Results: Two vulnerable childhood maltreatment sub-groups emerged (Physical and Emotional Maltreatment Sub-group, n = 49, and Sexual Abuse Sub-group, n = 105) and a normative sub-group (n = 1087; low exposure to childhood maltreatment). Poor sleep quality in midlife mediated the association between both maltreatment sub-groups and functional limitations in late adulthood. Conclusion: Results highlight the role of sleep in linking childhood maltreatment with functional impairments in adulthood and offer a potential target for interventions to improve quality of life in older adults.

Moderation of the Association Between Chronic Medical Conditions and Functional Limitations Over Time by Physical Activity: Effects of Age.

BACKGROUND: Age-related accumulation of chronic medical conditions increases disability in older adults. Physical activity potently combats chronic conditions and disability. However, it is unclear whether activity maintenance alleviates the effects of chronic conditions on disability and if this buffering effect differs with age. This study examined whether long-term physical activity can forestall functional limitations in the face of accumulating chronic conditions among middle-aged and older adults. METHODS: Participants (n = 2,119; 54.7% female) were from the Survey of Midlife Development in the United States. Self-reported physical activity, number of chronic conditions, and functional limitations were obtained across 18-20 years. Functional limitations were regressed against the change in chronic conditions, physical activity, and their interaction over time in a multilevel model of change. Baseline age was added as an additional moderator. RESULTS: Faster accumulation of chronic conditions [B(SE) = 2.08(0.32), p < .001] and steeper declines in activity [B(SE) = -2.29(0.41), p < .001] were associated with greater increases in functional limitations over time. Among those with faster-than-average increases in conditions, those who maintained activity had a slower progression of functional limitations, compared to those whose activity declined more rapidly [B(SE) = -11.18(3.96), p = .005]. Baseline age moderated the buffering effect of activity maintenance; older adults were protected against functional limitations only when conditions accumulated slowly [B(SE) = 0.23(0.08), p = .005]. CONCLUSION: This study provides evidence for an age-dependent buffering effect of activity maintenance on the longitudinal relationship between chronic conditions and functional limitations. Intervention strategies using physical activity to forestall disability should target midlife adults and consider the rate of condition accumulation.

Individuals' perceptions of social support from family and friends are associated with lower risk of sleep complaints and short sleep duration.

OBJECTIVE: To examine whether individuals' perceptions of social support (SS) from partners, other family members, and friends are associated with risk of sleep complaints and short sleep duration. METHODS: A cross-sectional and prospective study with 1,688 community dwelling adults from the Retirement and Sleep Trajectories study. Four annual, self-administered questionnaires were mailed to participants in the year 2010-2014. Self-reports of individuals' perceptions of SS were obtained at the baseline survey. Sleep quality and duration were self-reported on each of the four surveys over the follow-up. Associations were examined with mixed-effect models, controlling for confounders. RESULTS: In fully adjusted analyses, compared with those reporting low SS from their partner, the risk of reporting more than 1 sleep symptom was significantly lower among those with intermediate (relative risk, RR = 0.68; 95% confidence interval, CI = 0.53-0.87) and high SS (RR = 0.61; 95% CI=0.48-0.77). Similarly, relative to those with low SS, those reporting high SS from family (RR = 0.74; 95% CI = 0.57-0.94) and friends (RR = 0.73; 95% CI = 0.58-0.92) had lower risk of having more than 1 sleep symptom. Compared with those with low, intermediate (RR = 0.70; 95% CI = 0.52-0.96), and high SS (RR = 0.63; 95% CI = 0.48-0.84) from partners, intermediate (RR = 0.76; 95% CI = 0.59-0.97) and high SS (RR = 0.69; 95% CI = 0.51-0.92) from family and high SS (RR = 0.74; 95% CI = 0.56-0.99) from friends were associated with lower risk of short sleep (≤6 h). CONCLUSION: The perception of higher SS from relatives and friends is independently associated with lower risk of poor sleep quality and short sleep duration. Future research and intervention studies should test whether strengthening social relationships can positively effect sleep health.

Multimorbidity, inflammation, and disability: a longitudinal mediational analysis.

BACKGROUND: Using longitudinal data from the Survey of Mid-Life Development in the United States, this study examined the role of systemic inflammation in mediating the link between multimorbidity and increases in and onset of functional limitations over a 17-19 year follow-up period. METHODS: Participants completed questionnaire assessments of chronic conditions and functional limitations. Interleukin-6, C-reactive protein, and fibrinogen were assayed in serum. Structural equation models were used to predict increases in and onset of functional limitations associated with baseline multimorbidity status; mediation by inflammation was also determined. RESULTS: Multimorbidity (versus 0-1 conditions) predicted more functional limitations and greater odds of onset of limitations over time. Significant indirect effects showed that inflammation partially mediated the link between multimorbidity and changes in, but not onset of, limitations. DISCUSSION: These results show that inflammation, a nonspecific marker of multiple disease conditions, explains in part the degree to which multimorbidity is disabling.

Relative sensitivity of cortisol indices to psychosocial and physical health factors.

OBJECTIVE: Regulation of cortisol under resting conditions is widely used to assess physical and psychological status, but due to the diversity of possible assessments (e.g., cumulative levels; diurnal patterns), considering one or a few at a time hampers understanding and interpretation. Moreover, most studies of cortisol regulation focus on negatively-valanced experiences. This study examined the inter-correlations among cortisol indices and their relative contribution to the explained variance in diverse psychosocial and health factors, including positive functioning. METHODS: Data are from midlife and older adults (N = 513; 47.2% male). Cortisol was assessed in urine (overnight) and saliva (at rest and over 4 consecutive days). Positive and negative psychosocial and health factors were assessed by self-report. In addition to examining associations among cortisol indices, relative weight analysis was used to determine which indices were most robustly linked to specific psychosocial factors. RESULTS: Inter-correlations among indices were weak-to-moderate, suggesting that they measure different aspects of hypothalamic-pituitary-axis activity. Overall variance in psychosocial and health factors (R2) explained by the cortisol indices ranged from 0.01 to 0.07. Of this explained variance, relative weight analysis showed that waking cortisol contributed most to the variance in hedonic well-being (32.1%-38.2%), bedtime cortisol to depression-related factors (32.1%-46.9%), the cortisol awakening response to eudaimonic well-being (35.8%-50.5%), cortisol slope to perceived stress (29.2%), and urinary cortisol to physical factors (38.5% and 62.7%). CONCLUSIONS: Positive and negative factors were related to largely non-overlapping cortisol indices. This study illuminates nuanced associations among cortisol indices and diverse aspects of mental and physical health, facilitating thoughtful examination of the complex role of hypothalamic-pituitary-axis activity in health.

The Association of Psychological Well-Being with Disablement Processes in a National Sample.

OBJECTIVE: Objectives were to explore subgroups of individuals with differential disability trajectories and evaluate the protective effects of psychological well-being (i.e. hedonic and eudaimonic) in the presence of multiple disease conditions (or multimorbidity) and sociodemographic disadvantages. METHODS: Data come from the prospective longitudinal cohort study the Midlife Development in the United States (n = 3,904). Three waves of data spanning a 20-year period were used to identify subgroups with different disability trajectories. Subgroup membership was then modelled as a function of psychological well-being assessed at wave 1 of the study using multinomial logistic regression. RESULTS: Three unique groups were identified: a normative group with initially low and slowly increasing levels of disability; a group with high levels of disability that was stable over time; and a group with moderate initial levels of disability that increased over time. Hedonic well-being at wave 1 was associated with membership in the risk groups relative to the normative group. CONCLUSION: Individuals may follow one of three disability pathways mostly as a function of multimorbidity. However, hedonic well-being was associated with having an advantageous disability trajectory regardless of multimorbidity status. Cultivating psychological well-being may improve disability outcomes in aging individuals.

Well-being and Long-term Physical Activity Participation in Midlife Adults: A Latent Class Analysis.

Background: Despite the benefits of physical activity, a large majority of adults fail to get the recommended amount of regular exercise, and interventions to increase physical activity typically achieve only temporary improvements. The potential contribution of positive psychological functioning to the maintenance of physical activity has not been widely examined. Purpose: To test the hypothesis that psychological well-being would increase the likelihood of sustained physical activity in adults using a person-centered approach with longitudinal data. Methods: Participants (N = 2,214) were from the longitudinal Survey of Midlife Development in the United States (MIDUS). Continuous latent variables representing physical activity at three waves of MIDUS were used to partition respondents into distinct (categorical) classes based on longitudinal activity profiles. Results: Latent class analyses identified three distinct physical activity profiles: sustained, consistently low, and declining activity (the normative class). Multinomial logistic regression analyses showed that the odds of membership in the sustained activity class were significantly higher for those with higher eudaimonic well-being (OR = 1.08 [1.03-1.13], p = .001), after adjustment for diverse covariates. Supplemental analyses revealed similar associations for specific subdomains of eudaimonic well-being. Conclusion: This study provides evidence that greater well-being may help sustain physical activity in the long term. These results suggest that improving well-being may be a useful addition to interventions aimed at increasing long-term physical activity participation.

The Role of Affect on Physical Health Over Time: A Cross-Lagged Panel Analysis Over 20 Years.

BACKGROUND: While previous studies have investigated the interplay between affect and health (1) over an extended period of time, (2) in a representative population, and (3) while modelling positive and negative affect simultaneously, no single study has done all three at once. METHODS: The present study accomplishes this by sampling adults from the Midlife Development in the US study who completed affect (Mroczek & Kolarz, 1998) and health measures (chronic conditions, Charlson, Szatrowski, Peterson, & Gold, 1994; functional limitations, McHorney, Ware, Lu, & Sherbourne, 1994; self-reported health) measured three times over 20 years. We ran three (one per health metric) random-intercept cross-lagged panel models, where positive and negative affect were modelled simultaneously. RESULTS: Results indicated that positive and negative affect significantly predicted future heath (functional limitations/self-reported health) and that this relationship was reciprocal (i.e. health measures predicted future affect). However, there were no significant cross-lagged relations between affect and chronic conditions. CONCLUSION: Our results suggest that both positive and negative affect play an equal role in predicting future health for functional limitations and self-reported health as well as highlight the bi-directionality of this relationship. Additionally, the degree to which affect predicts future health may be moderated by the type of health outcome.

Lighten UP! A community-based group intervention to promote psychological well-being in older adults.

OBJECTIVES: Aging is often characterized by declines in physical and mental health and increased risk for depression and social isolation. A protective factor that has been found to effectively moderate these phenomena is psychological well-being. The aim of his study was to pilot test a novel group intervention (Lighten UP! program) for the promotion of psychological well-being in older adults living in the community. METHODS: Lighten UP! is an eight-week program consisting of 90-minute group session designed to teach participants to identify and savor positive experiences across multiple domains of eudaimonic well-being. It was delivered to a sample of 103 men and women aged 60 or over, that were assessed pre- and post-intervention with Ryff's Psychological Well-being Scale (PWB), Life Satisfaction scale, Geriatric Depression Scale, Symptom Questionnaire, and items measuring sleep complaints and social well-being. RESULTS: At the end of the eight weeks, participants reported significantly increased PWB, life satisfaction, and social well-being along with lower levels of depression and fewer physical symptoms and sleep complaints. These gains were particularly robust for individuals with lower pre-program levels of PWB. CONCLUSIONS: This pilot investigation suggests the feasibility of a short group program for enhancing well-being in older adults. Future controlled investigations with long-term follow-up assessment are needed to confirm the effectiveness and sustained benefits of the Lighten UP!

Self-Reported Sleep Problems Prospectively Increase Risk of Disability: Findings from the Survey of Midlife Development in the United States.

OBJECTIVES: To determine whether subjective poor sleep prospectively increases functional limitations and incident disability in a national sample of adults living in the United States. DESIGN: Prospective cohort. SETTING: Longitudinal Survey of Midlife Development in the United States (MIDUS). PARTICIPANTS: Young, middle-aged, and older men and women (aged 24-75) surveyed in 1995/96 (MIDUS 1) and followed up in 2004-06 (MIDUS 2). Complete data were available for 3,620 respondents. MEASUREMENTS: Data were from telephone interviews and self-administered questionnaires. Participant reported chronic sleep problems within the prior month; functional limitations were assessed using the Functional Status Questionnaire. Demographic (age, sex, race), socioeconomic (educational attainment), health (chronic conditions, depression), and health behavior (obesity, smoking) covariates were assessed to reduce potential confounding. RESULTS: Approximately 11% of the sample reported chronic sleep problems at both MIDUS waves. Average number of activity of daily living (ADL) and instrumental activity of daily living (IADL) limitations increased significantly between MIDUS 1 (ADL limitations: 0.06; IADL limitations: 0.95) and MIDUS 2 (ADL limitations: 0.15; IADL limitations: 1.6; P < .001). Adjusted regression models estimating change in ADL scores showed that chronic sleep problems at MIDUS 1 predicted significantly greater increases in ADL (incident rate ratio (IRR) = 1.55, P < .001) and IADL (IRR = 1.28, P < .001) limitations. In those with no functional limitations at baseline, logistic regression models showed that chronic sleep problems significantly increased the odds of incident ADL (odds ratio (OR) = 2.33, 95% confidence interval (CI) = 1.68-3.24, P < .001) and IADL (OR = 1.70, 95% CI = 1.21-2.42, P = .002) disability. CONCLUSION: Reports of chronic sleep problems predicted greater risk of onset of and increases in functional limitations 9 to 10 years later. Poor sleep may be a robust and independent risk factor for disability in adults of all ages.

Persistent Psychological Well-being Predicts Improved Self-Rated Health Over 9-10 Years: Longitudinal Evidence from MIDUS.

Psychological well-being has been linked with better health, but mostly with cross-sectional evidence. Using MIDUS, a national sample of U.S. adults (N = 4,963), longitudinal profiles of well-being were used to predict in cross-time change over a 9-10 years in self-reported health. Well-being was largely stable, although adults differed in whether they had persistently high versus persistently low or moderate levels of well-being. After adjusting for sociodemographic factors, those with persistently high well-being reported better health (subjective health, chronic conditions, symptoms, functional impairment) across time compared to those with persistently low well-being. Further, persistently high well-being was protective of improved health especially among the educationally disadvantaged. The findings underscore the importance of intervention and educational programs designed to promote well-being for greater segments of society.

Inflammation Partially Mediates the Association of Multimorbidity and Functional Limitations in a National Sample of Middle-Aged and Older Adults: The MIDUS Study.

OBJECTIVE: Older adults are increasingly likely to have two or more chronic medical conditions (multimorbidity) and are consequently at greater risk of disability. Here we examine the role of inflammation in mediating the relationship between multimorbidity and disability. METHOD: Data are from the Survey of Mid-Life in the United States (MIDUS), a national sample of middle-aged and older adults. Structural equation models were used to assess direct relationships between multimorbidity and activities of daily living as well as indirect associations with a latent variable for inflammation (indicated by circulating levels of interleukin-6, C-reactive protein, and fibrinogen) as a mediator. RESULTS: After adjustment for potential confounds, multimorbidity was positively associated with inflammation (p < .001) and functional limitations (p < .001), and inflammation partially mediated the link between multimorbidity and functional limitations (p < .01). DISCUSSION: Inflammation may be an important biological mechanism through which chronic medical conditions are linked to disability in later life.

Variability of sleep duration is related to subjective sleep quality and subjective well-being: an actigraphy study.

While there is a large body of evidence that poor subjective sleep quality is related to lower subjective well-being, studies on the relation of objective sleep measures and subjective well-being are fewer in number and less consistent in their findings. Using data of the Survey of Mid-Life in the United States (MIDUS), we investigated whether duration and quality of sleep, assessed by actigraphy, were related to subjective well-being and whether this relationship was mediated by subjective sleep quality. Three hundred and thirteen mainly white American individuals from the general population and 128 urban-dwelling African American individuals between 35 and 85 years of age were studied cross-sectionally. Sleep duration, variability of sleep duration, sleep onset latency, and time awake after sleep onset were assessed by actigraphy over a period of 7 days. Subjective sleep quality was assessed with the Pittsburgh Sleep Quality Index, positive psychological well-being and symptoms of psychological distress were assessed with the Satisfaction with Life Scale and the Mood and Anxiety Symptom Questionnaire. In both white and African Americans high day-to-day variability in sleep duration was related to lower levels of subjective well-being controlling age, gender, educational and marital status, and BMI. By contrast, sleep duration, sleep onset latency, and time awake after sleep onset were not related to subjective well-being controlling covariates and other sleep variables. Moreover, the relationship between variability in sleep duration and well-being was partially mediated by subjective sleep quality. The findings show that great day-to-day variability in sleep duration--more than average sleep duration--is related to poor subjective sleep quality and poor subjective well-being.

Stressful events, social support, and cognitive function in middle-aged adults with a family history of Alzheimer's disease.

OBJECTIVE: To examine the associations of stressful experiences and social support with cognitive function in a sample of middle-aged adults with a family history of Alzheimer's disease (AD). METHOD: Using data from the Wisconsin Registry for Alzheimer's Prevention (WRAP; N = 623), we evaluated relationships between stressful events experienced in the past year, as well as social support, and cognitive performance in four domains: speed and flexibility, immediate memory, verbal learning and memory, and working memory. We assessed interactions between psychosocial predictors, and with APOE ε4 status. RESULTS: Greater number of stressful events was associated with poorer performance on tests of speed and flexibility. Greater social support was associated with better performance in the same domain; this relationship was diminished by the presence of the ε4 allele. No associations were seen in the remaining three domains. DISCUSSION: Psychosocial factors may influence cognition in at-risk individuals; influence varies by cognitive domain and ε4 status.

Living well with medical comorbidities: a biopsychosocial perspective.

OBJECTIVES: We take a biopsychosocial perspective on age-related diseases by examining psychological correlates of having multiple chronic conditions and determining whether positive psychological functioning predicts advantageous profiles of biological risk factors. METHOD: Respondents to the national survey of Midlife in the United States who participated in clinical assessments of health and biological processes (n = 998) provided information on chronic medical conditions and multiple domains of psychological functioning. Serum concentrations of interleukin-6 (IL-6) and C-reactive protein (CRP) were determined from fasting blood samples. RESULTS: Life satisfaction declined with increasing comorbidity while negative affect increased. In contrast, positive affect, purpose in life, and positive relations with others were unrelated to comorbidity status. Significant interactions showed that although IL-6 and CRP increased with increasing number of chronic conditions, respondents with higher levels of purpose in life, positive relations with others, and (in the case of CRP) positive affect had lower levels of inflammation compared with those with lower well-being scores. DISCUSSION: The results suggest that many older adults with medical comorbidities maintain high levels of positive psychological functioning that are in turn linked to better profiles of biological disease risk.

Sleep quality, social well-being, gender, and inflammation: an integrative analysis in a national sample.

Social isolation and poor sleep quality are independent predictors of poor health outcomes and increased biological risk for disease. We previously found in a small sample of older women that the presence of social ties compensated for poor sleep in associations with the inflammatory protein interleukin 6 (IL-6). The current study extended those findings to a national sample of middle-aged and older men and women. Using both subjective and objective sleep assessments, we found that in men, but not in women, social engagement moderated the association of subjective sleep complaints with both IL-6 and the soluble adhesion molecule E-selectin. Social engagement also moderated the link between sleep efficiency-assessed by actigraphy-and IL-6 levels in men, but not in women. These results extend our previous work and bolster the suggestion that positive psychological functioning may compensate for other risk factors in predicting advantageous profiles of biological risk in aging adults.

The Survey of the Health of Wisconsin (SHOW), a novel infrastructure for population health research: rationale and methods.

BACKGROUND: Evidence-based public health requires the existence of reliable information systems for priority setting and evaluation of interventions. Existing data systems in the United States are either too crude (e.g., vital statistics), rely on administrative data (e.g., Medicare) or, because of their national scope (e.g., NHANES), lack the discriminatory power to assess specific needs and to evaluate community health activities at the state and local level. This manuscript describes the rationale and methods of the Survey of the Health of Wisconsin (SHOW), a novel infrastructure for population health research. METHODS/DESIGN: The program consists of a series of independent annual surveys gathering health-related data on representative samples of state residents and communities. Two-stage cluster sampling is used to select households and recruit approximately 800-1,000 adult participants (21-74 years old) each year. Recruitment and initial interviews are done at the household; additional interviews and physical exams are conducted at permanent or mobile examination centers. Individual survey data include physical, mental, and oral health history, health literacy, demographics, behavioral, lifestyle, occupational, and household characteristics as well as health care access and utilization. The physical exam includes blood pressure, anthropometry, bioimpedance, spirometry, urine collection and blood draws. Serum, plasma, and buffy coats (for DNA extraction) are stored in a biorepository for future studies. Every household is geocoded for linkage with existing contextual data including community level measures of the social and physical environment; local neighborhood characteristics are also recorded using an audit tool. Participants are re-contacted bi-annually by phone for health history updates. DISCUSSION: SHOW generates data to assess health disparities across state communities as well as trends on prevalence of health outcomes and determinants. SHOW also serves as a platform for ancillary epidemiologic studies and for studies to evaluate the effect of community-specific interventions. It addresses key gaps in our current data resources and increases capacity for etiologic, applied and translational population health research. It is hoped that this program will serve as a model to better support evidence-based public health, facilitate intervention evaluation research, and ultimately help improve health throughout the state and nation.

Socioeconomic and psychosocial predictors of interleukin-6 in the MIDUS national sample.

OBJECTIVE: To investigate whether psychosocial factors (i.e., depression, anxiety, and well-being) moderated educational gradients in interleukin-6 (IL-6) levels using data from the Survey of Midlife Development in the U.S. (MIDUS). The influences of educational attainment and psychosocial factors on IL-6 in middle aged and older adults were also examined. DESIGN: Telephone interviews and mail surveys were utilized to collect educational attainment and psychosocial information from respondents (N = 1028). Respondents also participated in an overnight clinic visit, during which health information and a fasting blood sample were obtained. MAIN OUTCOME MEASURES: Serum levels of IL-6. RESULTS: Greater educational attainment predicted lower levels of IL-6 independent of age and gender, although this effect was attenuated after taking health behaviors, body mass index, waist-to-hip ratio, and chronic illnesses into account. Psychological well-being interacted with education to predict IL-6, such that for those with less education, higher well-being was associated with lower levels of IL-6. CONCLUSION: The findings indicate a strong association between education and inflammation, which can be further moderated by psychosocial factors. The health benefits associated with psychological well-being were particularly evident for individuals with low educational attainment.

Income, education, and inflammation: differential associations in a national probability sample (The MIDUS study).

OBJECTIVE: To examine the associations between income and education and three markers of inflammation: interleukin-6 (IL-6), C-reactive protein (CRP), and fibrinogen. Socioeconomic status is inversely linked with health outcomes, but the biological processes by which social position "gets under the skin" to affect health are poorly understood. METHOD: Cross-sectional analyses involved participants (n = 704) from the second wave of the national population-based Survey of Midlife Development in the United States (MIDUS). Data on pretax household-adjusted income and educational attainment were collected by questionnaire and telephone interview, respectively. Detailed medical history interviews, inventories of medication, and fasting blood samples for assessment of inflammatory proteins were obtained during an overnight clinic stay. RESULTS: All three inflammatory proteins were inversely associated with both income and education in bivariate analyses. However, multivariate regression models, adjusting for potential confounds, showed that only low income predicted higher levels of inflammatory proteins. Moreover, inclusion of IL-6 in the regression models for CRP and fibrinogen eliminated the associations with income. CONCLUSION: These results suggest that income explains the association between education and peripheral inflammation. In short, the reason that higher education is linked to reduced peripheral inflammation is because it reduces the risk for low income status, which is what is directly associated with reduced peripheral inflammation. The findings also suggest that the links between income and both CRP and fibrinogen are mediated by IL-6. These observations help to sharpen our understanding of the relationship between social position and biological markers of illness in the United States.