Although previous research has provided compelling evidence for the harmful effects that perceived discrimination can have on certain health outcomes, there has also been a lack of clarity about the strength of support for these relationships. Furthermore, a theoretical framework to understand the mechanisms underlying these effects has been lacking in the literature. The goal of our analysis was to systematically examine the literature to determine the strength of the evidence for these effects and to test a model that identifies pathways by which perceived discrimination may affect health. We additionally tested for the influence of important covariates and examined various dimensions of types of discrimination. The main premise underlying this meta-analysis was that discriminatory experiences influence health through the stress responses they engender. Through repeated exposure to discrimination, these stress responses—both physiological and psychological—can lead to mental and physical illnesses. The perception of discrimination can also put people at higher risk for engaging in health behaviors that may serve an adaptive, stress-reducing function in the short term but may ultimately increase risk for disease (see also Jackson & Knight, 2006
Overall, the results of this analysis supported our model and suggest that increased levels of perceived discrimination are associated with more negative mental and physical health. These results are consistent with previous research showing that perceived discrimination is associated with a variety of negative physical and mental health consequences, including increased psychological distress and increased symptoms of depression (T. Brown et al., 2000
; D. R. Williams & Mohammed, 2009
), and can be conceptualized as a specific form of stress. It is important to note that we also found that the perception of discrimination is related to heightened physiological stress responses, more negative psychological stress responses, increased participation in unhealthy behaviors, and decreased participation in healthy behaviors, suggesting promising avenues for future mediation analyses of these variables. Analysis of covariates using traditional research synthesis found that these relationships remained even when important demographic variables were taken into account.
It is important to note that although a direct causal pathway between perceived discrimination and health could not be determined because of the nonexperimental nature of the included studies, the results of longitudinal studies suggest that our proposed pathway is the most likely direction of the effect. For example, Pavalko, Mossakowski, and Hamilton (2003)
found that perceptions of discrimination reported in an initial wave of data were related to mental health reported 7–9 years later, even when controlling for emotional health during the initial data wave. Further, T. Brown et al. (2000)
examined the association between perceived discrimination and mental health over time and did not find evidence of an association between psychological distress or depressive symptoms during early waves of data and reports of perceived discrimination 1 year later, suggesting that poor mental health does not predict discrimination perceptions.
Although not tested within this study, the relationships between sustained cardiovascular activity and negative cardiovascular health (see Treiber et al., 2003
, for review) and between sustained negative emotional state and mental illness (National Institutes of Health [NIH], 2002
) are well documented in the literature. Treiber et al. (2003)
found that in large epidemiological studies following individuals over long periods (20 years or more), the blood pressure responses of initially normotensive individuals to stress-inducing manipulations were predictive of subsequent incidence of essential hypertension. Several other studies found an association between cardiovascular reactivity and other subclinical diseases including carotid atherosclerosis and increased left ventricular mass. These results suggest that increases in cardiovascular reactivity may lead to high blood pressure and/or other, more serious cardiovascular disease.
Chronic experiences of stress can also affect the levels of cortisol secreted in the body (Miller, Chen, & Zhou, 2007
). Sustained elevated levels of cortisol in the body are thought to be damaging to tissues and may lead to the dysregulation of biological systems (S. Cohen, Kessler, & Underwood, 1995
). However, other research has found that it is decreased levels of cortisol that are associated with pathology (Heim, Ehlert, & Hellhammer, 2000
). In a meta-analysis on stress and the hypothalamic-pituitary-adrenocortical axis in humans, Miller, Chen, and Zhou (2007)
found that for individuals enduring chronic stressors, cortisol levels were higher than normal. For those who experienced an acute stressor, cortisol levels declined to below normal as time elapsed. Another meta-analysis on cortisol response to stress (Dickerson & Kemeny, 2004
) found that experiences of stress tended to increase cortisol levels, and these effects were especially pronounced when the stress was perceived as uncontrollable, as with perceived discrimination. These findings suggest that individuals may be at risk for developing certain diseases, such as depression, schizophrenia, heart disease, and metabolic syndrome, when cortisol levels are elevated (Björntorp & Rosmond, 1999
; Nemeroff, 1996
; G. D. Smith et al., 2005
; Walker & Diforio, 1997
). However, as time passes and cortisol levels drop below normal, individuals may be more susceptible to other conditions, such as rheumatoid arthritis, fibromyalgia, and allergic conditions (Heim et al., 2000
; Raison & Miller, 2003
Work by McEwen (1998
) on allostatic load suggests that sustained levels of the stress response hormones, glucocorticoid and catecholamines, adaptive in normal levels, may also accelerate disease processes. Allostatic load, or the cost of elevated hormone levels in the body, may lead to the atrophy or death of neurons (McEwen, 1999
; Uno, Ross, Else, Suleman, & Sapolsky, 1989
), and if neglected over a long period, allostatic load may lead to a variety of health problems including depression, obesity, and cardiovascular disease (Brindley & Rolland, 1989
; Schulkin, McEwen, & Gold, 1994
; Seeman et al., 1997
). This concept is supported by animal research, which supports the hypothesis that stress hormone reactivity in early life can have lifelong consequences.
Mental states caused by stress may also be a pathway by which the perception of discrimination may lead to negative health. For example, Kubzansky et al. (1997)
found that worry, which is an important component of anxiety, may have increased the risk of coronary heart disease in a sample of men. Combined, these findings highlight the viability of the link between stress responding to the onset of mental and physical illness: Increased and/or sustained mental and physical responses to stress can lead to negative mental and physical health outcomes.
Similarly, we did not specifically test for the relationship between health-related behaviors and health outcomes, but there is strong evidence for how certain behaviors can negatively impact health, particularly for smoking, excessive drinking, and overeating. Clear links between smoking and disease outcomes such as lung cancer and several other forms of cancer, cardiovascular disease, and strokes are well established (Centers for Disease Control [CDC], 2008
; National Center for Health Statistics, 2003
; U.S. Department of Health and Human Services, 2004
). Harmful effects of excessive alcohol use are also well known. Alcohol use has been cited as the third leading lifestyle-related cause of death for the nation, causing approximately 75,000 deaths in the United States annually (CDC, 2006). Alcohol abuse has been linked to both short-term and long-term illness. Excessive alcohol intake can cause impaired brain function, which results in poor judgment, reduced reaction time, and the loss of balance and motor skills. These impairments can lead to an increased risk of unintentional injuries such as motor-vehicle accidents, falls, drowning, burns, and firearm injuries (G. S. Smith, Branas, & Miller, 1999
) and the increased likelihood to engage in risky sexual behavior (Naimi, Lipscomb, Brewer, & Colley, 2003
; Wechsler, Davenport, Dowdall, Moeykens, & Castillo, 1994
). In addition, excessive alcohol use has been linked with long-term illnesses including liver diseases such as hepatitis and cirrhosis (Kochanek, Murphy, Anderson, & Scott, 2004
). Obesity has been identified as a risk factor for developing several serious medical problems including hypertension, dyslipidemia, Type 2 diabetes, coronary heart disease, stroke, gallbladder disease, osteoarthritis, sleep apnea, respiratory problems, and endometrial, breast, prostate, and colon cancers (NIH, 1998
Past research has also found that when attempting to attain goals, self-regulatory failure may be related to increased feelings of dejection and agitation as well as decreased feelings of cheerfulness and quiescence (Higgins, Shah, & Friedman, 1997
). Other researchers have theorized that depression may have originated as a response to loss or failure to make progress toward goals (Akiskal & McKinney, 1973
; Strauman, 2002
). Accumulation of these sorts of failures is thought to lead to more prolonged and severe psychological consequences until the individual can no longer function in a normal fashion (Strauman, 2002
). Thus, for individuals who regard healthy living as a goal within their lives, frequent self-regulatory lapses regarding health-related behavior may have a negative effect not only on their physical health but also on their mental health.
Combined, these data highlight the importance of healthy behavior in preventing the onset of disease. The finding that perceived discrimination is associated with individuals’ increased participation in unhealthy behaviors and decreased participation in healthy behaviors suggests that health behaviors are part of the pathway by which the experience of perceiving discrimination may be related to negative health outcomes.
Theoretical and Methodological Implications
Few studies to date have been able to draw causal conclusions about the relationship between perceived discrimination and physical or mental health because of the cross-sectional designs of most of the research in this area. The challenges and shortcomings of manipulating discriminatory experiences in an experimental design are many, but several studies have attempted experimental methods by using videotaped and audiotaped discriminatory scenarios, speech and writing tasks in which past discrimination events are recalled, or actual gender or racial discrimination delivered by a confederate of the study. Further refinement of these manipulations will help produce more insight into the causal nature of this relationship, but one suggestion is that careful manipulation checks and post hoc questioning of participants be performed by experimenters to fully understand how the manipulations are experienced. In one experimental study, Merritt, Bennett, Williams, Edwards, & Sollers (2006)
assigned participants to listen to a blatantly racist discriminatory encounter or the same situation without reference to race. The unusual finding that individuals in the nonracist condition were showing more increased cardiovascular response than those in the blatantly racist condition alerted the researchers to examine the nonracist condition more closely. They found that most of the individuals in the nonracist condition perceived at least some racial discrimination within the audiotaped scenario even though none was explicitly present, with some participants perceiving extremely high levels of racist discrimination. In addition to highlighting how perceptions of discrimination within ambiguous situations may influence physiological responding, this study indicates the importance of checking manipulations of discrimination to ensure that they function as intended.
Another important area of future inquiry is the synergistic effects of mental and physical health outcomes. Depression has been related to suppressed immune functioning (see Robles, Glaser, & Kiecolt-Glaser, 2005
), emotional distress has been related to elevations in cortisol and other neuroendocrines (Dickerson & Kemeny, 2004
), and symptoms of anxiety and depression predict future incidence of coronary heart disease (Kubzansky et al., 1997
). In addition, increases in discriminatory experiences over time are associated with subsequent deteriorations in physical and mental health (Schulz et al., 2006
). However, not all research has found this pattern. Caputo (2003)
, in an analysis of youth over time, found that although perceived discrimination was related to decrements in mental health over time, it was not related to decreased physical health.
The effect of discrimination measurement type could not be fully analyzed within this analysis, but our results suggest the importance of closely examining recent and chronic stress in relationship to discrimination stress. We found that the point estimate for recent discrimination’s relationship with mental health was nearly twice that of the same analysis with lifetime discrimination. Although no other measurement analyses were significant, recent and chronic discrimination estimates were consistently more negative than those for lifetime discrimination, implying that these types of discrimination stress may have the most deleterious effects on health outcomes. Models of stress and coping (e.g., Lazarus & Folkman, 1984
) suggest that forming a clear mental representation of a stressor facilitates coping and reduces stress. Subtle forms of discrimination may produce more stress because of their ambiguous nature. When an individual is subjected to subtle mistreatment, it may be unclear as to what underlies the behavior, and as a result, the individual may have difficulty deciding on a coping response (e.g., D. R. Williams et al., 2003
Influence of Covariates
Analysis of commonly included moderators of the perceived discrimination–health link revealed some relatively weak patterns, with most analyses reporting null results. However, for those results that were significant, social support was more likely to buffer the relationship between perceived discrimination and negative mental health, supporting the notion that individuals with strong social support networks may be able to offset the pernicious effects of discrimination through close connections with others, although this relationship was the opposite for physical health. However, several of these relationships were conditional, suggesting that the type of social support sought, the specific health outcome studied, or the amount of discrimination stress experienced by individuals may affect whether this relationship is found. An important area of future research will be to examine these conditional results more fully to determine more precisely the role of social support in the discrimination experience.
Similar analyses on coping suggest that not all coping behaviors are equally successful in decreasing the effect of perceived discrimination on negative health. Although most results showed null effects, for those results that were significant, active or problem-focused coping seemed to be the most effective type of coping, with all significant effects showing a buffering effect and no evidence of exacerbation of the effect of discrimination stress on health. Conversely, passive or emotion-focused coping seemed to be much less effective at dealing with discrimination stress, with the majority of significant effects examined showing an exacerbating effect. However, conditional results suggest that the most effective way of coping with discrimination stress may vary by ethnicity, culture, and gender. For example, the John Henryism hypothesis suggests that active coping may be deleterious for Black men but beneficial for Black women (S. A. James, 1994
). Passive coping, although generally found to be detrimental, was the most beneficial type of coping for Asians in another study, though less so for Asians who had been acculturated to American society for a longer period (Noh et al., 1999
; Noh & Kaspar, 2003
). These differences in ethnicity, culture, and gender should be examined more closely by future researchers as a way to understand how certain coping responses to discrimination can be more effective than others.
Analysis of the moderating effect of group identification on the discrimination–health relationship suggests weak effects, with most effects studied showing null results. For those that were significant, approximately 60% revealed that high group identification was more likely to alleviate the negative effect of perceived discrimination, whereas the remaining 40% showed the opposite effect. However, the conditional nature of these results suggests that the beneficial nature of being highly identified with one’s group may vary by coping style, level of discrimination stress, and complexity of that identity. For example, although group identity, when found to have a significant effect, is generally found to be beneficial, in one study, individuals with a strong group identity who coped in a passive fashion reported lower self-esteem when reports of discrimination were high (Noh et al., 1999
). This relationship was reversed when reports of discrimination were low. In addition, Sabik and Tylka (2006)
found that highly gender-identified women with more complex identities were more protected from the effect of discrimination on health than women with less complex gender identities. These variations of responses based on level of perceived discrimination, identity complexity, and the interaction between identification and coping style provide ample avenues for future research to investigate these differences more closely.
These analyses did not include several potentially influential covariates and moderator variables in many of the models. Although this is partially due to the limits of meta-analysis itself, current conventions of data reporting were also a limiting factor. However, these limitations can be circumvented in the future if some convention is established as to the inclusion of certain choice variables in an initial model. For example, meta-analysis might be able to separate perceived discrimination’s correlation with health from the effects of age, education, income, and race if the majority of researchers examined the effects of perceived discrimination on health within a multiple regression model that included only perceived discrimination, age, education, income, and race before testing their secondary models. Similarly, if researchers presented partial correlations using a specified set of control variables, meta-analysts might be better able to isolate the direct relationship between perceived discrimination and health. Although this is a lofty goal, without it only the zero-order relationship between perceived discrimination and health effects can be statistically observed within a meta-analysis. For researchers interested in estimating the effect of variables such as social support, coping, and ethnic identity on the perceived discrimination–health link, consistently providing a simple regression model or partial correlation table including these variables before testing a fuller model might allow for meta-analysts to partial out these effects in the future. Until researchers agree to report results within a framework that involves consistent reporting of certain important variables (such as within a partial correlation table or a regression analysis step involving certain important covariates), the true magnitude of the perceived discrimination–health link will not be completely measurable through meta-analytic procedures.
Because variables that might have influenced the perceived discrimination–health relationship did not qualify for our analysis and thus were excluded, it is likely that the average weighted correlation produced by this analysis is a somewhat inflated estimate of the actual relationship between perceived discrimination and health. However, examination of our results in conjunction with those of multivariate models helps to strengthen the conclusions made here: The majority of associations within multivariate frameworks showed an association between increased levels of perceived discrimination and poorer health even with the inclusion of common covariates.
The same shortcoming may hold for the inability to include variables that might moderate the perceived discrimination–health link, such as social support, ethnic identity, and coping style. Despite their noninclusion, it is likely that these variables (and others such as mastery, neuroticism, hostility, and optimism) do have a considerable influence on this association between perceived discrimination and health. However, the nature of data presentation in the literature did not allow for the analysis of these relationships. To compensate for this limitation, we summarized studies that examined these three variables in relationship to perceived discrimination and health outcomes and identified patterns instead.
In addition, because of the relatively small number of studies using experimental or longitudinal designs, directional arrows for many of this study’s pathways could not be fully determined. However, studies that have used longitudinal and experimental designs (e.g., T. Brown et al., 2000
; Pavalko et al., 2003
) suggest that the pathways are in the directions suggested by our model.
Finally, it should also be noted that the conclusions we draw from our meta-analysis are based on a disproportionate number of studies that examine race-based discrimination. It may very well be the case that different types of discrimination are related to different outcomes, with some having more detrimental effects than others. As yet, the research in this area has not accounted for potential distinctions among types of discrimination within one research study that would enable a direct comparison of effects. The effects we found were in the same direction across all outcomes, however, regardless of type of discrimination (gender, sexual, unspecified discrimination, and unfair treatment were the others we examined) providing support for the potential generalizability of these findings beyond racial discrimination. Major et al. (2002)
provided some discussion of this issue in which they review research findings that members of stigmatized groups can exhibit both vulnerability and resilience in response to discrimination depending on a number of internal and contextual factors. As the literature in the field develops, a more comprehensive understanding of potential moderators of this effect is important to pursue. As Major et al. noted, group status may be important to consider, because the experience of discrimination is less likely to be stressful if the target has control over important resources or has the ability to avoid exposure to prejudiced individuals. However, we caution against attempts to make generalizations as to whether one type of discrimination may have more harmful effects than another type; changing contexts, power structures, intensity, duration, social support, and a host of other potential factors make such conclusions highly speculative.
Summary and Conclusions
Overall, the results of this analysis have supported previous researchers’ hypotheses that perceived discrimination may be related to both mental and physical health outcomes. In addition, our analysis provides evidence that this relationship may occur through the mechanisms of stress responses and health behaviors. These relationships remained even when important covariates were included in the analyses. Our synthesis of existing literature also suggests that social support, active coping styles, and group identification were most likely to serve a protective function in these pathways. Our findings refine the knowledge base in this area and guide a more mechanistic research agenda. We clarify some of these long-standing questions in the literature and suggest methodological strategies for how this research is conducted and interpreted in the future.