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Psychosomatic Medicine 68:73-79 (2006)
© 2006 American Psychosomatic Society

ORIGINAL ARTICLES

Violence Exposure and Optimism Predict Task-Induced Changes in Blood Pressure and Pulse Rate in a Normotensive Sample of Inner-City Black Youth

Rodney Clark, PhD, Ramona A. Benkert, PhD, APRN, BC and John M. Flack, MD, MPH

From the Department of Psychology (R.C.), College of Nursing (R.A.B.), and the Department of Internal Medicine, School of Medicine (J.M.F.), Wayne State University, Detroit, MI.

Address correspondence and reprint requests to Rodney Clark, PhD, Wayne State University, Biobehavioral Research Laboratory, Program for the Advancement of Youth and Urban Health, 5057 Woodward Ave., Suite 7204, Detroit, MI 48202. E-mail: rclark{at}sun.science.wayne.edu


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 METHODS
 RESULTS
 DISCUSSION
 NOTES
 REFERENCES
 
Objective: This investigation examined the association of violence exposure (home and neighborhood) and optimism to task-induced changes in systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse rate (PR).

Methods: Drawn from a larger investigation, the convenience sample for this study consisted of 172 normotensive black youth (mean age = 11.5 years, standard deviation = 1.3). Violence exposure and optimism were self-reported by participants, and task-induced changes in SBP, DBP, and PR were measured with an automated monitor during two sequentially administered digit-forward and digit-backward tasks.

Results: Hierarchical regression analyses revealed that violence exposure was inversely related to task-induced changes in SBP (p = .010) and DBP (p = .005). Optimism was not an independent predictor of blood pressure or PR changes (p-s > .32). The final step of these hierarchical analyses indicated that the effects of violence exposure and optimism interacted to predict task-induced changes in SBP (p = .013) and PR (p = .003). Follow-up regression analyses indicated that violence exposure was inversely related to task-induced changes in SBP among participants high in optimism and was positively associated with PR reactivity in participants low in optimism.

Conclusions: The youth in this study have intact mechanisms for buffering blood pressure responses to violence exposure, especially those who are more optimistic about their future—a person factor whose moderating effects might wane with advancing age.

Key Words: violence • optimism • blood pressure • pulse rate • black youth

Abbreviations: HTN = primary hypertension; SBP = systolic blood pressure; DBP = diastolic blood pressure; PR = pulse rate; M = mean; SD = standard deviation; SE = standard error; mm Hg = millimeters of mercury; kg/m = kilograms/meter.


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
METHODS
 RESULTS
 DISCUSSION
 NOTES
 REFERENCES
 
Primaryhypertension (HTN) continues to disproportionately affect blacks compared with other ethnic groups in the United States (1,2). Because of the prognostic significance of blood pressure on renal dysfunction, cardiovascular disease, cerebrovascular disease, and diabetes, research has focused on physiological and psychosocial (to a lesser degree) risk factors of HTN (3,4). Amid some research evidence to the contrary (5,6), a small but growing literature indicates that blood pressure and pulse rate hyperreactivity (reactivity) are among the physiological factors that predict subsequent blood pressure and HTN status (7–11). For example, among black children, Murphy et al (12) found that systolic reactivity was positively related to subsequent systolic blood pressure over a 1-year period. In a multiethnic sample of youth, Matthews et al (13) also found that increases in baseline systolic blood pressure (SBP) and diastolic blood pressure (DBP) over a 3-year period were independently predicted by SBP and DBP reactivity. To the extent that reactivity differentiates groups at varying risk for such preclinical cardiovascular disease states as elevated blood pressure (14), research that explicates person-by-situation variations in reactivity has the potential of better informing the development of prevention and intervention strategies aimed at reducing the prevalence of HTN in blacks.

As a potential source of chronic psychosocial stress, violence exposure is one situational reality that 1) is prevalent among inner-city youth (15,16), and 2) might aid with the identification of youth who are at increased risk of developing less "adaptive" cardiovascular profiles (15,17). Relative to the literature exploring behavioral and academic correlates of violence exposure in youth, far fewer investigations have explored the association of violence exposure to cardiovascular functioning (15). Among the studies that have examined the relationship of blood pressure and pulse rate (baseline and reactivity) to violence exposure, the findings have supported two competing interpretations. For example, in support of a hyperarousal interpretation of chronic stress exposure, which posits that repeated stress-induced sympathetic nervous system activation leads to such physiological changes as hyperreactivity and eventually higher baseline blood pressure levels (18), Wilson et al found that community exposure to violence was positively related to nighttime blood pressure (19) and to mean blood pressure-nondipping status in black male but not female adolescents (20). Saltzman et al (21) also found that exposure to marital violence was positively associated with pulse rate and salivary cortisol levels but was not related to reactivity or blood pressure.

Alternatively, consistent with a hypoarousal interpretation of the association between chronic stress exposure, it is also probable that youth learn to deal with inordinately high exposures to violence through desensitization/depersonalization or by way of a "defeat" coping response (17), thereby leading to less marked stress responses to these exposures and to relatively lower baseline blood pressure and pulse rate levels (22,23). In support of the hypoarousal interpretation, for example, Krenichyn et al (24) found that community violence exposure was inversely related to baseline pulse rate and diastolic blood pressure in an inner-city sample of black and Latino youth. Similar to these findings, Cooley-Quille et al (25) also observed a negative relationship between community violence exposure and baseline pulse rate in a sample of inner-city adolescents. In yet another study, Geen (26) found that prior exposure to violence attenuated blood pressure reactivity to subsequently observed violence in a sample of male undergraduate students. Because of the relative lack of literature examining the physiological correlates of violence (15), it remains to be determined if the previously observed association of violence exposure to baseline blood pressure and pulse rate extends to relatively reduced or elevated blood pressure and pulse rate reactivity in black youth.

Clearly, not all youth who are exposed to violence have negative exposure-related cardiovascular outcomes. As such, it might be possible to identify factors that moderate the relationship of violence exposure to these outcomes. Research suggests that parental/familial and person (youth) factors are among the predictors of biobehavioral functioning in youth (27–31) and should be investigated as potential moderators of any violence exposure–youth outcome association (17,24). Although no study could be found delineating the moderating effects of person factors to violence exposure and blood pressure and pulse rate reactivity, at least one investigation found that parental reports of select parenting behaviors moderated the association between community violence exposure and baseline blood pressure (24). In addition to research exploring the moderating effects of other parental/familial characteristics, investigations examining the additive and buffering effects of person characteristics continue to be warranted (15,17).

Optimism–pessimism is one person characteristic that might help to further clarify the aforementioned hyperarousal and hypoarousal interpretations of the violence exposure–blood pressure/pulse rate relationship. For example, it is possible that the observed negative association between violence exposure and blood pressure/pulse rate reactivity is stronger among youth who are more optimistic about their future prospects compared with youth who are more pessimistic. Given their future prospects, these more optimistic youth might ruminate less about their immediate environmental situation and reappraise acts of violence as being less stressful (i.e., involving reduced harm or threat). It is also possible that more optimistic youth who are exposed to a lot of violence perceive themselves as having more to lose than their counterparts with fewer prospects and as a result perceive their environmental situation as involving more harm or threat. Although no study could be found that has explicated the moderating effects of optimism–pessimism on violence exposure and cardiovascular functioning, research indicates that pessimism is positively associated with baseline blood pressure (32) and reactivity (33).

The present investigation adds to a relatively limited literature exploring the cardiovascular correlates of violence exposure and optimism in at least three ways. First, as opposed to examining the predictive use of violence exposure in the home or the community, the contribution of both situational contexts is examined in this study. Second, to the extent that blood pressure and pulse rate reactivity are among the precursors of higher baseline blood pressure levels (7–11), an examination of these precursors has the potential of leading to a more informed understanding of the mechanisms that underlie the previously observed relationships among violence exposure, optimism, and baseline blood pressure (21,24,25). Third, no other study could be found that has examined the extent to which optimism mitigates the effect of violence on reactivity. The two research questions for this exploratory study are as follows: 1) is violence exposure related to reactivity; and 2) does optimism moderate the association between violence exposure and reactivity?


   METHODS
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
RESULTS
 DISCUSSION
 NOTES
 REFERENCES
 
Participants
The normotensive participants for this investigation (n = 172, mean age = 11.5 years/standard deviation [SD] = 1.3, 50% girls) were a subset of 225 youth who participated in a larger longitudinal study examining the correlates of behavioral and physiological functioning in black youth from a large midwestern city. The decision to limit the primary examination of the research questions to this normotensive subsample was based on a converging body of research suggesting that individuals with high baseline blood pressure have greater blood pressure and pulse rate reactivity to laboratory tasks than individuals with normal baseline blood pressure (34–36). Using published guidelines (37–39), which underscore the importance of using gender-, age-, and height-specific norms when determining blood pressure status (i.e., normotensive versus high) in children and adolescents, 172 youth from the larger study (78%) who had average systolic or diastolic blood pressure levels below the 95th percentile of blood pressure (high, based on the average of the last four out of five baseline measurements) were classified as normotensive. Per parent report, no students were taking prescription medications for hypertension.

Questionnaires and Laboratory Task
Demographic
Several demographic (e.g., annual household income), medical (e.g., child prescription medications use), and health behavior (e.g., caffeine and alcohol consumption by child) questions were answered by the primary caregiver as a part of the larger study.

Mood States and Subjective Stress
Visual analog scales were used to assess task-induced changes in mood (anxiety, anger, alertness, and relaxation) and subjective stress. Task-induced changes were measured by subtracting pretask levels from posttask levels.

Violence Exposure
The Screen for Adolescent Violence Exposure scale (40) was used to provide a measure of violence exposure. The scale authors developed parallel scales to assess violence exposure in the neighborhood and in the home (e.g., "grownups hit me" and "I have seen someone get beat up") that could be further subdivided into three subscales distinguishing between violence that is experienced, heard, and seen. Using a five-point Likert scale that ranged from "zero" (never) to "4" (almost always), the 37-item home and neighborhood scales had possible scores that ranged from zero to 148. The standardized alpha coefficients in the current study for the home ({alpha} = 0.91) and neighborhood ({alpha} = 0.93) scales were very high. Psychometric data for inner-city youth, including blacks, are acceptable (40).

Optimism
Optimism was assessed with the Perceived Life Chances Scale (41). Using a four-point Likert scale that ranged from "zero" (very high) to "3" (very low), this 10-item scale (e.g., "What are the chances that ... you will graduate from high school?") had possible scores that ranged from zero to 30. All values were reverse-scored such that a higher score was indicative of more optimism (i.e., increased perceptions of life chances). The standardized alpha coefficient in the current sample was moderate ({alpha} = 0.81). No published psychometric data for this scale could be found with black youth.

Laboratory Task
A 3-minute digit-forward and a 3-minute digit-backward task were administered sequentially to elicit physiological responses (42). Adapted from the Wechsler Intelligence Scale for Children, 3rd Edition (Psychological Corporation, San Antonio, TX), these tasks required participants to recall a list of numbers that were read by the same ethnicity–gender research assistant who sat next to the participant. Other than the research assistant, an audience was not present during the tasks.

Apparatus
Blood pressure (systolic and diastolic) and pulse rate were measured before and during the laboratory tasks with the HDI/PulseWave Model CR-2000 Research CardioVascular Profiling System (Hypertension Diagnostics, Inc., Eagan, MN). This apparatus uses an oscillometric method to derive blood pressure estimates and has been shown to reliably assess blood pressure (43). All measurements were taken by a research assistant of the same ethnicity and gender who was trained on the apparatus.

Procedure
A semistructured presentation describing the larger research project was given by research assistants in the classrooms of teachers who agreed to participate in the study. Students who then expressed an interest in the research project were given a take-home research packet (information sheet, parental consent form, and parental questionnaires) for their primary caretaker to complete. By written directions, the primary caregiver was instructed to contact laboratory personnel before signing the consent form if they had questions about the study. Students who returned complete research packets within 2 weeks were scheduled for a psychosocial assessment.

Each student provided informed assent before the psychosocial assessment. The psychosocial assessment was administered to a small group of students (7–15 youth) and was conducted in a designated room in the school. To minimize a possible bias associated with reading ability, all questionnaire instructions and items were read aloud by one of the research assistants. Students were then instructed to respond on designated answer sheets.

Participants were scheduled for an individual physiological assessment within 3 weeks (15 school days) of their psychosocial assessment. Participants were instructed to refrain from consuming products containing caffeine (e.g., chocolate and cola) 6 hours before the physiological assessment. On arriving to a room designated for this assessment, questions were answered by an ethnicity- and gender-matched research assistant. Participants were then fit with an appropriately sized blood pressure cuff (small, medium, or large), which was placed on the nondominant arm. To verify accurate placement of the blood pressure cuff, reliability checks were conducted, and manual adjustments were made as needed. After a 5-minute rest period, participants completed the visual analog scales. For the purpose of this study, five baseline measurements of blood pressure and pulse rate were then taken every other minute during the 10-minute baseline period. During the task periods, blood pressure and pulse rate were assessed every minute. A second set of posttask visual analog scales was administered after the physiological assessment. After the physiological assessment, participants were thanked and paid a monetary incentive. The research protocol for the larger study was approved by the University’s Human Investigation Committee.

Data Reduction and Analyses
Criterion Variables
During the 10-minute baseline period, blood pressure and pulse rate measurements were averaged to obtain baseline levels (total readings = five); and, blood pressure and pulse rate measurements taken during the two 3-minute task periods were averaged to obtain task levels (total readings = six). As opposed to absolute values, change scores ({Delta}) for blood pressure and pulse rate reactivity (task minus baseline) were calculated and were used as the criterion variables in the regression analyses.

Predictor and Control Variables
Because preliminary correlation analyses indicated that there were moderate to high statistical relationships among the subscales (experienced, heard, and seen) assessing violence in the home (r’s = 0.53–0.72, p’s = 0.000) and neighborhood (r’s = 0.48–0.76, p’s = 0.000), the scale score for violence exposure in the home and neighborhood was created as opposed to three subscale scores for each of the home and neighborhood scales. These analyses also showed that there was a moderate statistical relationship between the scale scores assessing violence in the home and neighborhood (r = 0.57, p = .000). As such, the raw scores for the two 37-item scales measuring violence in the home and neighborhood were summed to create a combined 74-item total violence exposure scale. The standardized alpha coefficient for this combined scale was 0.95. In an attempt to reduce the statistical relationship between the predictor variables and the interaction term (44), the scores for the violence exposure and optimism scales were centered. These centered values served as the primary predictor variables in the regression analyses. Multiplying these centered values created the interaction term.

Two methods were used to select control variables for the regression analyses. The first method involved the identification of "established" correlates of blood pressure and pulse rate reactivity (age, parental history of hypertension, body mass index, gender, prescription medication use, performance ability [sum of correct responses for both tasks divided by sum of attempted responses for both tasks], and baseline blood pressure and pulse rate) by prior research and clinical knowledge (3,4,45). The second method involved the identification of suspected correlates of blood pressure and pulse rate reactivity (caffeine/alcohol consumption, household composition, maternal and paternal education, diabetes status, asthma status, inhaled beta agonist use, and task-induced changes in relaxation, anger, anxiety, alertness, and subjective stressfulness) (18,46,47) by measuring the bivariate association of these variables to task-induced changes in SBP, DBP, and pulse rate (PR). With this method, control variables were identified using a more liberal criterion of statistical significance (p < .10). Correlation analyses indicated that paternal education and task-induced changes in subjective stress were positively and significantly associated with {Delta} DBP (p = .054) and {Delta} PR (p = .043), respectively. Given the results of these two selection methods, the regression models predicting {Delta} SBP had seven control variables, and the models predicting {Delta} DBP and {Delta} PR had eight control variables.

t test analyses indicated that the 172 participants who were included in the primary analyses had violence exposure (p = .38) and optimism (p = .47) scores that were statistically similar to the scores of the 50 participants who were excluded from the primary analyses. With respect to the control variables, participants who were included in the primary analyses consumed more caffeine per day (p = .02) and were older (p = .006), less heavy (p = .001), and less alert during the task (p = .03) compared with participants who were excluded from the primary analyses.

Analyses
The Statistical Analysis System 8.01 (SAS Institute, Inc., Cary, NC) was used for all statistical analyses. To examine the relationship of violence exposure and optimism to {Delta} SBP, {Delta} DBP, and {Delta} PR, three hierarchical regression models were used. In each model, the control variables were entered in step 1; the main effects of violence exposure and optimism were entered in step 2; and the violence exposure by optimism interaction term was entered in step 3. The criterion of statistical significance for these regression analyses was p < .05. Consistent with procedures described by Aiken and West (44), significant interaction effects were also explored in follow-up analyses that regressed violence exposure on reactivity for participants whose optimism score was high (i.e., 1 SD above the mean; n = 35) and separately for participants whose optimism score was low (i.e., 1 SD below the mean; n = 25). Because of missing data for the paternal education variable, the sample size for the regression analysis predicting {Delta} DBP was 168. With a sample size of 168 to 172, an alpha of 0.05 (two-sided), 10 to 11 predictor variables, and an estimated small–medium effect size (F2 = 0.085; based on the definitions for multiple regression [48]), the power was 0.82 to 0.84 for each effect in step 3 (e.g., violence exposure x optimism interaction term, df = 1).


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
 RESULTS
DISCUSSION
 NOTES
 REFERENCES
 
Descriptive and Bivariate Analyses
With a mean body mass index of 21.4 kg/m2 (SD = 5.6), average SBP (110.7 mm Hg, SD = 7.4), DBP (57.7 mm Hg, SD = 5.6), and PR (81.5 beats/min, SD = 11.1) values were within normal limits. The combined performance ability score for the two-digit span tasks was 0.76 (SD = 0.15, range = 0.37–1.00). Approximately 43% of parents were currently married, and 23% reported that at least one parent had a positive history of HTN. Seventeen percent of participants had diabetes, and 15% were taking prescription medication (e.g., albuterol, cromolyn sodium, fexofenadine, loratadine, methylphenidate, paroxetine HCL, and risperidone). Roughly 35% of females had their first menses, and none were taking oral contraceptives. Per self-reports of youth and parents, all participants were black or African American.

In the current sample, the mean violence exposure value was 42.2 (SD = 32.5), and the mean optimism value was 35.7 (SD = 4.4). A t test analysis indicated a negligible relationship between the two predictor variables, violence exposure and optimism (p = .834). Correlation and t test analyses exploring the relationship between the predictor and control variables revealed 1) violence exposure was inversely related to paternal education (p = .000) and task-induced changes in subjective stress (p = .05); 2) boys reported more violence exposure than girls (p = .007); and 3) youth who were taking prescription medication were less optimistic than youth who were not taking prescription medication (p = .019).

Primary Analyses
Systolic Blood Pressure
In step 1 of the hierarchical regression analysis predicting {Delta} SBP, the seven control variables (age, parental history of hypertension, body mass index, gender, prescription drug use, performance ability, and baseline SBP) accounted for 3.4% of adjusted variability. None of the control variables were independent predictors of {Delta} SBP. The inclusion of the main effects (violence exposure and optimism) in step 2 accounted for an additional 3.8% of adjusted variability in {Delta} SBP. Whereas violence exposure was inversely and significantly associated with {Delta} SBP (p = .010), optimism (p = .423) was not significantly related to {Delta} SBP. In step 3, the violence exposure x optimism variable accounted for 2.9% of additional, adjusted variability in {Delta} SBP. The results from this final model (F [10, 162] = 2.93, p = .002) are shown in Table 1. Follow-up regression analyses indicated that violence exposure was not significantly related to {Delta} SBP among participants low in optimism (B = 0.04, standard error [SE] = 0.05, p = .414) and was inversely and significantly associated with {Delta} SBP among participants high in optimism (B = –0.10, SE = 0.04, p = .034). Mean baseline and change score values for blood pressure and pulse rate as a function of violence exposure and optimism are shown in Table 2.


View this table:
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  		TABLE 1. Final Step of Hierarchical Regression Models Explicating Association of Violence Exposure and Optimism to Task-Induced Changes in Systolic Blood Pressure ({Delta} SBP), Diastolic Blood Pressure ({Delta} DBP), and Pulse Rate ({Delta} PR)

 

View this table:
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  		TABLE 2. Mean (± Standard Deviation) Baseline Values and Change Scores ({Delta}) for Systolic Blood Pressure (SBP), Diastolic Blood Pressure (DBP), and Pulse Rate (PR) as a Function of Violence Exposure and Optimism

 

Diastolic Blood Pressure
In step 1 of the hierarchical regression analysis predicting {Delta} DBP, the eight control variables (age, parental history of hypertension, body mass index, gender, prescription drug use, paternal education, performance ability, and baseline DBP) accounted for 5.2% of adjusted variability. Age (p = .05) and paternal education (p = .018) were the only independent predictors in this step. The inclusion of the main effects (violence exposure and optimism) in step 2 accounted for an additional 5.2% of adjusted variability in {Delta} DBP. Again, whereas violence exposure was inversely and significantly associated with {Delta} DBP (p = .005), optimism (p = .325) was not significantly related to {Delta} DBP. In step 3, the violence exposure x optimism variable did not account for additional, adjusted variability in {Delta} DBP. The results from this final model (F [11, 157] = 2.73, p = .003) are shown in Table 1.

Pulse Rate
In step 1 of the hierarchical regression analysis predicting {Delta} PR, the eight control variables (age, parental history of hypertension, body mass index, gender, prescription medications use, task-induced changes in subjective stressfulness, performance ability, and baseline PR) accounted for 14.3% of adjusted variability. Baseline pulse rate (p = .000) was the sole independent predictor of {Delta} PR. Failing to account for additional, adjusted variability in {Delta} PR, neither violence exposure (p = .575) nor optimism (p = .450) was significantly related to {Delta} PR in step 2 (entry of main effects). In step 3, the entry of the violence exposure x optimism variable accounted for 4.1% of additional, adjusted variability in {Delta} PR. The results from this final model (F [10, 162] = 3.78, p = .000) are also shown in Table 1. Follow-up regression analyses indicated that violence exposure was positively related to {Delta} PR among participants low in optimism (B = 0.12, SE = 0.04, p = .006) but was not significantly associated with {Delta} PR among participants high in optimism (B = –0.05, SE = 0.05, p = .316).

Post Hoc Analyses
In reanalyses of the hierarchical regression models that included the 50 participants who had high baseline blood pressure, the direction and significance of the findings were similar. Specifically, in the model predicting {Delta} SBP, the significant violence exposure main effect (B = –0.04, SE = 0.01, p = .018) was moderated by a marginally significant violence exposure x optimism effect (B = –0.05, SE = 0.03, p = .059). In the model predicting {Delta} DBP, the significant violence exposure main effect (B = –0.03, SE = 0.01, p = .007) persisted and was not moderated by the violence exposure x optimism effect (p = .897). Finally, in the model predicting {Delta} PR, the violence exposure x optimism effect was significant (B = –0.06, SE = 0.03, p = .029).


   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
 RESULTS
 DISCUSSION
NOTES
 REFERENCES
 
In a sample of normotensive black youth, this study explored the relationship of violence exposure and optimism to blood pressure and pulse rate reactivity. Primary and post hoc hierarchical regression analyses indicated that there was a clear main effect of violence exposure on blood pressure (systolic and diastolic) reactivity. Contrary to research that supports a hyperarousal interpretation of the association between perceived stress and blood pressure reactivity (49,50), the finding in this study that violence exposure was inversely related to blood pressure reactivity lends credence to a hypoarousal interpretation (17,22–26). Consistent with this interpretation, as an alpha-adrenoreceptor sympathetic nervous system (SNS) receptor response whose sensitivity should diminish with repeated stress-induced SNS activation, the observed association between violence exposure and blood pressure reactivity is what might have been expected under normal conditions. Importantly, hypoarousal refers to relatively lower task-induced changes in blood pressure and pulse rate—not blood pressure and pulse rate changes that are lower than baseline levels. Unlike perceived racism—a psychosocial stressor that research suggests is positively related to blood pressure and pulse rate reactivity in blacks (49,50)—it is probable that some black youth learn to negotiate chronic exposures to violence through a defeat coping response.

Animal studies indicate that the defeat coping response pattern is associated with heightened neuroendocrine responses and blunted cardiovascular responses (22)—associations that are moderated by the home environment (51). As such, future research with youth should not be relegated to examining the relationship between community violence exposure and cardiovascular functioning, but should also explore the effects of violence exposure in other environments that might be sources of support and stress for youth (e.g., home and school). Moreover, given investigations suggesting that violence exposure is positively related to depression and posttraumatic disorder symptoms in youth (52–54), future research should also examine the possibility of psychopathology and cardiovascular dysfunction as being comorbid consequences of violence exposure. Although an initial goal of the larger investigation included examining the predictive use of violence exposure in the home, school, and community, administrators at two of the three participating schools objected to the assessment of violence exposure in their school. As a result, violence exposure in the school was not examined. In addition to research examining the competing interpretations of hyperarousal and hypoarousal, future studies should include a more comprehensive exploration of cardiovascular responses (i.e., other than blood pressure and pulse rate).

Inconsistent with research indicating that optimism is associated with blood pressure and PR reactivity (32,33), optimism was not significantly related to reactivity in the current investigation. Arguably, the index of optimism in this study of youth (perceived life chances) might be conceptually dissimilar enough from measures used in other research with youth (55) and adults (32,33,56) to account for this inconsistency. Also, given the purported complexity of the direct and interactive processes that influence the relationship between chronic stress and cardiovascular functioning (18,57–60), the interaction effects observed in this study are noteworthy. The results revealed that optimism interacted with violence exposure to predict task-induced changes in systolic blood pressure and PR. These interaction effects persisted after statistically adjusting for several control variables and after including youth who had elevated blood pressure readings. A significant interaction effect was not observed for DBP. In addition to replicating the findings here, further research examining physiological processes that differentially contribute to systolic and diastolic blood pressure (e.g., cardiac output and peripheral resistance) might elucidate the specific adrenoreceptor SNS mechanism that is more or less sensitive to such person characteristics as optimism and might help to clarify the lack of interaction for DBP.

Post hoc probing of the significant interaction effects suggested that the inverse relationship between violence exposure and SBP and reactivity was relegated to black youth who were high in optimism, and the positive association between violence exposure and pulse rate reactivity was relegated to black youth who were low in optimism. It is probable that person characteristics (e.g., high optimism/low pessimism) that are associated with blunted psychologic and physiological stress responses have the potential of decelerating or halting the physiological changes that are posited to increase the risk of negative vascular outcomes through a process other than downregulation of the alpha adrenoreceptors. It is also probable that person characteristics (e.g., low optimism/high pessimism) that are related to exaggerated stress responses contribute to the acceleration of physiological changes (e.g., heightened cardiac output) that are posited to increase the risk of negative vascular outcomes. Future investigations examining person characteristics that are related to hyper- and hypoarousal are needed for at least two reasons. First, it might be possible to identify black youth in chronically stressful environments who are at higher and lower risk of developing HTN. Second, if blood pressure reactivity increases the risk of HTN (10–14), and if such person characteristics as optimism mitigate this relationship, the development of more efficacious strategies aimed at reducing the prevalence of HTN in blacks might be realized. This research should consider the potential mediating and moderating effects of multiple person characteristics on the association between chronic stress and blood pressure reactivity, especially among blacks who are exposed to environments that are markedly stressful or uncontrollable.

Several caveats should be considered when interpreting the findings. First, because of the cross-sectional study design, baseline interpretations could not be drawn. Second, given that the sample was limited to black youth from an inner city, the findings might have limited generalizability to samples with different participant characteristics. Third, it is possible that the failure to examine the mitigating effects of other variables (e.g., chronic stress burden, physical activity, and dietary potassium/sodium intake) led to an overly simplistic interpretation of the observed relationships. For example, in states of high oxidative stress, the ability to downregulate SNS responses to chronic violence exposure might reduce the overall ability to downregulate SNS responses to stress. Fourth, the amount of adjusted variability accounted for by violence exposure and optimism (4.1–6.7%) was relatively small, highlighting the need for additional research delineating the direct and interactive effects of other person characteristics to blood pressure and PR rte reactivity. These caveats notwithstanding, the findings suggest that the youth in this study have intact mechanisms for buffering blood pressure responses to violence exposure, especially those who are more optimistic about their future—a person factor whose moderating effects might wane with advancing age. This study underscores the importance of examining the manner by which variations in person by situation factors predict reactivity in black youth—examinations that might have longer-term health implications for this group.

The authors thank Lesley Goins, Charles Williams, Karen Freeman, Brian Pitts, Jr., and Abraham Hagos for their assistance with data collection and entry.


   NOTES
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
 RESULTS
 DISCUSSION
 NOTES
REFERENCES
 

Preparation of this study was supported by grant nos. 1 K01 MH01867 from the National Institute of Mental Health, S P50 ES012395 from the National Institute of Environmental Health Sciences, and a Collaborative Scholars award from the College of Nursing at Wayne State University.

DOI:10.1097/01.psy.0000195744.13608.11


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
 RESULTS
 DISCUSSION
 NOTES
 REFERENCES
 

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