Fasting Serum Glucose and Cholesterol as Predictors of Cardiovascular Reactivity to Acute Stress in a Sample of African American College Students.

OBJECTIVE: African Americans are at a greater risk of cardiovascular hyperactivity to stress than Caucasians; however the risk factors for this activity are not clearly delineated for African Americans. The purpose of this study was to determine the ability of fasting serum cholesterol concentration and fasting serum glucose (FSG) to predict cardiovascular reactivity to stress in African Americans. DESIGN, SETTING, PARTICIPANTS: Serum cholesterol concentration and FSG levels were measured in 48 (40 women, 8 men) African American college students aged 18-30 years. Heart rate, cardiac output, stroke volume, mean arterial pressure and systolic and diastolic blood pressure were measured as the participants viewed a racially noxious scene on a digital video disc. Measurements were taken prior to the scene (pre stressor period), during the scene (stressor period), and while the participant recovered from the scene (recovery period). RESULTS: A multiple regression analysis revealed that total serum cholesterol and LDL significantly predicted diastolic blood pressure during the pre-stressor period. FSG significantly predicted mean arterial pressure during the recovery period, and predicted stroke volume during the pre-stressor period, stressor period, and the recovery period. CONCLUSIONS: FSG was a better predictor of cardiovascular reactivity to stress than serum cholesterol concentration, predicting mean arterial pressure and stroke volume. This finding may be due to the association of glucose with diabetes, which is more prevalent in African Americans.

Body mass index and waist circumference predictors of cardiovascular risk in African Americans.

OBJECTIVE: The purpose of our study was to determine which measure of obesity is better at predicting cardiovascular risk in African Americans. We hypothesized that BMI alone would be significantly associated with cardiovascular reactivity. We also hypothesized that waist circumference alone would be significantly associated with cardiovascular reactivity. Lastly, we hypothesized that BMI and waist circumference together would be more associated with cardiovascular reactivity and account for more of the variance than the two measures alone. DESIGN: BMI and waist circumference were measured in 105 African American college students (21 men and 84 women) aged 18-27. In addition, heart rate, cardiac output, stroke volume, and systolic and diastolic blood pressure were measured as the participants viewed a racially noxious scene on videotape. RESULTS: BMI and waist circumference analyzed separately were significantly associated with stroke volume, cardiac output, and systolic blood pressure. These positive associations showed that heavier participants had higher systolic blood pressure and their hearts pumped out greater blood volume compared to their thinner counterparts. Body mass index also completely mediated the relationship between waist circumference and cardiovascular activity. CONCLUSIONS: The findings may be attributed to the premise that the waist circumference standards are different for African Americans than for Whites. Future research should establish waist circumference thresholds that are better predictors of cardiovascular disease in African Americans.

Differences in heart rate among recent marijuana use groups.

BACKGROUND: Marijuana use increases cardiac sympathetic activity within minutes of its use and this effect may begin to decrease as soon as one hour after marijuana use. However, the cardiovascular effects of marijuana use more than an hour after use is poorly characterized. The purpose of the current study is to compare heart rate, a marker of cardiac sympathetic activity, across recent marijuana use groups (never used: N.=63; recent use [in the past 24 hours; subacute] N.=13; in the past 7 days, but not in the past 24 hours: N.=17). Overall, the current sample included 93 African American/Black college students, with a mean age of 20.03±2.21 years. METHODS: Participants completed a demographic form, a brief battery of psychological questionnaires, and had their heart rate assessed at baseline. RESULTS: Analysis of covariance showed that heart rate was statistically significantly lower in the recent use group (62.38 bpm) compared with the non-users group (73.92 bpm). This difference persisted before and after statistically adjusting for demographic covariates. CONCLUSIONS: These results suggest that there may be a cardiovascular process that occurs when using marijuana that results in a compensatory, reduced heart rate.

Body mass and cardiovascular reactivity to racism in African American college students.

OBJECTIVE: The purpose of the present study was to examine the effects of body mass on cardiovascular reactivity to racism in African American college students. DESIGN AND METHODS: Cardiac output, stroke volume, heart rate and blood pressure were measured as participants viewed a racially noxious scene on videotape. Body mass was measured using body mass index calculated using height and weight. We hypothesized that obese individuals would have greater cardiovascular reactivity to the scene than overweight individuals or individuals with normal weight. We also hypothesized that obese women would have the greatest cardiovascular reactivity to the scenes compared to overweight and normal weight women, and obese, overweight, and normal weight men. Lastly, we hypothesized that women would have greater cardiovascular reactivity than their male counterparts. RESULTS: Multivariate analysis of variance revealed that obese participants had significantly greater stroke volume and cardiac output than participants of normal weight, indicating that obese participants were less emotionally aroused by the stressor. There was also a significant interaction between sex and body mass for heart rate reactivity between the stressor and recovery periods. Obese women had the largest drop in heart rate, while obese men had the smallest drop from the stressor period to the recovery period. CONCLUSIONS: The findings revealed that obese participants were less aroused by the stressors and recovered from them more quickly than overweight participants and participants of normal weight. The frequent experiences of weight prejudices by the obese group may have desensitized them to other prejudices such as the racial intolerance shown in the stressor.

Black racial identity as a mediator of cardiovascular reactivity to racism in African-American college students.

OBJECTIVES: The purpose of the present study was to examine the ability of Black racial identity to mediate cardiovascular reactivity to racism. The Multidimensional Model of Racial Identity (MMRI), which consists of four dimensions, salience, centrality, regard, and ideology was used to define Black racial identity. The subdimensions of ideology are oppressed minority, nationalist, humanist, and assimilationist racial identities. DESIGN AND METHODS: Heart rate, cardiac output, stroke volume, and blood pressure were measured in 72 African-American men as they viewed a videotaped scene depicting racial profiling and a neutral scene. We hypothesized that individuals with high levels of Black-oriented identities (centrality, public regard, private regard, oppressed minority, and nationalist) would be less stressed by the racial profiling scenes than those low in these identities. In addition, we predicted that individuals with high levels of non-Black-oriented identities (assimilationist, humanist) would be more stressed by the racial profiling scenes than those with low levels of these identities. RESULTS: Private regard, humanist, and assimilationist racial identities were significantly associated with increased cardiovascular reactivity to the scenes. Specifically, private regard significantly predicted cardiac output and stroke volume responses to the scenes. In addition, assimilationist and humanist racial identities were associated with greater blood output and faster heart rates in response to the scenes. CONCLUSIONS: Although private regard (Black oriented) and assimilationist and humanist (non- Black oriented) racial identities showed elevated cardiovascular reactivity to the scenes, the underlying mechanisms of these associations may differ.