Susan B. Spitzer

Validation of the insulin sensitivity index (ISI0,120): comparison with other measures ☆

The purpose of this study was to explore possible calculations using oral glucose tolerance test (OGTT) values in order to develop a simple measure of insulin sensitivity. We devised a formula for an insulin sensitivity index, ISI(0,120), that uses the fasting (0 min) and 120 min post-oral glucose (OGTT) insulin and glucose concentrations. It appears to be generalizable across a spectrum of glucose tolerance and obesity. Most importantly, our data show that ISI(0,120) correlates well, when applied prospectively in comparative studies, with the insulin sensitivity index obtained from the euglycemic hyperinsulinemic clamp (r = 0.63, P < 0.001). This correlation was demonstrably superior to other indices of insulin sensitivity such as the HOMA formula presented by Matthews, and performed comparably to the computerized HOMA index. Measurement of insulin sensitivity has traditionally been possible only in research settings because of the invasiveness and expense of the methods used. Clinical investigators have therefore sought more practical methods to obtain an index of insulin sensitivity. Such an index should approximate insulin sensitivity as measured by the euglycemic hyperinsulinemic clamp (M). We present ISI(0,120), a simple yet sensitive measure of insulin sensitivity which is adaptable for use in clinical settings as well as large epidemiologic studies.

Effects of anger on left ventricular ejection fraction in coronary artery disease

This study examined the comparative potency of several psychological stressors and exercise in eliciting myocardial ischemia as measured by left ventricular (LV) ejection fraction (EF) changes using radionuclide ventriculography. Twenty-seven subjects underwent both exercise (bicycle) and psychological stressors (mental arithmetic, recall of an incident that elicited anger, giving a short speech defending oneself against a charge of shoplifting) during which EF, blood pressure, heart rate and ST segment were measured. Eighteen subjects had 1-vessel coronary artery disease (CAD), defined by greater than 50% diameter stenosis in 1 artery as assessed by arteriography. Nine subjects served as healthy control subjects. Anger recall reduced EF more than exercise and the other psychological stressors (overall F [3.51] = 2.87, p = .05). Respective changes in EF for the CAD patients were -5% during anger recall, +2% during exercise, 0% during mental arithmetic and 0% during the speech stressor. More patients with CAD had significant reduction in EF (greater than or equal to 7%) during anger (7 of 18) than during exercise (4 of 18). The difference in EF change between patients with CAD and healthy control subjects was significant for both anger (t25 = 2.23, p = 0.04) and exercise (t25 = 2.63, p = 0.01) stressors. In this group of patients with CAD, anger appeared to be a particularly potent psychological stressor.

Randomized clinical trial of cognitive behavioral stress management on human immunodeficiency virus viral load in gay men treated with highly active antiretroviral therapy.

Objective: Human Immunodeficiency Virus (HIV)–positive individuals treated with highly active antiretroviral therapy (HAART) may experience psychological burdens and negative mood states, which could impair their ability to derive maximum benefits from their medical treatment. We tested whether a cognitive behavioral stress management (CBSM) intervention in combination with antiretroviral medication adherence training (MAT) from a clinical pharmacist influences HIV viral load more than MAT alone. Methods: HIV-positive men who have sex with men were randomized to either a 10-week CBSM + MAT intervention (n = 76) or a MAT-Only condition (n = 54). Data were collected at baseline immediately following the 10-week intervention period, at 9 months postrandomization, and at 15 months postrandomization. Results: We found no differences in HIV viral load among the 130 men randomized. However, in the 101 men with detectable viral load at baseline, those randomized to CBSM + MAT (n = 61) displayed reductions of 0.56 log10 units in HIV viral load over a 15-month period after controlling for medication adherence. Men in the MAT-Only condition (n = 40) showed no change. Decreases in depressed mood during the intervention period explained the effect of CBSM + MAT on HIV viral load reduction over the 15 months. Conclusions: A time-limited CBSM + MAT intervention that modulates depressed mood may enhance the effects of HAART on suppression of HIV viral load in HIV+ men with detectable plasma levels. AIDS = acquired immunodeficiency syndrome; ACTG = Adherence to Combination Therapy Guide; BDI = Beck Depression Inventory; CBSM = cognitive behavioral stress management; CET = coping effectiveness training; EDTA = ethylenediaminetetraacetic acid; HAART = highly active antiretroviral therapy; HIV = human immunodeficiency virus; MAT = medication adherence training; MEMS = medication event monitoring system; POMS = Profile of Mood States.

Associations of blood pressure with self-report measures of anger and hostility among Black and White men and women.

This study examined associations between blood pressure (BP) and dispositional variables pertaining to anger and hostility. Black and White 25- to 44-year old male and female normotensives and unmedicated mild to moderate hypertensives completed four reliable self-report scales--the Cook-Medley Hostility (Ho) Scale, the Trait Anger subscale of the State-Trait Anger Scale (STAS-T), and the Cognitive Anger and Somatic Anger subscales of the Cognitive-Somatic Anger Scale--plus the Framingham Anger Scale and the Harburg Anger Scale. They also engaged in three laboratory tasks--Type A Structured Interview (SI), a video game, and a cold pressor task--that elicit cardiovascular reactivity. Ambulatory BP readings at home and at work were also obtained from most subjects. Blacks had significantly higher Ho and lower STAS-T scores than did Whites. Women reported higher levels of somatic anger than did men. White women showed significant positive correlations between STAS-T and systolic BP (SBP) and diastolic BP (DBP) both at rest in the laboratory and during the SI. Black women revealed significant positive relationships between STAS-T and SBP and DBP at rest in the laboratory and at work as well as with DBP during the cold pressor test. For Black men, cognitive anger and DBP at rest were positively related. In contrast, White men revealed significant negative correlations between Ho scores and SBP at rest and during the video game; these men also showed significant negative relationships between somatic anger and SBP and DBP reactivity during the cold pressor test. Women, but not men, showed significant positive relationships between all four anger measures and ambulatory BP at work. Whereas main effects relating anger and cardiovascular measures were not apparent as a function of race, Blacks demonstrated significantly greater SBP and DBP reactivity than Whites during the cold pressor test, with the converse occurring during the SI. Men demonstrated significantly greater DBP reactivity than women during the video game. The present findings indicate that self-reports on anger/hostility measures and cardiovascular responses to behavioral tasks differ as a function of race but that relationships between anger and BP regulation need to take into account possible race-sex interactions and selection of anger/hostility measures.

Applying latent growth curve modeling to the investigation of individual differences in cardiovascular recovery from stress.

Objective This paper provides an introduction to latent growth curve (LGC) modeling, a modern method for analyzing data resulting from change processes such as cardiovascular recovery from stress. LGC models are superior to traditional approaches such as repeated measures analysis of variance and simple change scores. Methods The basic principles of LGC modeling are introduced and applied to data from 167 men and women whose systolic blood pressure was assessed before, during, and after the cold pressor and evaluated speech stressors and who had completed the Cook-Medley Hostility Inventory. Results The LGC models revealed that systolic blood pressure recovery follows a different nonlinear trajectory after speech relative to the cold pressor. The difference resulted not from the initial decline at the completion of the stressor, but from higher levels at the end of the stressor and slower rate of change in decline for the speech. Hostility predicted the trajectory for speech but not for cold pressor. This relationship did not differ as a function of gender, although men had larger systolic blood pressure responses than women to both stressors. Conclusions LGC modeling yields an understanding of the processes and predictors of change that is not attainable through traditional statistical methods. Although our application concerns cardiovascular recovery from stress, LGC modeling has many other potential applications in psychosomatic research.

The influence of social situations on ambulatory blood pressure

&NA; Ambulatory blood pressure (BP) levels were assessed and types of activities were recorded every 20 min for a 12‐hr period in 131 normotensive or mild‐moderate hypertensive subjects. Systolic (S)BP and diastolic (D)BP levels varied significantly as a function of the social situation (alone, with family, with friends, or with strangers). BP levels were lowest when subjects were with family and were highest when subjects were with strangers.

Differential patterns of dynamic cardiovascular regulation as a function of task

In cardiovascular reactivity studies, interpretations of the processes supporting the blood pressure response may become problematic when systolic blood pressure, diastolic blood pressure, and heart rate all increase in response to a behavioral challenge. Therefore, in addition to evaluating these cardiovascular responses, this study examined cardiac output, total peripheral resistance and systolic time intervals derived from impedance cardiogram, electrocardiogram and phonocardiogram recordings during a speech stressor, a mirror tracing task, and a foot cold pressor test. All of the behavioral stressors elicited increases in blood pressure and heart rate, with the largest changes occurring during the overt speech. Based on the examination of the response patterns of the underlying hemodynamic variables it would appear that, in both men and women, the blood pressure increase during the speech preparation period was supported by increased cardiac output; the speech itself resulted in a mixed pattern of increased cardiac output and total peripheral resistance; whereas, the mirror tracing and cold pressor tasks produced increased total peripheral resistance. Although men and women produced similar response patterns to the behavioral challenges, sex differences in the estimates of myocardial contractility were observed during rest. These results provide evidence that different behavioral stressors can produce a distinct yet integrated pattern of responses, whose differences may be revealed, when impedance cardiography is used, to derive sufficient response measures for assessing dynamic cardiovascular processes.

Piecewise latent growth curve modeling of systolic blood pressure reactivity and recovery from the cold pressor test

Latent growth curve methodology was used to model systolic blood pressure reactivity and recovery from the cold pressor test. A piecewise regression approach permitted the separate but simultaneous modeling of the two components (reactivity and recovery) of the stress process. Data came from a study of 99 participants classified on the basis of gender, ethnicity, and family history of hypertension. Their systolic blood pressure was assessed at rest, during the cold pressor test, and during a task recovery period. A measure of task appraisal and readings from ambulatory blood pressure monitoring during a workday were also examined. The article illustrates a step-by-step approach to modeling reactivity and recovery. Results indicated that both reactivity and recovery were associated with subsequent systolic blood pressure at work.

Cardiovascular and neurohumoral responses to behavioral challenge as a function of race and sex.

Cardiovascular and hormonal responses to a structured interview, an electronic video game, a cold pressor test, and exercise on a bicycle ergometer were assessed in eighty-three 25- to 44-year-old normotensive Black and White men and women. Blacks showed significantly greater diastolic blood pressure (DBP) responses than Whites during the cold pressor test, which were not accounted for by an increase in plasma catecholamines. Exercise produced reliably greater systolic blood pressure (SBP) increases in Black women than in Black men or White women. Men showed significantly greater SBP and DBP changes than women during the video game. These findings suggest that the pattern of physiological reactivity elicited by challenge is related to the race and sex of the subjects.

The stability of cardiovascular parameters under different behavioral challenges: one-year follow-up

The stability of myocardial, peripheral vascular and systolic time-interval measures was assessed over a one-year period in a sample of ten healthy normotensive men. Subjects participated in three laboratory sessions, the first two of which were two weeks apart, and the third approximately one year later. Measures were sampled during the preparation and delivery of a speech, a mirror star tracing task, and the forehead cold pressor test. The results of intraclass correlations computed between the mean of the first two sessions and the third showed that baseline and task levels were highly reproducible across all tasks and most parameters over the one year interval. Results also showed that the long term stability of delta is largely task-dependent.