On the reliable assessment of cardiovascular recovery: an application of curve-fitting techniques.

The underuse of cardiovascular recovery as an adjunct to reactivity may stem from a lack of research on how to assess the process reliably. We explore the test-retest reliability of three simple, intuitive approaches to measuring recovery, and of a more sophisticated curve-fitting technique. Eighteen young normotensive subjects experienced three stressors twice each, with 10-min baseline, 3-min task, and 20-min recovery periods and continuous monitoring of heart rate and blood pressure. Reactivity showed moderate reliability, but the three simple approaches to measuring recovery revealed essentially none. However, the curve-fitting approach, using a three-parameter (amount, speed, and level of recovery) logistic function was reliable. This approach, capturing the inherently dynamic process of cardiovascular recovery, may allow researchers to usefully add the assessment of recovery to paradigms exploring reactivity as a risk factor for cardiovascular disease.

Social support and cardiovascular reactivity.

Recent experimental work on the benefits of social support in buffering cardiovascular stress responses builds on prior epidemiological, psychological, and physiological work. Epidemiological data show that social integration is associated with better health, but cannot unambiguously establish causality (it could be that healthy people attract more friends), nor that the mechanism is psychological (the mechanism could be behavioral; for example, with friends encouraging exercise). Social psychological work suggests that people prefer to be with others, especially in times of stress, and that they evaluate themselves, and their emotional responses, by observing the people around them. This work, while establishing a desire for affiliation, does not show that being with others translates into health benefits. Physiological evidence suggests that exaggerated cardiovascular responses to stress are associated with the development of hypertension and cardiovascular disease, but does not indicate how such potentially damaging stress responses can be reduced. Experimental work on social support and cardiovascular reactivity overcomes many of these limitations. The presence of an ally, especially a female, markedly reduces cardiovascular responses compared both to the presence of an non-supportive other, and to experiencing the stress alone. One fruitful area for further work is the role of social support following stress, both in speeding the cardiovascular return to pre-stress levels, and in limiting rumination-induced cardiovascular responses.

An historical context for behavioral models of hypertension.

OBJECTIVE: The purpose of this study is provide an historical context for current behavioral models of hypertension. METHODS: A selective sample of the cardiovascular reactivity literature was reviewed, from 1932 to present. RESULTS: In the earliest model, cardiovascular reactivity was regarded as a marker of disease risk; however, in later models, reactivity came to be viewed as a causal influence in the development of hypertension. As the models evolved, the underlying assumptions changed. Thus, the risk marker model assumed that cardiovascular responses to stress were a stable, generalized characteristic of the individual, and therefore the eliciting stimuli were arbitrary. The later models, however, assume that the nature of the eliciting stimulus is a determinant of the cardiovascular response. We describe the increasing complexity of the four models, and contrast their underlying assumptions and the implications of these assumptions. CONCLUSION: We provide an overview of study designs and variables that should be incorporated into studies seeking to understand the ways in which cardiovascular responses to stress may influence the development of hypertension.

Exposure to New York City as a risk factor for heart attack mortality.

OBJECTIVE: If New York City (NYC) residents' unusually high rate of ischemic heart disease (IHD) results from chronic exposure to that city, there might also be an effect of acute exposure among visitors to NYC. We explored this possibility and also whether IHD is reduced among NYC residents dying away from the city. METHODS: Using all US death certificates for 1985-1994, we examined (correcting for age, race, and sex) IHD deaths in three groups: NYC residents who died in the city, non-NYC residents visiting the city, and NYC residents traveling out of the city. RESULTS: IHD deaths among NYC residents dying in the city were 155% of the expected proportion (p < .0001). Among visitors to the city, such deaths were 134% of the expected proportion (p < .0001). The proportion of IHD deaths among NYC residents dying out of the city was only 80% of the expected value (p <.0001). These effects are not due to nearby commuters, recent immigrants, local classification practices, or socioeconomic status, and they do not appear in other US cities. CONCLUSIONS: With both chronic and acute effects of exposure to NYC, these data are consistent with the hypothesis that the stress of NYC is linked to the high rate of IHD.

What's in a name: mortality and the power of symbols.

One's attitude about oneself, and the treatment one receives from others, might be affected, in some small but measurable way, by stigmatic or salutary labeling due to one's name. If names affect attitudes and attitudes affect longevity, then individuals with "positive" initials (e.g., A.C.E., V.I.P.) might live longer than those with "negative" initials (e.g., P.I.G., D.I.E.). Using California death certificates, 1969-1995, we isolated 2287 male decedents with "negative" initials and 1200 with "positive" initials. Males with positive initials live 4.48 years longer (p<0.0001), whereas males with negative initials die 2.80 years younger (p<0.0001) than matched controls. The longevity effects are smaller for females, with an increase of 3.36 years for the positive group (p<0.0001) and no decrease for the negative. Positive initials are associated with shifts away from causes of death with obvious psychological components (such as suicides and accidents), whereas negative initials are associated with shifts toward these causes. However, nearly all disease categories display an increase in longevity for the positive group and a decrease for the negative group. These findings cannot be explained by the effects of death cohort artifacts, gender, race, year of death, socioeconomic status, or parental neglect.

An increase in the number of deaths in the United States in the first week of the month--an association with substance abuse and other causes of death.

BACKGROUND AND METHODS: There are regular changes in mortality rates, such as increased rates of death from influenza in the winter and from motor vehicle accidents on long holiday weekends. Previous research has shown that among persons with schizophrenia, the rates of cocaine use and hospital admissions increase at the beginning of the month, after the receipt of disability payments. Using computerized data from all death certificates in the United States between 1973 and 1988, we compared the number of deaths in the first week of the month with the number of deaths in the last week of the preceding month. RESULTS: The average number of deaths was about 5500 per day, or about 165,000 in a 30-day month. There were 100.9 deaths (95 percent confidence interval, 100.8 to 101.0) in the first week of the month for every 100 deaths in the last week of the preceding month. This was equivalent to about 4320 more deaths in the first week of each month than in the last week of the preceding month in an average year. Between 1983 and 1988, for deaths involving substance abuse and an external cause (such as suicides, accidents, and homicides), there were 114.2 deaths (95 percent confidence interval, 110.5 to 117.9) in the first week of the month for every 100 in the last week of the preceding month. There were significant increases in the number of deaths in the first week of the month for many causes of death, including substance abuse, natural causes, homicides, suicides, and motor vehicle accidents. CONCLUSIONS: In the United States, the number of deaths is higher in the first week of the month than in the last week of the preceding month. The increase at the beginning of the month is associated with substance abuse and other causes of death.

The influence of medical and legal authorities on deaths facilitated by physicians.

This study investigated whether two widely publicized cases of deaths facilitated by physicians were followed by significant peaks in mortality. In March, 1991, Timothy Quill, MD, published a controversial editorial describing the physician-assisted suicide (PAS) of his 45-year-old, female leukemia patient. In a landmark decision in December 1990, the Missouri Supreme Court allowed removal of life support for Nancy Cruzan, a comatose accident victim. Correcting for trends and seasonal fluctuations, the authors examined: (1) U.S. leukemia mortality in the period centered on Quill's editorial, and (2) mortality from accident/coma combinations in the period centered on the Missouri Supreme Court's decision on Cruzan. Female leukemia deaths rose 11.3% above the expected rate (p < .01) just after Quill's article was published. The more closely the decedent matched Quill's patient, the greater the peak, with the largest peak (33.9%) evident for female leukemia patients in their 40s, who were long-term residents of smaller communities (p < .05). Five possible explanations for the findings were assessed, leading to the conclusion that Quill's editorial elicited an increase in mortality. The involvement of physicians in this increase is supported by analysis of the Cruzan case. This showed a mortality peak of 57% for accident/coma patients following the court decision.

Gender, social support, and cardiovascular responses to stress.

OBJECTIVE: Laboratory research indicates that the presence of a supportive other can reduce physiological responses to a stressor. Whether there are gender differences, either on the part of the provider or the recipient, in this social support effect is explored. Such differences might shed some light on the frequent epidemiological reports of gender differences in social support and health. METHODS: Male and female subjects gave an impromptu speech and received either standardized supportive or nonsupportive feedback from a male or female confederate. Blood pressure and heart rate were monitored continuously during baseline and speech periods. RESULTS: Speakers with a supportive female audience showed a systolic increase of 25 mm Hg over baseline. Those with a nonsupportive female audience increased 36 mm Hg. A supportive male audience led to increases of 32 mm Hg, and a nonsupportive male audience 28 mm Hg. There was no significant effect of gender of subject. CONCLUSIONS: Results indicate that social support provided by women reduced cardiovascular changes for both male and female speakers compared with presence of a nonsupportive female audience. Social support from men did not. These findings suggest a possible mechanism that might help explain the epidemiological literature on the relationship between gender, social support, and health. The findings are consistent with the notion that married men are healthier because they marry women. Women do not profit as much from marriage or suffer as much from separation, in terms of health outcomes, because the support they gain or lose is the less effective support of a man. These findings render more plausible the possibility that differences in social support might contribute to health differences, through the dampening of cardiovascular responses to stress.

Can a machine tickle?

It has been observed at least since the time of Aristotle that people cannot tickle themselves, but the reason remains elusive. Two sorts of explanations have been suggested. The interpersonal explanation suggests that tickling is fundamentally interpersonal and thus requires another person as the source of the touch. The reflex explanation suggests that tickle simply requires an element of unpredictability or uncontrollability and is more like a reflex or some other stereotyped motor pattern. To test these explanations, we manipulated the perceived source of tickling. Thirty-five subjects were tickled twice--once by the experimenter, and once, they believed, by an automated machine. The reflex view predicts that our "tickle machine" should be as effective as a person in producing laughter, whereas the interpersonal view predicts significantly attenuated responses. Supporting the reflex view, subjects smiled, laughed, and wiggled just as often in response to the machine as to the experimenter. Self-reports of ticklishness were also virtually identical in the two conditions. Ticklish laughter evidently does not require that the stimulation be attributed to another person, as interpersonal accounts imply.

The generalizability of cardiovascular responses across settings.

The generalizability of cardiovascular reactivity change scores remains largely unsupported. In previous studies, several factors differed between laboratory and field, making poor lab-to-life correlations difficult to interpret. The present study varied only one parameter between the lab and field: setting. In this study, 24 females were studied on four occasions: twice in the lab (to provide test-retest reliability); once in a classroom; and once at home. After a baseline, subjects performed a math task, while blood pressure and heart rate were monitored. Procedures were identical in all sessions. Blood pressure changes were fairly reliable between the two lab sessions, with rs values 0.68 (systolic) and 0.62 (diastolic pressure); however, lab/nonlab correlations were lower (0.47 for SBP; 0.38 for DBP). This suggests that even a minor variation in procedure, such as a change in setting, can affect generalizability; other lab-field differences may have an even greater impact.

The social construction of cardiovascular reactivity.

One can view the "reactivity hypothesis" as having two basic forms: the individual difference or personality approach, which suggests that people who show exaggerated cardiovascular responses to stress are at increased risk of developing cardiovascular disease, and the situational or social psychological approach, which suggests that circumstances which give rise to unusually large responses are those that put people at risk of disease. Both versions rely on the generality of cardiovascular responses across situations. Evidence is presented from two studies which indicate that such generality may, however, be hard to come by. In the first study, examining the personality approach, we show that a simple change in setting dramatically attenuates the consistency of reactivity. In the second study, from the social psychological perspective, we show that subtle alterations in the situation have profound effects on group mean responses. In both cases, reactivity proved extremely sensitive to the context, suggesting that testing in arbitrary and artificial settings cannot be expected to generalize well to the real world. Instead, we argue, careful attention to psychological naturalism is essential, with the testing carefully matched to specific real-world phenomena of interest.

Implications of alternative methods of computing blood pressure means.

BACKGROUND: Blood pressure measures are traditionally averaged to compute a level across a period. There are, however, two ways of calculating such means: by assigning equal weights to each time interval or to each heartbeat. The former method is used commonly with intermittent measures, the latter with continuous measurements, though either can be calculated with either monitoring technique. For periods during which there is substantial variability in the cardiovascular levels, and in which the pulse is correlated with the blood pressure, the two techniques will produce different results. METHODS: We illustrated the difference between the two techniques by calculating mean blood pressure levels during two episodes, with the heart rate and blood pressure monitored continuously using the Finapres 2300 blood pressure monitor. RESULTS: During the first episode, there was dramatic variability in heart rate and blood pressure. The pulse-based calculations, which give greater weight to the periods during which the pulse is elevated, gave means for the systolic and diastolic blood pressures substantially higher than those obtained using time-based methods. During the second episode, both the heart rate and the blood pressure were stable, and we observed no difference between the results from the two methods of calculating the means. CONCLUSIONS: Because there are theoretical justifications for both methods of computation, and they can produce different results, it is important that researchers attend to the difference, and describe the technique used when presenting results.

Memory for pain and the delayed effects of distraction.

In spite of the popular belief that distraction is effective in coping with pain, there is evidence that a neutral distractor does not reduce people's reports of pain. However, it may be that distraction's effect is not detectable in immediate ratings, when the need to rate the pain forces the sufferer to concentrate on it. Instead, after a delay, when the pain itself is gone and the person must base the judgment on a memory of the event, having been distracted may attenuate the recalled pain. An experiment with 72 undergraduate participants tested this proposition, with 1 group highly distracted during cold-pressor pain and 1 group slightly distracted. Half of each group rated the pain immediately, and half waited 10 min after the event to rate the pain. The participants who gave immediate ratings showed no effect of distraction, but for participants who waited 10 min before giving their ratings, high distraction led to reduced reports of pain.

Social support effects on cardiovascular reactivity: is a stranger as effective as a friend?

OBJECTIVE: We investigated whether the effects on cardiovascular reactivity of social support from an audience member depend only on the behavior of that person or also depend on the relationship between the audience and the actor. That is, is there any added reduction in physiological response if the person who is nodding and smiling supportively is also a friend? METHOD: Ninety subjects gave a speech to an observer. In two of the conditions, this observer was a confederate of the experimenter and a stranger to the subject. This confederate acted in either a supportive or neutral manner during the speech. In the final condition, this observer was a friend, brought by the subject, who was then trained to show support in the same manner as the supportive confederate. The comparison of the two confederate conditions tested the effect of support, holding the relationship constant. The comparison of friend and confederate supportive conditions tested the effect of the relationship, holding the supportive behaviors constant. All participants were female. RESULTS: Both supportive conditions produced significantly smaller cardiovascular increases than the confederate-neutral condition, and the friend-supportive condition produced significantly smaller systolic blood pressure increases than the confederate-supportive (friend-supportive: 7.9 mm Hg: confederate-supportive: 14.9 mm Hg; confederate-neutral: 22.9 mm Hg). Differences for diastolic pressure and heart rate were not significant, although the data followed the same pattern. CONCLUSIONS: Social support from a friend attenuated cardiovascular reactivity in a laboratory setting to a greater degree than support from a stranger. The subjects' construal of the supportive behaviors can have an effect on reactivity, over and above the effects of the actual behaviors themselves.

Physiological stress reactivity and recovery: conceptual siblings separated at birth?

This article discusses theoretical assumptions underlying physiological stress reactivity research. It examines early conceptualizations of activation and recovery and contrasts these with current practices in designing, analyzing, and reporting stress reactivity studies. Study protocols from four major journals covering the last 2 years of publication were examined for current practices. Of the 105 studies which tested physiological reactivity, 63% collected recovery data but only 23% reported the recovery data. We concluded that stress recovery issues are neglected and a renewed case is made for their conceptual and ecological importance. The case for studying recovery is further supported by a selective review of studies using recovery protocols that revealed positive findings not apparent in reactivity comparisons only. Finally, options for sound design of recovery protocols, statistical processing of resulting data, and interpretation of findings are presented.

Effects of a metronome on the filled pauses of fluent speakers.

Filled pauses (the "ums" and "uhs" that litter spontaneous speech) seem to be a product of the speaker paying deliberate attention to the normally automatic act of talking. This is the same sort of explanation that has been offered for stuttering. In this paper we explore whether a manipulation that has long been known to decrease stuttering, synchronizing speech to the beats of a metronome, will then also decrease filled pauses. Two experiments indicate that a metronome has a dramatic effect on the production of filled pauses. This effect is not due to any simplification or slowing of the speech and supports the view that a metronome causes speakers to attend more to how they are talking and less to what they are saying. It also lends support to the connection between stutters and filled pauses.

The application of generalizability theory to blood pressure resting levels and mental stress responses.

BACKGROUND: Blood pressure measurements taken in the clinic or laboratory are assumed to generalize to the world outside. This is true both of casual blood pressure measurements and of changes in blood pressure responses to stress. Such generalizability is crucial to the usefulness of blood pressure measurements as predictors of long-term disease. In previous generalizability studies, several factors differed between clinic/laboratory and field, making it difficult to interpret the poor laboratory-life associations. The present study varied only one parameter between the laboratory and the field setting. SUBJECTS AND METHODS: Twenty-four women were studied on four occasions: twice in the laboratory, once in a classroom, and once at home. After a resting baseline, the subjects performed a mathematics task, while blood pressure and heart rate were monitored. Only the setting was varied across sessions. RESULTS: Test-retest correlations were 0.81 for systolic blood pressure levels (SBP) and 0.61 for diastolic blood pressure levels (DBP). Generalizability (G) coefficients for blood pressure levels were approximately the same as the reliabilities ( 0.82, SBP; 0.59, DBP), indicating that the change in location did not affect resting levels. However, for change scores, the reliabilities were higher than the G coefficients. Test-retest correlations were moderate: 0.68 (SBP) and 0.62 (DBP). G coefficients were 0.47 (SBP) and 0.36 (DBP), indicating that the generalizability of change scores suffered due to the change in test location. CONCLUSION: A minor variation in procedure, such as a change in setting, has little effect on the generalizability of blood pressure resting levels, but a substantial effect on stress-response changes. Other laboratory-field differences may have an even greater impact on generalizability.

Anxiety, alcohol, aphasia, and ums.

Although several studies have documented a link between anxiety and filled pauses (ums, ers, and uhs), numerous failures make it impossible to believe that the two are linked in any simple way. This article suggests anxiety may increase ums not when it makes the speech task harder but when it causes the speaker to pay attention to the speech. Two experiments examined this idea. One manipulated evaluation apprehension, and the other manipulated self-consciousness. Both showed dramatic increases in ums. Two more studies examined the real-world implications of this approach. Alcohol, which makes speaking harder but also makes speakers care less about what they say, was found to reduce ums. The second study found that Broca's aphasics, who produce simple speech but must deliberate over every word, produce many ums. Wernicke's aphasics may not talk well, but do not mind, and manage with few ums.