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Cognitive distancing, cognitive restructuring, and cardiovascular recovery from stress
Biological Psychology 86 (2011) 143–148
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Cognitive distancing, cognitive restructuring, and cardiovascular recovery from stress Britta A. Larsen ∗ , Nicholas J.S. Christenfeld University of California, San Diego, 9500 Gilman Drive, La Jolla, San Diego, CA 92093-0109, United States
a r t i c l e
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Article history: Received 6 November 2009 Accepted 22 February 2010 Available online 1 March 2010 Keywords: Cognitive distancing Cognitive restructuring Cardiovascular reactivity Recovery
a b s t r a c t Research suggests that phasic changes in cardiovascular reactivity can increase the risk of heart disease, yet much of this research has focused on the magnitude rather than the duration of reactivity. In recent years, studies have confirmed that recovery time is also a significant predictor of future heart cardiovascular disorders. Here we review these studies, as well as the cognitions and behaviors that have been found to influence recovery. We suggest that a useful distinction is that some utilize cognitive distancing while others seem to be based on cognitive restructuring. These different approaches have implications for the immediacy and permanence of the recovery effects. Finally, we outline the questions that have yet to be answered about recovery and how it could influence long-term health. © 2010 Elsevier B.V. All rights reserved.
1. Overview
2. Reactivity vs. recovery
Recent research on stress and cardiovascular disease has corroborated the popular belief that stress contributes to heart disease. While the development of heart disease is partially influenced by long-term, tonic conditions such as hypertension, it appears that acute, phasic increases in cardiovascular reactivity (CVR), such as those experienced during stress, can also contribute to cardiovascular disorders. There is another factor that has been found to significantly influence the effects of these phasic increases on long-term health—namely, the time it takes to return to baseline cardiovascular levels. This factor has often taken a backseat in the literature to the magnitude of initial reactivity, yet it has become clear in recent years that recovery time is a significant influencing factor for cardiovascular health, with numerous studies demonstrating the importance of this phenomenon to long-term health. There is also growing evidence on the psychological factors that can influence recovery time, and the activities that can expedite or impede return to baseline following stressors. Such factors, it is proposed here, can often meaningfully be divided into those that reduce attention paid to the past stressor – what we will call cognitive distancing – or those that promote some resolution or change in the way the stressor is regarded – what we will call cognitive restructuring. We will consider the utility and implications of such a distinction.
Studies have suggested that the magnitude of reactivity can predict cardiovascular disease. In both human and animal models, individuals displaying the greatest CVR when exposed to stressors have been found to be those with greatest progression of heart disease such as atherosclerosis (Kamarck et al., 1997; Manuck et al., 1983). These studies also show that reactivity is a risk factor independent of baseline heart rate and blood pressure levels; that is, it is not simply the case that those with high reactivity are also those with initially high blood pressure. Rather, even in the face of relatively normal resting cardiovascular parameters, pronounced reactivity in response to threat can, apparently, damage the system. This has lead numerous researchers to focus on reactivity and the factors that can exacerbate or buffer it, including personality traits such as hostility (Smith and Brown, 1991), and social events such as evaluation (Smith et al., 1997) and support (Kamarck et al., 1990). While the work on reactivity is clearly important, McEwen (1997) has postulated that it may not necessarily be reactivity alone that decides how stress affects the heart, but rather the “total area under the curve” is critically important. That is, if blood pressure (BP) and heart rate (HR) levels were mapped across time, it would not only be the height of the reactivity above normal that played an important role, but the total area above normal levels. This theory emphasizes two potentially distinct dimensions: reactivity height, and the duration elevation. According to this theory, it is not merely the factors that affect reactivity that are deserving of attention, but also those that affect how long that reactivity lasts. In recent years, the role of this second dimension, namely the duration of elevated CVR, has received more attention as cardiovas-
∗ Corresponding author. Tel.: +1 801 706 0351. E-mail address: [email protected] (B.A. Larsen). 0301-0511/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.biopsycho.2010.02.011
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cular recovery is increasingly recognized as an important aspect of disease etiology. In fact, several studies have found that even recovery from acute tasks over the course of several minutes can predict cardiovascular health years later. Stewart and France (2001), for example, found that recovery following stress predicted hypertension 3 years later. Cheng et al. (2003) also showed that, among men with diabetes, those whose heart rate recovery was slowest after 5 min of exercise had double the risk cardiovascular-related morality over a 15-year follow-up than those who recovered fastest. This effect is robust enough that heart rate recovery is now used as a prognostic indicator for cardiovascular disease. One difficulty with isolating the predictive value of recovery is that those taking the longest time to return to baseline are likely to be those who showed the greatest reactivity. That is, how long it takes one to come down will be influenced by how far one has gone up. However, Stewart and France (2001) found the predictive role of recovery held even when controlling for initial reactivity values. That is, of those displaying equal reactivity, the ones experiencing slower recovery were at greater risk for hypertension. Others have also found that the two values independently predict future heart health (Trieber et al., 2001), emphasizing that the two measures are in fact distinct predictors – and lending credence to McEwen’s assertion that total area, rather than just reactivity height, should be taken into account. Another study suggested that recovery could play a role in the heritability of heart disease. Gerin and Pickering (1995) measured reactivity and recovery to a laboratory stressor in healthy college students, some of whom had two parents with heart disease. The researchers found no difference in reactivity between the groups, but found that those whose parents had heart disease were slower to recover to baseline. It is possible, then, that parents and children share not necessarily plaque buildup or stiff arteries, but a tendency to recover slowly, which in turn leads to the development of heart disease. Delayed recovery could be a result of poor physical fitness, and fitness levels, rather than recovery time, could determine future cardiovascular health. Addressing this possibility, Cole et al. (1999) assessed heart rate recovery after exercise in subjects who were then followed for 6 years. The study found that slow recovery was positively related to all-cause mortality over the course of the study. Importantly, they also found that this result held even when controlling for physical fitness level, weight, and blood pressure. This suggests that, even among those who would seem to have good cardiovascular health, delayed recovery could still threaten future heart health. While the previous studies are consistent with there being an inherent physiological predisposition toward delayed recovery – that is, it reflects something about the cardiovascular system – latter studies have found that recovery can also be controlled by psychological factors. Glynn et al. (2002), for example, have shown that more emotionally upsetting tasks result in delayed cardiovascular recovery regardless of the initial reactivity level. This and several other studies have also demonstrated that following a psychological stressor, rumination, or mentally dwelling on and reliving the experience, can extend cardiovascular reactivity and delay recovery (Gerin et al., 2006; Neumann et al., 2001). Brosschot et al. (2006) have labeled this mental extension of stressors “perseverative cognition,” and posit that this could play a large – and maybe necessary – role in the development of stress-related diseases, including heart disease. Psychological influences over recovery from stress, then, may play a large role in cardiovascular health, and prevention of perseverative cognition following stressors could be cardio-protective. It is not clear, however, exactly which activities and cognitions following a stressor would be most effective at creating rapid, complete, and lasting recovery. We suggest that there are two general categories of alternatives: those that focus on distancing the indi-
vidual from the event, and those that focus on restructuring the individual’s cognitions about the event. That is, following a distressing incident, one can choose to not think about it at all, or to think about it in a constructive way. In the following pages, we review the current research on the effects of both cognitive distancing and cognitive restructuring on cardiovascular recovery and health and the utility of such a distinction. Most of the studies reviewed here examine acute recovery from laboratory stressors rather than the long-term development of heart disease. However, given the implications of recovery time for future cardiovascular health, it is possible that the success of each technique in delaying or expediting recovery could have serious implications for health. 3. Cognitive distancing When attempting not to think about something distressing, the easiest alternative is likely to think about something else – that is, to be distracted. Several studies have examined the effects on blood pressure recovery of presenting participants with distractions following stressful laboratory tasks. In the short run at least, this appears to expedite recovery. Following a stressful task, those given a distraction, such as a form to fill out or an article to read, generally demonstrate faster recovery to baseline than those left without distractions (Glynn et al., 2002). As the distraction tasks are designed to be affectively neutral, it is unlikely that the recovery is due to the task itself. Rather, this suggests that these tasks expedite recovery because they prevent cognitive fixation on the stressor. Distractions may be especially helpful for those prone to rumination. Gerin et al. (2006) asked subjects to participate in a pair of anger-recall tasks. After one of these they were given distractions while after the other they were left to sit alone and think. Subjects also filled out the destructive anger-behavior-verbal rumination (DAB-VR) scale, which measures the degree to which subjects engage in angry ruminative thoughts. The authors found that distraction interacted with trait rumination to influence blood pressure recovery. The subjects with the poorest blood pressure recovery following anger recall were those scoring highest in angry trait rumination. However, when given distractions, these subjects recovered much faster than before, to the extent that they did not differ from those low in trait rumination. It could be, then, that external distractions are not as helpful for those whose minds are naturally prone to wander even after an upsetting experience, but that for those with a tendency to ruminate on distressing incidents distractions can be a key to recovering mentally and physically. The cognitive distancing approach does, however, beg the question of whether distraction is likely to be beneficial in the long run. The studies show that distraction may expedite return to baseline in the minutes following an acute stressor, but it is possible that distraction delays, rather than eliminates, perseverative cognitive and the resulting elevated blood pressure. Results from some of the previous studies suggest distraction may have beneficial effects that persist at least somewhat beyond its temporal boundaries. Those subjects provided with distractors immediately following the laboratory stressor reported fewer troubled, ruminating thoughts in the period following the distraction (Gerin et al., 2006). A recent study by Glynn et al. (2007), however, showed that subjects who were not allowed to ruminate on a stressful task directly after it occurred still showed significant increases in blood pressure when they thought about it a week later. Those who had been allowed to ruminate directly after the task, however, did not show a significant increase when they thought about it a second time the following week, suggesting that mentally processing the experience could actually confer long-term benefits. The benefits of cognitive distancing, then – or at least the prevention of cognitive fixation –
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seem at this point to be short-term, and it is possible that some resolution or restructuring could be efficacious. 4. Cognitive restructuring The type of cognitive restructuring that is available will depend to a great extent on the nature of the stressor that occurred. In the case of an interpersonal offense, one likely appropriate and productive restructuring would be forgiveness. Such a process can include reevaluating the motives of the offender and considering the offender’s circumstances. Research on forgiveness and health has generally indicated that forgiveness, or at least having a forgiving personality, is associated with better health (Berry and Worthington, 2001). It is possible that forgiveness benefits health partially by reducing the duration of angry rumination and, consequently, by reducing CVR. Forgiveness, long a puzzle for philosophers, has received relatively little attention in the scientific literature, although recently researchers have begun to look at its direct effects on CVR. Several studies looking at hypothetical offenses or anger recall in the lab have found that focusing on forgiveness can reduce blood pressure levels that were initially elevated by thinking of such offenses. Witvliet et al. (2001) asked subjects to remember a time they were offended, then instructed them to visualize either holding onto the anger or focusing on forgiveness. All participants showed elevated blood pressure while remembering the offense; however, these levels returned to baseline for those visualizing forgiveness, while those holding onto anger showed continued elevated reactivity. It should be noted, however, that this study used no control group, thus recovery could have been due to forgiving thoughts or simply to thinking about anything other than anger. This study then leaves several questions unanswered that could usefully be explored. It would be informative to compare those envisioning forgiveness and anger to a control group thinking of something completely unrelated in order to differentiate effects of forgiving thoughts (restructuring) and effects of distracting thoughts (distancing). It also seems worthwhile, especially considering the results from the Glynn et al. (2007) study discussed above, to ask subjects from all conditions to re-envision the incident at a later time. It seems likely that if subjects who pictured forgiveness engaged in some sort of cognitive restructuring that they would react differently to the incident upon further recollection. Should they have benefited only from cognitive distancing, however, it is possible they would react physiologically to further rumination in the same way as before. Another study found that while those high in trait forgiveness showed no difference in reactivity from those low in trait forgiveness during an anger-recall task, their diastolic levels returned to baseline significantly faster (Friedberg et al., 2007). Again, however, this does not clarify exactly what mechanism is driving this effect. It could be that this result is mediated by those high in trait forgiveness having a tendency not to ruminate on offenses. Alternatively, they could be people who are able to restructure their thinking about an offensive situation. Whatever the mechanism, it appears it does not buffer against offense or anger, but reduces its duration, which in turn is cardio-protective. Other types of cognitive restructuring have also been shown to be beneficial for health. Writing about stressors, for example, has been demonstrated to confer various long-term health benefits. In a series of studies, Pennebaker has assigned subjects to write for a short time on several consecutive days about either superficial topics or about the things that were most troubling and traumatic to them. Using this and similar paradigms, Pennebaker and others have shown that writing about emotionally traumatic incidents can reduce frequency of physician visits (Francis and Pennebaker, 1992), boost the immune system (Petrie et al., 1998), reduce selfreported physical symptoms and depression (Greenberg and Stone,
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1992), and improve chronic conditions such as asthma and arthritis (Smythe et al., 1999). The majority of these effects are long-term rather than acute effects, being measured months after the initial study. Relatively few studies have examined the acute effects of writing on physiology in the lab, though the studies that have done so generally indicate that writing about traumas actually increases physiological activity (Hughes et al., 1994; Pennebaker et al., 1987). Additionally, most subjects report feeling increased distress while writing about such experiences. These findings suggest that writing itself does not necessarily improve health, but rather the process of writing leads to later benefits after the initial discomfort. It has been suggested that these benefits may stem from a cognitive restructuring of one’s views of the trauma, and that writing about it aids one in fitting it into a constructive, meaningful narrative. This is supported by the finding that those who use words associated with cause and insight receive the greatest health benefits from writing (Pennebaker et al., 1997). The findings again suggest that it is activities that prevent long-term carryover rather than the response in the face of the threat that can improve health. The importance of recovery is emphasized by the fact that this activity actually increases reactivity while subjects were writing about past emotional traumas, yet still seems to confer marked benefits compared to those who did not engage in emotional writing. One recent study directly investigated the cognitive mechanisms involved in traumatic writing by assigning subjects particular goals when writing about past traumas, such as finding benefits in the experience or re-experiencing the sensations involved (Guastella and Dadds, 2006). They found that of all subjects, those best able to neutralize the physical and mental distress associated with the incident were those assigned to seek new ways to alter their thinking about the incident (“devaluation condition). The results from this study highlight the benefits of restructuring specifically, and show that it is not necessarily revisiting the experience that confers benefits but the ability to relive it in a new way. Cognitive restructuring is at the center of cognitive-behavioral therapy (CBT), which can be used to address depression and anxiety but lately has also been used to address physical diseases, including cardiovascular disease. The use of CBT in treating patients with comorbid heart disease and depression has shown mixed results. The enhancing recovery in coronary heart disease patients (ENRICHD) study focused on using CBT and cognitive restructuring to address psychiatric disorders in patients with CVD, and found that in the short run the intervention improved mood and also some cardiovascular symptoms (Berkman et al., 2003). However, the intervention did not appear to have lasting effects on mortality (Berkman et al., 2003). It could be that cognitive restructuring helps in the short-term, but is not sufficient to effect mortality in patients who have already have developed heart disease. 5. The dilemma of anger expression While research has indicated that hostility and anger are bad for the heart (Chida and Steptoe, 2009; Williams et al., 1980), there are no clear findings on just what should be done about it. That is, it remains unclear whether it is better for health to express or “vent” anger, or to keep it in. These expression styles have been labeled “anger-out” and “anger-in,” and have been the center of a good deal of research investigating anger and health. Relatively little is known, however, about how the anger expression will influence physiological recovery from anger. In some of the earliest studies on anger and CVR, Hokanson examined the effects of retaliation on physiological recovery. Participants in these studies typically engaged in a highly frustrating task with a rude experimenter, after which they were given
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some way to retaliate, either physically (by administering electric shocks) or verbally (rating the experimenter’s abilities). Generally these studies indicate that expressing anger verbally or physically after an arousing, frustrating task reduces cardiovascular reactivity (Hokanson and Burgess, 1962; Hokanson and Shetler, 1961). Moreover, actual retaliation against an aggressor reduced CVR more than imagined retaliation, and retaliating against the actual offender expedited recovery more than did administering shocks to someone else. There seems to be something unique, then, about performing real acts of retaliation against actual offenders that offers benefits beyond simply performing the action or thinking about retaliatory actions. This is consistent with the finding that anger-in emotional styles impair health, with, it seems, a particular impact on cardiovascular health (Dembroski et al., 1985). However, studies have also shown that a compulsive anger-out emotional style is associated with coronary heart disease (Siegman et al., 2000). Furthermore, increases in both anger-in and anger-out emotional styles are associated with increased risk for hypertension (Everson et al., 1998). Neither type of expression, then, has been found to be significantly better than the other; rather, fixating on one type of anger coping, regardless of the type, appears to be damaging. Other studies have shown that not all anger expressions are the same, and that the purpose of venting could determine its influence on health. The constructive anger-behavior-verbal scale (CAB-V) measures the degree to which individuals express anger simply to inform the other party that they are angry, or whether they express it for constructive purposes, such as seeking to understand the other party’s point of view or finding new ways to deal with the situation (Davidson et al., 2000). Those high in constructive anger expression were found to have lower resting blood pressure, even after controlling for risk factors for hypertension. Additionally, an intervention study with high hostile males with CHD found that those showing decreases in hostility over time showed increases in constructive anger expression, which in turn predicted lower resting blood pressure (Davidson et al., 1999). These findings suggest that a cognitive restructuring approach following anger may be the best way to recover, though laboratory studies are clearly needed to investigate this possibility. 6. Other factors in cardiovascular recovery While many activities found to influence cardiovascular recovery fall into the categories of cognitive distancing and cognitive restructuring, there are some that do not easily fit into either. It is not necessarily the case that there is a third mechanism, however; the way that these factors work remains somewhat mysterious. Exercise, for example, has been found to affect recovery. This is perhaps not surprising, as stress is primarily a physiological response meant to facilitate action. Following a mental arithmetic task with harassment in the lab, participants in one study were assigned to exercise while others sat still (Chafin et al., 2008). While reactivity was initially greater in those who exercised, they returned to baseline following exercise sooner than those who did nothing. It is possible that part of the value of exercise lies in its potential role as a distractor, yet an additional distraction-matched control group did not recover as quickly, suggesting there is something particular about the physical act of exercising. Given the physical nature of the stress response and the tasks it presumably evolved to address, it is possible that a stressful task does not feel fully mastered until there has been some physical response to the threat. The fact that those who exercised experienced greater reactivity (during the exercise portion) yet still returned to baseline fastest emphasizes the dramatic role physical activity can play in recovery. Whether this works by changing whether people feel they have responded to the stressor appropri-
ately, changing the extent to which they continue to think about it, or through some other process is not yet known. Music has also been found to affect recovery. While distraction could again be pointed to as a possible mechanism, not all types of music have proven effective. Participants in one study listened to jazz, pop, or classical music following a laboratory stressor (Chafin et al., 2004). Those who listened to classical music recovered significantly faster than those who did not listen to music, while those listening to the other styles showed no difference in recovery from controls. One could speculate that the classical piece would not likely be the most distracting of the three, for an undergraduate population, and thus it is likely that another mechanism is responsible for the expedited recovery. It is not clear, however, that music will restructure the way that people think about the prior, stressful task in any explicit manner. It is possible that music sets an affective tone that can influence the mood of the subject, which in turn influences physiological responses. That is, it could work through some indirect mechanism, with classical conditioning influencing mood, which could then affect the way people regard the prior task. The sorts of probes that would provide evidence about any such mechanism, however, have not been tried. 7. The importance of flexibility Many of the factors reviewed here found to enhance recovery seem tied together by a common theme; specifically, cognitive flexibility. As reactivity and recovery can be influenced by cognitive factors, it is not surprising that being able to alter physiology relies partially on being able to alter cognitions, such as they way one views an offender or a traumatic event. When analyzing writing styles in subjects from several past traumatic writing studies, Campbell and Pennebaker (2003) found that those with a flexible writing style that changed from day to day were those receiving the most health benefits. This was not the case for those writing about superficial topics, however, which emphasizes that flexibility in framing and processing stressors in particular is important for health. The role of general flexibility in health has recently received increased attention, and could be a significant predictor of psychological and physical well being (Rozanski and Kubzansky, 2005). The incidence of cardiovascular disease is especially high among those with psychiatric disorders such as depression and anxiety, which could partially be explained by the cognitive inflexibility that marks such disorders (Larsen and Christenfeld, 2009). Additionally, a flexible coping approach that shifts from one coping style to another has been found to be more beneficial for health than any one style in particular (Folkman and Lazarus, 1980). Both strategies discussed here – cognitive distancing and restructuring – rely on an ability to shift thought patterns away from destructive rumination, either by shifting one’s focus entirely or shifting one’s point of view. As discussed previously, it is unclear whether distancing does in fact confer any sort of long-term benefits. It is clear, however, that unchanging fixation on a stressor can have both short- and long-term ramifications. 8. Conclusions Given the importance of cardiovascular recovery in health outcomes, a more thorough understanding of the factors that can aid and impede it is paramount. It seems clear that being able to discontinue angry rumination is essential, yet it is not entirely clear what traits or situations give rise to this flexibility. One possibility is that recovery relies on a sense of completion. That is, it is possible that recovery is delayed until we engage in behaviors that confirm the event has been dealt with. The retaliatory actions offered
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to some of the subjects in the Hokanson studies could have acted as such markers. Exercise could also, as discussed earlier, suggest the completion of a threatening encounter, as the stress response primarily facilitates physical action. It is possible that the recovery process does not really begin until the threat has demonstrably been overcome. Research shows that we are more likely to remember tasks that have not been completed, a phenomenon known as the Zeigarnik effect (Zeigarnik, 1927). Lewin (1927) has suggested that this enhanced memory is mostly a product of the tension created by leaving a task incomplete. It is likely, then, that stressors in particular would continue to produce tension until fully addressed and completed. This may be why distractions produce some alleviation in the short-term, but that, without some sort of cognitive restructuring, they do not offer lasting resolution of stress. Clearly many of these questions cannot be answered without more targeted research. It is unclear whether the benefits of cognitive flexibility come solely from restructuring the way one thinks about a stressor, or if being able to shift the topic of one’s thinking – that is, distracting oneself – confers the same benefits. Also, while a forgiving personality has been linked to better health, it is not entirely clear how this occurs. To date, no studies have examined actual offense and forgiveness in the lab to assess their effects on cardiovascular parameters. Further investigation of activities such as exercise and music could further illuminate how these aid recovery, and speak to whether they primarily influence mood through endorphins or other physiological mechanisms or whether they also influence cognitions. Furthermore, it remains unclear exactly what processes are involved in forgiveness. It could be that to be effective, forgiveness requires that one shift attribution from malicious intent to a product of circumstance, and this cognitive restructuring enables recovery and aids in feelings of completion. It could also be that forgiveness instead requires the ability simply to move on, and no longer dwell on the offense, and this cognitive distancing facilitates recovery. Investigating these possibilities could shed light not only on what constitutes forgiveness, but also the factors that are most important in recovery. Generating physiological responses to external threats is clearly an adaptive response. Research on the role of recovery in disease etiology, however, emphasizes that the stress response is not the only important adaptation we make in response to a threat. Just as important as changing our physiology to cope with, or even survive, the threat is the ability to assess when a threat is no longer present, and be able to return to baseline functioning. Without this accompanying shift, the ability to interpret and respond to a threat can become more damaging than protective. The importance of recovery is further magnified by the fact that many modern threats are of a diffuse, vague, social nature, without a clear stopping point. This makes the processes and effects of cognitive distancing and restructuring especially important in long-term cardiovascular responses, and consequently the development of cardiovascular disease. References Berkman, L.F., Blumenthal, J., Burg, M., Carney, R.M., Catellier, D., Cowan, M.J., et al., 2003. Effects of treating depression and low perceived social support on clinical events after myocardial infarction: the enhancing in coronary heart disease patients (ENRICHD) randomized trial. Journal of the American Medical Association 289 (23), 3106–3116. Berry, J.W., Worthington Jr., E.L., 2001. Forgivingness, relationship quality, stress while imagining relationship events, and physical and mental health. Journal of Counseling Psychology 48 (4), 447–455. Brosschot, J.F, Gerin, W., Thayer, J.F., 2006. The perseverative cognition hypothesis: a review of worry, prolonged stress-related physiological activation, and health. Journal of Psychosomatic Research 60, 113–124. Campbell, R.S., Pennebaker, J.W., 2003. The secret life of pronouns: flexibility in writing style and physical health. Psychological Science 14 (1), 60–65. Chafin, S., Roy, M., Gerin, W., Christenfeld, N., 2004. Music can facilitate blood pressure recovery from stress. British Journal of Health Psychology 9 (3), 393–403.
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Biological Psychology journal homepage: www.elsevier.com/locate/biopsycho
Cognitive distancing, cognitive restructuring, and cardiovascular recovery from stress Britta A. Larsen ∗ , Nicholas J.S. Christenfeld University of California, San Diego, 9500 Gilman Drive, La Jolla, San Diego, CA 92093-0109, United States
a r t i c l e
i n f o
Article history: Received 6 November 2009 Accepted 22 February 2010 Available online 1 March 2010 Keywords: Cognitive distancing Cognitive restructuring Cardiovascular reactivity Recovery
a b s t r a c t Research suggests that phasic changes in cardiovascular reactivity can increase the risk of heart disease, yet much of this research has focused on the magnitude rather than the duration of reactivity. In recent years, studies have confirmed that recovery time is also a significant predictor of future heart cardiovascular disorders. Here we review these studies, as well as the cognitions and behaviors that have been found to influence recovery. We suggest that a useful distinction is that some utilize cognitive distancing while others seem to be based on cognitive restructuring. These different approaches have implications for the immediacy and permanence of the recovery effects. Finally, we outline the questions that have yet to be answered about recovery and how it could influence long-term health. © 2010 Elsevier B.V. All rights reserved.
1. Overview
2. Reactivity vs. recovery
Recent research on stress and cardiovascular disease has corroborated the popular belief that stress contributes to heart disease. While the development of heart disease is partially influenced by long-term, tonic conditions such as hypertension, it appears that acute, phasic increases in cardiovascular reactivity (CVR), such as those experienced during stress, can also contribute to cardiovascular disorders. There is another factor that has been found to significantly influence the effects of these phasic increases on long-term health—namely, the time it takes to return to baseline cardiovascular levels. This factor has often taken a backseat in the literature to the magnitude of initial reactivity, yet it has become clear in recent years that recovery time is a significant influencing factor for cardiovascular health, with numerous studies demonstrating the importance of this phenomenon to long-term health. There is also growing evidence on the psychological factors that can influence recovery time, and the activities that can expedite or impede return to baseline following stressors. Such factors, it is proposed here, can often meaningfully be divided into those that reduce attention paid to the past stressor – what we will call cognitive distancing – or those that promote some resolution or change in the way the stressor is regarded – what we will call cognitive restructuring. We will consider the utility and implications of such a distinction.
Studies have suggested that the magnitude of reactivity can predict cardiovascular disease. In both human and animal models, individuals displaying the greatest CVR when exposed to stressors have been found to be those with greatest progression of heart disease such as atherosclerosis (Kamarck et al., 1997; Manuck et al., 1983). These studies also show that reactivity is a risk factor independent of baseline heart rate and blood pressure levels; that is, it is not simply the case that those with high reactivity are also those with initially high blood pressure. Rather, even in the face of relatively normal resting cardiovascular parameters, pronounced reactivity in response to threat can, apparently, damage the system. This has lead numerous researchers to focus on reactivity and the factors that can exacerbate or buffer it, including personality traits such as hostility (Smith and Brown, 1991), and social events such as evaluation (Smith et al., 1997) and support (Kamarck et al., 1990). While the work on reactivity is clearly important, McEwen (1997) has postulated that it may not necessarily be reactivity alone that decides how stress affects the heart, but rather the “total area under the curve” is critically important. That is, if blood pressure (BP) and heart rate (HR) levels were mapped across time, it would not only be the height of the reactivity above normal that played an important role, but the total area above normal levels. This theory emphasizes two potentially distinct dimensions: reactivity height, and the duration elevation. According to this theory, it is not merely the factors that affect reactivity that are deserving of attention, but also those that affect how long that reactivity lasts. In recent years, the role of this second dimension, namely the duration of elevated CVR, has received more attention as cardiovas-
∗ Corresponding author. Tel.: +1 801 706 0351. E-mail address: [email protected] (B.A. Larsen). 0301-0511/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.biopsycho.2010.02.011
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cular recovery is increasingly recognized as an important aspect of disease etiology. In fact, several studies have found that even recovery from acute tasks over the course of several minutes can predict cardiovascular health years later. Stewart and France (2001), for example, found that recovery following stress predicted hypertension 3 years later. Cheng et al. (2003) also showed that, among men with diabetes, those whose heart rate recovery was slowest after 5 min of exercise had double the risk cardiovascular-related morality over a 15-year follow-up than those who recovered fastest. This effect is robust enough that heart rate recovery is now used as a prognostic indicator for cardiovascular disease. One difficulty with isolating the predictive value of recovery is that those taking the longest time to return to baseline are likely to be those who showed the greatest reactivity. That is, how long it takes one to come down will be influenced by how far one has gone up. However, Stewart and France (2001) found the predictive role of recovery held even when controlling for initial reactivity values. That is, of those displaying equal reactivity, the ones experiencing slower recovery were at greater risk for hypertension. Others have also found that the two values independently predict future heart health (Trieber et al., 2001), emphasizing that the two measures are in fact distinct predictors – and lending credence to McEwen’s assertion that total area, rather than just reactivity height, should be taken into account. Another study suggested that recovery could play a role in the heritability of heart disease. Gerin and Pickering (1995) measured reactivity and recovery to a laboratory stressor in healthy college students, some of whom had two parents with heart disease. The researchers found no difference in reactivity between the groups, but found that those whose parents had heart disease were slower to recover to baseline. It is possible, then, that parents and children share not necessarily plaque buildup or stiff arteries, but a tendency to recover slowly, which in turn leads to the development of heart disease. Delayed recovery could be a result of poor physical fitness, and fitness levels, rather than recovery time, could determine future cardiovascular health. Addressing this possibility, Cole et al. (1999) assessed heart rate recovery after exercise in subjects who were then followed for 6 years. The study found that slow recovery was positively related to all-cause mortality over the course of the study. Importantly, they also found that this result held even when controlling for physical fitness level, weight, and blood pressure. This suggests that, even among those who would seem to have good cardiovascular health, delayed recovery could still threaten future heart health. While the previous studies are consistent with there being an inherent physiological predisposition toward delayed recovery – that is, it reflects something about the cardiovascular system – latter studies have found that recovery can also be controlled by psychological factors. Glynn et al. (2002), for example, have shown that more emotionally upsetting tasks result in delayed cardiovascular recovery regardless of the initial reactivity level. This and several other studies have also demonstrated that following a psychological stressor, rumination, or mentally dwelling on and reliving the experience, can extend cardiovascular reactivity and delay recovery (Gerin et al., 2006; Neumann et al., 2001). Brosschot et al. (2006) have labeled this mental extension of stressors “perseverative cognition,” and posit that this could play a large – and maybe necessary – role in the development of stress-related diseases, including heart disease. Psychological influences over recovery from stress, then, may play a large role in cardiovascular health, and prevention of perseverative cognition following stressors could be cardio-protective. It is not clear, however, exactly which activities and cognitions following a stressor would be most effective at creating rapid, complete, and lasting recovery. We suggest that there are two general categories of alternatives: those that focus on distancing the indi-
vidual from the event, and those that focus on restructuring the individual’s cognitions about the event. That is, following a distressing incident, one can choose to not think about it at all, or to think about it in a constructive way. In the following pages, we review the current research on the effects of both cognitive distancing and cognitive restructuring on cardiovascular recovery and health and the utility of such a distinction. Most of the studies reviewed here examine acute recovery from laboratory stressors rather than the long-term development of heart disease. However, given the implications of recovery time for future cardiovascular health, it is possible that the success of each technique in delaying or expediting recovery could have serious implications for health. 3. Cognitive distancing When attempting not to think about something distressing, the easiest alternative is likely to think about something else – that is, to be distracted. Several studies have examined the effects on blood pressure recovery of presenting participants with distractions following stressful laboratory tasks. In the short run at least, this appears to expedite recovery. Following a stressful task, those given a distraction, such as a form to fill out or an article to read, generally demonstrate faster recovery to baseline than those left without distractions (Glynn et al., 2002). As the distraction tasks are designed to be affectively neutral, it is unlikely that the recovery is due to the task itself. Rather, this suggests that these tasks expedite recovery because they prevent cognitive fixation on the stressor. Distractions may be especially helpful for those prone to rumination. Gerin et al. (2006) asked subjects to participate in a pair of anger-recall tasks. After one of these they were given distractions while after the other they were left to sit alone and think. Subjects also filled out the destructive anger-behavior-verbal rumination (DAB-VR) scale, which measures the degree to which subjects engage in angry ruminative thoughts. The authors found that distraction interacted with trait rumination to influence blood pressure recovery. The subjects with the poorest blood pressure recovery following anger recall were those scoring highest in angry trait rumination. However, when given distractions, these subjects recovered much faster than before, to the extent that they did not differ from those low in trait rumination. It could be, then, that external distractions are not as helpful for those whose minds are naturally prone to wander even after an upsetting experience, but that for those with a tendency to ruminate on distressing incidents distractions can be a key to recovering mentally and physically. The cognitive distancing approach does, however, beg the question of whether distraction is likely to be beneficial in the long run. The studies show that distraction may expedite return to baseline in the minutes following an acute stressor, but it is possible that distraction delays, rather than eliminates, perseverative cognitive and the resulting elevated blood pressure. Results from some of the previous studies suggest distraction may have beneficial effects that persist at least somewhat beyond its temporal boundaries. Those subjects provided with distractors immediately following the laboratory stressor reported fewer troubled, ruminating thoughts in the period following the distraction (Gerin et al., 2006). A recent study by Glynn et al. (2007), however, showed that subjects who were not allowed to ruminate on a stressful task directly after it occurred still showed significant increases in blood pressure when they thought about it a week later. Those who had been allowed to ruminate directly after the task, however, did not show a significant increase when they thought about it a second time the following week, suggesting that mentally processing the experience could actually confer long-term benefits. The benefits of cognitive distancing, then – or at least the prevention of cognitive fixation –
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seem at this point to be short-term, and it is possible that some resolution or restructuring could be efficacious. 4. Cognitive restructuring The type of cognitive restructuring that is available will depend to a great extent on the nature of the stressor that occurred. In the case of an interpersonal offense, one likely appropriate and productive restructuring would be forgiveness. Such a process can include reevaluating the motives of the offender and considering the offender’s circumstances. Research on forgiveness and health has generally indicated that forgiveness, or at least having a forgiving personality, is associated with better health (Berry and Worthington, 2001). It is possible that forgiveness benefits health partially by reducing the duration of angry rumination and, consequently, by reducing CVR. Forgiveness, long a puzzle for philosophers, has received relatively little attention in the scientific literature, although recently researchers have begun to look at its direct effects on CVR. Several studies looking at hypothetical offenses or anger recall in the lab have found that focusing on forgiveness can reduce blood pressure levels that were initially elevated by thinking of such offenses. Witvliet et al. (2001) asked subjects to remember a time they were offended, then instructed them to visualize either holding onto the anger or focusing on forgiveness. All participants showed elevated blood pressure while remembering the offense; however, these levels returned to baseline for those visualizing forgiveness, while those holding onto anger showed continued elevated reactivity. It should be noted, however, that this study used no control group, thus recovery could have been due to forgiving thoughts or simply to thinking about anything other than anger. This study then leaves several questions unanswered that could usefully be explored. It would be informative to compare those envisioning forgiveness and anger to a control group thinking of something completely unrelated in order to differentiate effects of forgiving thoughts (restructuring) and effects of distracting thoughts (distancing). It also seems worthwhile, especially considering the results from the Glynn et al. (2007) study discussed above, to ask subjects from all conditions to re-envision the incident at a later time. It seems likely that if subjects who pictured forgiveness engaged in some sort of cognitive restructuring that they would react differently to the incident upon further recollection. Should they have benefited only from cognitive distancing, however, it is possible they would react physiologically to further rumination in the same way as before. Another study found that while those high in trait forgiveness showed no difference in reactivity from those low in trait forgiveness during an anger-recall task, their diastolic levels returned to baseline significantly faster (Friedberg et al., 2007). Again, however, this does not clarify exactly what mechanism is driving this effect. It could be that this result is mediated by those high in trait forgiveness having a tendency not to ruminate on offenses. Alternatively, they could be people who are able to restructure their thinking about an offensive situation. Whatever the mechanism, it appears it does not buffer against offense or anger, but reduces its duration, which in turn is cardio-protective. Other types of cognitive restructuring have also been shown to be beneficial for health. Writing about stressors, for example, has been demonstrated to confer various long-term health benefits. In a series of studies, Pennebaker has assigned subjects to write for a short time on several consecutive days about either superficial topics or about the things that were most troubling and traumatic to them. Using this and similar paradigms, Pennebaker and others have shown that writing about emotionally traumatic incidents can reduce frequency of physician visits (Francis and Pennebaker, 1992), boost the immune system (Petrie et al., 1998), reduce selfreported physical symptoms and depression (Greenberg and Stone,
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1992), and improve chronic conditions such as asthma and arthritis (Smythe et al., 1999). The majority of these effects are long-term rather than acute effects, being measured months after the initial study. Relatively few studies have examined the acute effects of writing on physiology in the lab, though the studies that have done so generally indicate that writing about traumas actually increases physiological activity (Hughes et al., 1994; Pennebaker et al., 1987). Additionally, most subjects report feeling increased distress while writing about such experiences. These findings suggest that writing itself does not necessarily improve health, but rather the process of writing leads to later benefits after the initial discomfort. It has been suggested that these benefits may stem from a cognitive restructuring of one’s views of the trauma, and that writing about it aids one in fitting it into a constructive, meaningful narrative. This is supported by the finding that those who use words associated with cause and insight receive the greatest health benefits from writing (Pennebaker et al., 1997). The findings again suggest that it is activities that prevent long-term carryover rather than the response in the face of the threat that can improve health. The importance of recovery is emphasized by the fact that this activity actually increases reactivity while subjects were writing about past emotional traumas, yet still seems to confer marked benefits compared to those who did not engage in emotional writing. One recent study directly investigated the cognitive mechanisms involved in traumatic writing by assigning subjects particular goals when writing about past traumas, such as finding benefits in the experience or re-experiencing the sensations involved (Guastella and Dadds, 2006). They found that of all subjects, those best able to neutralize the physical and mental distress associated with the incident were those assigned to seek new ways to alter their thinking about the incident (“devaluation condition). The results from this study highlight the benefits of restructuring specifically, and show that it is not necessarily revisiting the experience that confers benefits but the ability to relive it in a new way. Cognitive restructuring is at the center of cognitive-behavioral therapy (CBT), which can be used to address depression and anxiety but lately has also been used to address physical diseases, including cardiovascular disease. The use of CBT in treating patients with comorbid heart disease and depression has shown mixed results. The enhancing recovery in coronary heart disease patients (ENRICHD) study focused on using CBT and cognitive restructuring to address psychiatric disorders in patients with CVD, and found that in the short run the intervention improved mood and also some cardiovascular symptoms (Berkman et al., 2003). However, the intervention did not appear to have lasting effects on mortality (Berkman et al., 2003). It could be that cognitive restructuring helps in the short-term, but is not sufficient to effect mortality in patients who have already have developed heart disease. 5. The dilemma of anger expression While research has indicated that hostility and anger are bad for the heart (Chida and Steptoe, 2009; Williams et al., 1980), there are no clear findings on just what should be done about it. That is, it remains unclear whether it is better for health to express or “vent” anger, or to keep it in. These expression styles have been labeled “anger-out” and “anger-in,” and have been the center of a good deal of research investigating anger and health. Relatively little is known, however, about how the anger expression will influence physiological recovery from anger. In some of the earliest studies on anger and CVR, Hokanson examined the effects of retaliation on physiological recovery. Participants in these studies typically engaged in a highly frustrating task with a rude experimenter, after which they were given
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some way to retaliate, either physically (by administering electric shocks) or verbally (rating the experimenter’s abilities). Generally these studies indicate that expressing anger verbally or physically after an arousing, frustrating task reduces cardiovascular reactivity (Hokanson and Burgess, 1962; Hokanson and Shetler, 1961). Moreover, actual retaliation against an aggressor reduced CVR more than imagined retaliation, and retaliating against the actual offender expedited recovery more than did administering shocks to someone else. There seems to be something unique, then, about performing real acts of retaliation against actual offenders that offers benefits beyond simply performing the action or thinking about retaliatory actions. This is consistent with the finding that anger-in emotional styles impair health, with, it seems, a particular impact on cardiovascular health (Dembroski et al., 1985). However, studies have also shown that a compulsive anger-out emotional style is associated with coronary heart disease (Siegman et al., 2000). Furthermore, increases in both anger-in and anger-out emotional styles are associated with increased risk for hypertension (Everson et al., 1998). Neither type of expression, then, has been found to be significantly better than the other; rather, fixating on one type of anger coping, regardless of the type, appears to be damaging. Other studies have shown that not all anger expressions are the same, and that the purpose of venting could determine its influence on health. The constructive anger-behavior-verbal scale (CAB-V) measures the degree to which individuals express anger simply to inform the other party that they are angry, or whether they express it for constructive purposes, such as seeking to understand the other party’s point of view or finding new ways to deal with the situation (Davidson et al., 2000). Those high in constructive anger expression were found to have lower resting blood pressure, even after controlling for risk factors for hypertension. Additionally, an intervention study with high hostile males with CHD found that those showing decreases in hostility over time showed increases in constructive anger expression, which in turn predicted lower resting blood pressure (Davidson et al., 1999). These findings suggest that a cognitive restructuring approach following anger may be the best way to recover, though laboratory studies are clearly needed to investigate this possibility. 6. Other factors in cardiovascular recovery While many activities found to influence cardiovascular recovery fall into the categories of cognitive distancing and cognitive restructuring, there are some that do not easily fit into either. It is not necessarily the case that there is a third mechanism, however; the way that these factors work remains somewhat mysterious. Exercise, for example, has been found to affect recovery. This is perhaps not surprising, as stress is primarily a physiological response meant to facilitate action. Following a mental arithmetic task with harassment in the lab, participants in one study were assigned to exercise while others sat still (Chafin et al., 2008). While reactivity was initially greater in those who exercised, they returned to baseline following exercise sooner than those who did nothing. It is possible that part of the value of exercise lies in its potential role as a distractor, yet an additional distraction-matched control group did not recover as quickly, suggesting there is something particular about the physical act of exercising. Given the physical nature of the stress response and the tasks it presumably evolved to address, it is possible that a stressful task does not feel fully mastered until there has been some physical response to the threat. The fact that those who exercised experienced greater reactivity (during the exercise portion) yet still returned to baseline fastest emphasizes the dramatic role physical activity can play in recovery. Whether this works by changing whether people feel they have responded to the stressor appropri-
ately, changing the extent to which they continue to think about it, or through some other process is not yet known. Music has also been found to affect recovery. While distraction could again be pointed to as a possible mechanism, not all types of music have proven effective. Participants in one study listened to jazz, pop, or classical music following a laboratory stressor (Chafin et al., 2004). Those who listened to classical music recovered significantly faster than those who did not listen to music, while those listening to the other styles showed no difference in recovery from controls. One could speculate that the classical piece would not likely be the most distracting of the three, for an undergraduate population, and thus it is likely that another mechanism is responsible for the expedited recovery. It is not clear, however, that music will restructure the way that people think about the prior, stressful task in any explicit manner. It is possible that music sets an affective tone that can influence the mood of the subject, which in turn influences physiological responses. That is, it could work through some indirect mechanism, with classical conditioning influencing mood, which could then affect the way people regard the prior task. The sorts of probes that would provide evidence about any such mechanism, however, have not been tried. 7. The importance of flexibility Many of the factors reviewed here found to enhance recovery seem tied together by a common theme; specifically, cognitive flexibility. As reactivity and recovery can be influenced by cognitive factors, it is not surprising that being able to alter physiology relies partially on being able to alter cognitions, such as they way one views an offender or a traumatic event. When analyzing writing styles in subjects from several past traumatic writing studies, Campbell and Pennebaker (2003) found that those with a flexible writing style that changed from day to day were those receiving the most health benefits. This was not the case for those writing about superficial topics, however, which emphasizes that flexibility in framing and processing stressors in particular is important for health. The role of general flexibility in health has recently received increased attention, and could be a significant predictor of psychological and physical well being (Rozanski and Kubzansky, 2005). The incidence of cardiovascular disease is especially high among those with psychiatric disorders such as depression and anxiety, which could partially be explained by the cognitive inflexibility that marks such disorders (Larsen and Christenfeld, 2009). Additionally, a flexible coping approach that shifts from one coping style to another has been found to be more beneficial for health than any one style in particular (Folkman and Lazarus, 1980). Both strategies discussed here – cognitive distancing and restructuring – rely on an ability to shift thought patterns away from destructive rumination, either by shifting one’s focus entirely or shifting one’s point of view. As discussed previously, it is unclear whether distancing does in fact confer any sort of long-term benefits. It is clear, however, that unchanging fixation on a stressor can have both short- and long-term ramifications. 8. Conclusions Given the importance of cardiovascular recovery in health outcomes, a more thorough understanding of the factors that can aid and impede it is paramount. It seems clear that being able to discontinue angry rumination is essential, yet it is not entirely clear what traits or situations give rise to this flexibility. One possibility is that recovery relies on a sense of completion. That is, it is possible that recovery is delayed until we engage in behaviors that confirm the event has been dealt with. The retaliatory actions offered
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to some of the subjects in the Hokanson studies could have acted as such markers. Exercise could also, as discussed earlier, suggest the completion of a threatening encounter, as the stress response primarily facilitates physical action. It is possible that the recovery process does not really begin until the threat has demonstrably been overcome. Research shows that we are more likely to remember tasks that have not been completed, a phenomenon known as the Zeigarnik effect (Zeigarnik, 1927). Lewin (1927) has suggested that this enhanced memory is mostly a product of the tension created by leaving a task incomplete. It is likely, then, that stressors in particular would continue to produce tension until fully addressed and completed. This may be why distractions produce some alleviation in the short-term, but that, without some sort of cognitive restructuring, they do not offer lasting resolution of stress. Clearly many of these questions cannot be answered without more targeted research. It is unclear whether the benefits of cognitive flexibility come solely from restructuring the way one thinks about a stressor, or if being able to shift the topic of one’s thinking – that is, distracting oneself – confers the same benefits. Also, while a forgiving personality has been linked to better health, it is not entirely clear how this occurs. To date, no studies have examined actual offense and forgiveness in the lab to assess their effects on cardiovascular parameters. Further investigation of activities such as exercise and music could further illuminate how these aid recovery, and speak to whether they primarily influence mood through endorphins or other physiological mechanisms or whether they also influence cognitions. Furthermore, it remains unclear exactly what processes are involved in forgiveness. It could be that to be effective, forgiveness requires that one shift attribution from malicious intent to a product of circumstance, and this cognitive restructuring enables recovery and aids in feelings of completion. It could also be that forgiveness instead requires the ability simply to move on, and no longer dwell on the offense, and this cognitive distancing facilitates recovery. Investigating these possibilities could shed light not only on what constitutes forgiveness, but also the factors that are most important in recovery. Generating physiological responses to external threats is clearly an adaptive response. Research on the role of recovery in disease etiology, however, emphasizes that the stress response is not the only important adaptation we make in response to a threat. Just as important as changing our physiology to cope with, or even survive, the threat is the ability to assess when a threat is no longer present, and be able to return to baseline functioning. Without this accompanying shift, the ability to interpret and respond to a threat can become more damaging than protective. The importance of recovery is further magnified by the fact that many modern threats are of a diffuse, vague, social nature, without a clear stopping point. This makes the processes and effects of cognitive distancing and restructuring especially important in long-term cardiovascular responses, and consequently the development of cardiovascular disease. References Berkman, L.F., Blumenthal, J., Burg, M., Carney, R.M., Catellier, D., Cowan, M.J., et al., 2003. Effects of treating depression and low perceived social support on clinical events after myocardial infarction: the enhancing in coronary heart disease patients (ENRICHD) randomized trial. Journal of the American Medical Association 289 (23), 3106–3116. Berry, J.W., Worthington Jr., E.L., 2001. Forgivingness, relationship quality, stress while imagining relationship events, and physical and mental health. Journal of Counseling Psychology 48 (4), 447–455. Brosschot, J.F, Gerin, W., Thayer, J.F., 2006. The perseverative cognition hypothesis: a review of worry, prolonged stress-related physiological activation, and health. Journal of Psychosomatic Research 60, 113–124. Campbell, R.S., Pennebaker, J.W., 2003. The secret life of pronouns: flexibility in writing style and physical health. Psychological Science 14 (1), 60–65. Chafin, S., Roy, M., Gerin, W., Christenfeld, N., 2004. Music can facilitate blood pressure recovery from stress. British Journal of Health Psychology 9 (3), 393–403.
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