Almost everybody has experienced anxiety at some time in life, including persons with high blood pressure as well as those with normal blood pressure. Imagine the various sensations you experience if you are asked by a teacher to report to the class the basic conclusions from an article you were supposed to have read but did not. This experience of anxiety is comprised of a number of cognitive manifestations, including catastrophic thinking, anticipation of danger, and sensing doom, accompanied by a full array of physiological symptoms associated with sympathetic and somatic nervous system arousal, including increased heart rate, sweating, shortness of breath, muscle tension, and disturbances of the gastrointestinal system. The discomfort associated with the experience of these cognitive and somatic symptoms of anxiety often leads to behavioral escape or avoidance responses (for example, "I feel ill and need to go home"). Although anxiety is a normal emotion to experience in situations like this, when the experience of anxiety becomes too frequent or too intense and begins to interfere with daily functioning, diagnoses with a range of anxiety disorders can be made, including panic disorder, generalized anxiety disorder, and obsessive compulsive disorder. Although there have been reports of increased blood pressure among patients with anxiety disorders (Fontaine and Boisvert, 1982; White and Baker, 1987), the incidence of essential hypertension among anxiety disorder patients is no different from the population at large (Chapman et al., 1990). Because acute anxiety responses to stress are not typically measured in these reports, these studies provide very little information regarding the role of anxiety reactions in the etiology of essential hypertension.
To focus on state anxiety, if individuals who respond to environ mental stress with increased acute anxiety responses go on to develop high blood pressure, anxiety may be considered a component of the acute stress response that warrants further examination in understanding etiologic factors of hypertension. Let's consider the evidence for this association among both normotensive and hypertensive patient samples.
Acute Anxiety Responses and Blood Pressure among Normotensives Although correspondence between measures of state anxiety and blood pressure does not reflect a perfect correlation, these variables do tend to correlate in a small but positive way when applied in laboratory stress manipulations. For example, Turner, Beidel, and Larkin (1986) reported increases in both state anxiety and blood pressure in response to a social conversation task as well as an impromptu speech among both socially anxious and nonsocially anxious normotensive participants. There are countless additional studies like this in the assessment literature pertaining to anxiety disorders that show that indices of both state anxiety and blood pressure increase when exposed to fear-evoking stimuli, although correlations between response channels are often minimal or moderate at best (see Lang, 1978). Given the conclusions of these studies, it is generally accepted that exposure to fearful stimuli results in increases in both blood pressure and measures of state anxiety.
In two studies that measured state anxiety during high school health courses in which blood pressure determinations were made, state anxiety during blood pressure measurement was shown to correlate with both SBP and DBP among young black males, but only with SBP among white males (Johnson et al., 1987b) and black females, but not white females (Johnson, Schork, and Spielberger, 1987a). Most of these correlations, however, failed to achieve significance when controlling for traditional risk factors for essential hypertension like family history of essential hypertension, weight, and sodium intake. Therefore, while young adults, particularly young black adults, who express heightened state anxiety during blood pressure measurement sessions exhibited higher blood pressures than less anxious young adults, the association was explained by a number of other variables.
In summary, among persons with normal blood pressures, there is evidence indicating that conditions that arouse state anxiety also re-
suit in increased blood pressures (Lang, 1978). However, among studies that measure acute anxiety responses to stress among normoten-sives, there is no evidence that these acute state anxiety and blood pressure responses lead to sustained elevations in blood pressure. In fact, quite the contrary, the blood pressure elevations observed among these studies are typically temporary and return to normal shortly following the stressful encounter. In order to demonstrate a relation between acute state anxiety responses and the etiology of essential hypertension, case-control studies using hypertensive patients need to be examined.
Acute Anxiety Responses and Blood Pressure among Hypertensives With the knowledge that exposure to stressful stimuli results in increased state anxiety as well as blood pressures in non-hypertensive samples, several researchers began to test whether the magnitude of this observed increase in state anxiety was accentuated among samples of essential hypertensive patients or persons at risk for sustained hypertension, including borderline essential hypertensive patients. In accord with the hypothesis that the increased blood pressures observed in the clinic among isolated clinic ('white coat') hypertensive patients is related to anxiety surrounding the clinic visit, these patient groups have also been examined with respect to their acute anxiety responses to stress.
Comparable to findings using normotensives, measures of state anxiety during clinic visits of essential hypertensive patients have been shown to be related to blood pressure (Jeter, Bush, and Porter, 1988; McGrady and Higgins, 1990). Jeter et al. found that SBPs declined over multiple blood pressure determinations during a single clinic visit for both hypertensives and normotensives, and that these reductions in SBP were correlated with reductions in state anxiety. McGrady and Higgins reported that hypertensive patients, as determined by initial clinic measures of blood pressure, who exhibited reductions in blood pressure during weekly clinic visits over a period of six weeks (isolated clinic hypertensives) had higher measures of state anxiety during the initial clinic visit than patients with sustained levels of high blood pressure over the six weeks. These findings suggest that state anxiety may influence measurement of blood pressure in the clinic, obscuring accu rate diagnoses. Other studies contrasting patients with isolated clinic hypertension and patients with persistent hypertension on measures of state anxiety, however, have failed to detect any difference in state anxiety between these two groups (Larkin et al., 1998b; Siegel, Blumenthal, and Divine, 1990).
Additionally, in another study, exposure to a standard mental arithmetic stressor yielded a significant correlation between state anxiety and SBP response, but not DBP response, among a group of essential hypertensive patients (Aivazyan et al., 1988). Therefore, essential hypertensive patients appear to exhibit the same associations between state anxiety and blood pressure responses seen among normotensives when undergoing clinic blood pressure measurements or while being exposed to mental stress. However, because few of these studies employed a normotensive control group for purposes of comparison, little can be said regarding the potential role of state anxiety in the stresshypertension relation. If indeed the acute state anxiety response to stress is involved in onset of hypertension, it is important to demonstrate that the magnitude of state anxiety responses to stress is much greater among hypertensive patients than normal blood pressure controls.
In a study examining performance of hypertensive and nor-motensive patients on a variety of tests of memory and information processing, Blumenthal et al. (1993) found that hypertensive patients exhibited higher scores on a measure of state anxiety than normoten-sives. Crane (1982), likewise, found higher scores on state anxiety among hypertensive patients than normotensive counterparts. Other studies, in contrast, found no difference between hypertensive and normotensive volunteers using the same measure of state anxiety (Larkin and Zayfert, 2004; Russell, 1983). To complicate matters further, some studies have reported greater state anxiety responses among normotensive volunteers than their hypertensive counterparts (Ny-klicek, Vingerhoets, and Van Heck, 2001; Steptoe, Melville, and Ross, 1982).
Some studies have examined state anxiety among samples of borderline essential hypertensive patients (James et al., 1986; Perini et al., 1990). If stronger associations between state anxiety and blood pressure could be demonstrated among these patients than persons with normal blood pressures, an argument could be made that the linkage existed before onset of essential hypertension and may therefore be involved in its etiology. James et al. found a strong correlation between state anxiety and DBP during an ambulatory blood pressure recording period that was most dramatic among borderline hypertensive patients with labile blood pressures. Perini et al. contrasted a group of borderline hypertensive patients with a group of normotensives without a parental history of hypertension. Borderline hypertensive patients exhibited higher state anxiety responses to a standardized presentation of mental and physical stressors than the normotensive controls.
In summary, evidence examining the magnitude of the acute state anxiety response among hypertensive patients as well as borderline hypertensive patients has been mixed. Furthermore, data from patients with diagnosable anxiety disorders, who clearly exhibit elevated acute anxiety responses to feared stimuli on a regular basis, do not reflect an increased incidence of chronic hypertension (Chapman et al., 1990). Therefore, there is little evidence at this point in time supporting the hypothesis that hypertensive patients regularly exhibit elevated acute anxiety responses (state anxiety) to stress in comparison to nor-motensives.
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