Objective Quality of life is often impaired in patients with known hypertension, but it is less or not at all reduced in people unaware of their elevated blood pressure. Some studies have even shown less self-rated distress in adults with elevated blood pressure. In this substudy of the nationwide German Health Interview and Examination Survey for Children and Adolescents (KIGGS), we addressed the question whether, also in adolescents, hypertensive blood pressure is linked to levels of distress and quality of life.
Methods Study participants aged 11 to 17 years (N = 7688) received standardized measurements of blood pressure, quality of life (using the Children’s Quality of Life Questionnaire), and distress (Strengths and Difficulties Questionnaire).
Results Elevated blood pressure was twice as frequent as expected, with 10.7% (n = 825) above published age-, sex- and height-adjusted 95th percentiles. Hypertensive participants were more likely to be obese and to report on adverse health behaviors, but they showed better academic success than did normotensive participants. Elevated blood pressure was significantly and positively associated with higher self- and parent-rated quality of life (for both, p ≤ .006), less hyperactivity (for both, p < .005), and lower parent-rated emotional (p < .001), conduct (p = .021), and overall problems (p = .001). Multiple regression analyses confirmed these findings.
Conclusions Our observation linking elevated blood pressure to better well-being and low distress can partly be explained by the absence of confounding physical comorbidity and the unawareness of being hypertensive. It also corresponds to earlier research suggesting a bidirectional relationship with repressed emotions leading to elevated blood pressure and, furthermore, elevated blood pressure serving as a potential stress buffer.
In this substudy of the KiGGS survey, we have examined the association of elevated blood pressure with psychological distress and health-related quality of life in a large, nationally representative sample of German adolescents aged 11 to 17 years. In 825 of 7688 study participants (10.7%), elevated blood pressure levels above published age-, sex-, and height-adjusted 95th percentiles were documented by means of standardized oscillometric measurement, demonstrating twice the rate expected from earlier normative samples (28). Hypertensive blood pressure was independent of socioeconomic status and most frequently found in postpubertal boys.
The central finding of this investigation was that adolescents with elevated blood pressure levels reported significantly better quality of life and lower levels of distress on multiple domains of two well-validated instruments. Moreover, concordant results were observed for both self- and parent-rated versions of the two instruments and for both systolic and diastolic blood pressure as predictors. All associations remained stable when adjusted for a variety of possible confounders in multivariate analyses. These observations in adolescents seem to contradict several reports from adult patients who are aware of having arterial hypertension. The adult patients may already feel concerned about possible long-term health complications, the necessity of regular visits to a physician, and costs and adverse effects of antihypertensive medication. Together with hypertensive end-organ damage present sometimes, this may impair quality of life (1,12,20).
In contrast, our results confirm earlier studies in adult populations showing an inverse association between hypertension and subjectively measured distress (19,20). For example, Winkleby et al. (19) found that hypertension as defined by elevated office blood pressure and/or current use of antihypertensive medications was negatively related to an index of self-rated job stressors in 1428 San Francisco bus drivers, and the same effect was observed also for continuous blood pressure values. Remarkably, this inverse association was equally found in nonmedicated (and possibly unaware) and medicated (and probably aware) participants.
Most of the hypertensive adolescents identified in the KiGGS study were not aware of their elevated blood pressure, which was only detected by routine screening performed as part of this survey. It is well known that individuals unaware of having high blood pressure usually report less bodily pain and show higher scores in physical functioning and general health than those with known hypertension (1,20,35,36). However, this putative unawareness does not explain why elevated blood pressure was actually associated with better quality of life and lower distress. Several possible explanations might account for this inverse association observed in our sample. a) Some adolescents may be more achievement oriented and, thereby, more successful in their school careers than others. This may occur at the expense of chronic (objective) stress and elevated blood pressure but lead to better self-esteem and quality of life. b) Repression of emotions may lead to better self-ratings of distress and quality of life, and repressed emotions might at the same time lead to elevations in blood pressure, as suggested by a line of research recently summarized by Mann (37). c) Elevations in blood pressure themselves might dampen negative emotions, possibly via vagal afferents. These three possible explanations are not mutually exclusive, and each one merits further discussion. However, the cross-sectional nature of our data does not allow us to draw firm causal conclusions.
In our sample, hypertensive participants performed better at school than did normotensive participants. Better school performance was associated with both better quality of life (data not shown) and elevated blood pressure. However, good quality of life was not mainly driven by better school success because elevated blood pressure and quality of life remained positively associated even after controlling for irregular school career. School success may, on the other hand, have been achieved at the expense of an increased stressor burden contributing to both high blood pressure and adverse health behaviors.
Our data are also consistent with the emotion repression theory of hypertension. Following that theory, repressed emotions, which could manifest themselves in low self-rated distress, might drive blood pressure up, probably via autonomic arousal (38). Interestingly, however, also parents of hypertensive adolescents rated their children as less distressed, less hyperactive, and more satisfied with their lives than did parents of normotensive adolescents. This indicates that not only hypertensive adolescents themselves but also their close family members perceived them as less distressed. Whether this means that repression of emotion in adolescents leads to distorted perception in their parents via changes in adolescents’ expressive behavior or whether these parents are repressors themselves, unable to recognize negative emotional clues in their children, cannot be concluded from our data.
Finally, our data could reflect a repeatedly described stress-dampening effect of hypertension (37,39–41). Arterial mechanoreceptors in the aortic arch and carotid sinus, which are sensitive to changes in systemic blood pressure, function as key elements in the transmission of hemodynamic information to the brain via vagal afferents. From some experimental studies performed almost 20 years ago, it is well documented that elevated blood pressure can thereby have pain- and stress-lowering effects (38–43). Previous reports have suggested the presence of an inhibitory feedback loop for adaption to chronic stressors, in which activation of baroafferent pathways by mechanical stretch caused by elevated blood pressure reduces somatic muscle tone, increases cortical synchronization, and blunts the level of pain and anxiety, all of which may have a beneficial impact on emotional well-being but may also lead to the transition of stress-induced hypertensive reactions to sustained chronic hypertension (38,44). Provided that a rise in blood pressure is involved in the reduction of perceived stress, the endogenous baroreceptor-brain circuitry constitutes a reinforcing mechanism, which rewards phasic elevations of blood pressure in stressful conditions, a reaction that could be learned over time (39). More recently, it has been shown that exogenic stimulation of the vagus nerve may have anticonvulsive and antidepressant properties (45). Interrupting the baroreceptor-brain circuitry by antihypertensive drug therapy, on the other hand, commonly reduces health-related quality of life and, possibly, also may impede adherence to pharmacological treatment (46).
There are some limitations to this study, mainly based on its cross-sectional and post-hoc design, which does not allow a causal interpretation for the observed link between high blood pressure and quality of life. Because the survey was originally not planned to specifically examine associations between blood pressure and well-being, no ambulatory blood pressure monitoring is available. However, the blood pressure readings in KiGGS were obtained under highly standardized conditions by trained physicians and with devices well validated for this age group. They have been published and accepted as new reference values for German children and adolescents (25). Nevertheless, the assignment to the hypertensive group was not based on a medical diagnosis, but on blood pressure levels above previously reported age-, sex-, and height-adjusted 95th percentiles, determined during one complex and potentially demanding diagnostic assessment. They are likely to be biased in the same way as typical office blood pressure recordings are. The unexpectedly high prevalence of elevated blood pressure found in this study cohort should therefore be interpreted with caution. Finally, the effect sizes of systolic and diastolic blood pressure on quality of life were small. However, they were still within the range of other known determinants for health-related quality of life, such as sex, body weight, and alcohol consumption. The small effect sizes may be caused by the relatively small range of blood pressure values and to sample heterogeneity; however, the highly consistent findings across self-rating and parent rating on several dimensions of distress and quality of life suggest a real and epidemiologically relevant association.
Our investigation also has several strengths. Data were available for a large, representative and well-characterized sample, giving sufficient statistical power and generalizability to our observations. Another strength is the well-standardized assessment of blood pressure, quality of life, and distress as well as the use of individual norm-based blood pressure cutoffs rather than one simple threshold. Our analysis was based on the widely accepted reference from the National High Blood Pressure Education Program Working Group on Children and Adolescents (28) because this reference also included overweight individuals, and, moreover, used relatively high cutoff levels (26). The results found for categorized blood pressure data were fully confirmed with continuous readings for both systolic and diastolic blood pressure as predictors in multivariate models, which were adjusted for a variety of possible confounders. Furthermore, we obtained psychometric evaluations by both adolescents and their parents, using instruments that had been well validated beforehand and applied independently of the authors of this substudy, who we were not involved in data collection.
In summary, in this representative sample of German adolescents, we demonstrate a significant and epidemiologically relevant association of hypertensive blood pressure with lower psychological distress and better health-related quality of life. To our knowledge, this is the first report linking elevated blood pressure to quality of life and psychosocial adaptation in a large epidemiological study of adolescents. Besides the absence of confounding from physical comorbidity and a formal diagnosis of hypertension, our cross-sectional assessment may capture a stress-dampening effect of high blood pressure or effects of repressed emotions on blood pressure already at an early stage, not yet fixed by vascular remodeling.