Suzanne G. Helfer

Goal activation, expectations, and the placebo effect.

Motivational factors receive little attention in current theories of the placebo effect. Reasons for this position are reviewed, and an argument is made for reconsidering the influence of motivation on the placebo effect. The authors hypothesize that nonconscious goals alter reactions to a placebo expectation. Specifically, the authors predict that the placebo effect is most likely to occur when individuals have a goal that can be fulfilled by confirmation of the placebo expectation. The authors tested this notion in 5 experiments. The results demonstrate the role of motivation in the placebo effect across a variety of symptom domains and via 4 different goal activation techniques. Moreover, this moderating effect occurred for both positive and negative placebo expectations, across different placebo effect measures, and in brief laboratory experiments as well as in lengthier studies. It is argued that theories regarding the placebo effect should incorporate motivational factors.

Dispositional Optimism Predicts Placebo Analgesia

UNLABELLED Based on prior research identifying dispositional optimism as a predictor of placebo responding, the present study tested the hypothesis that individuals high in optimism would be more likely to respond to a placebo analgesic. Optimists and pessimists were randomly assigned to a placebo expectation condition or a no expectation condition before a cold pressor task. Blood pressure and heart rate were recorded before and during the cold pressor task, and participant ratings of pain and expectations were obtained immediately after the task. Analysis of the expectation manipulation revealed that the placebo instruction was successful in altering participant expectancy during the cold pressor. Supporting the main hypothesis, dispositional optimism was associated with lower pain ratings in the placebo condition but not in the control condition. Because dispositional optimism can alter placebo responding to laboratory pain, future studies should examine the potential role that this individual difference factor may play in patient responsivity to pharmacological and nonpharmacological treatments for clinical pain. PERSPECTIVE This study examined the possibility that individual differences can predict placebo analgesia. Participants were randomly assigned to receive either a placebo expectation or no expectation before a cold pressor task. Dispositional optimism was related to less cold pressor pain in the placebo condition as compared with the control condition.

Expectations and Placebo Response: A Laboratory Investigation into the Role of Somatic Focus

It has been theorized that expectations are an important causal determinant of the placebo effect. Placebo expectations, however, do not always yield placebo effects. In a laboratory study, we tested the hypothesis that ones level of somatic focus moderates the effect of placebo expectations on placebo responding. We also varied whether participants were told the placebo was a drug, could either be a drug or placebo, or was a placebo. The results revealed that individuals who thought they were taking a drug (i.e., unconditional expectations) reported more placebo symptoms when they closely focused on their symptoms. Individuals told they may or may not be receiving a drug (i.e., conditional expectations) did not differ from control participants regardless of how closely they attended to their symptoms. The findings have theoretical implications for expectancy models of the placebo effect as well as for practical research comparing the type of expectations held by individuals in clinical trials and clinical practice.

Dispositional Optimism and Thoughts of Well-Being Determine Sensitivity to an Experimental Pain Task

BackgroundPrior studies with patient samples have found dispositional optimism to be associated with less pain.PurposeWe examined the relationship between optimism and experimental pain. It was hypothesized that optimists generally cope with a painful stimulus by mentally disengaging from the pain. However, if optimists are prompted to think about health and well-being prior to the painful event, they are more responsive to the pain.MethodsOptimists and pessimists were primed with words related to health or with neutral words prior to the cold pressor task. Pain, distress, and cardiovascular reactivity to the cold pressor task were assessed.ResultsDispositional optimism was associated with lower pain sensitivity, distress, and cardiovascular reactivity in the neutral prime condition. In the health prime condition, optimists and pessimists did not differ on any of the dependent measures.ConclusionsDispositional optimism is associated with reduced pain for healthy adults encountering a brief pain stimulus. This relationship is eliminated, however, when individuals are primed with thoughts of health and well-being. The results are interpreted as evidence for the use of differential coping strategies by optimists in response to pain.

Opioid Analgesia in Persons at Risk for Hypertension

Objective: Acute pain sensitivity is reduced in clinical hypertension, but the precise relationship between pain perception and altered blood pressure control is not well-characterized. A negative correlation between resting blood pressure and pain sensitivity is observed throughout the normotensive range, suggesting links between basic mechanisms of blood pressure control and pain regulation. The opioid peptides are important endogenous analgesic mechanisms, but their role in the hypoalgesia of blood pressure elevations has not been well-established. The current study sought to examine the effects of endogenous opioids on blood pressure-associated hypoalgesia in young adults at risk for hypertension development. Methods: The effects of the opioid receptor antagonist, naltrexone, on cold pressor pain sensitivity were assessed in young adult men (n = 49) and women (n = 76) with mildly elevated casual blood pressure. Results: Results indicate interactions between hypertension risk and the effects of opioid blockade on pain sensitivity. Conclusions: These findings suggest exaggerated opioid analgesia in persons at enhanced risk for hypertension and point to important links between altered neuropeptide regulation of pain and altered blood pressure control mechanisms in the early stages of hypertension. HR = heart rate; SBP = systolic blood pressure; DBP = diastolic blood pressure; MAP = mean arterial pressure; HPA = hypothalamic pituitary adrenocortical; CRF = corticotropin-releasing factor.

Why does choice enhance treatment effectiveness? Using placebo treatments to demonstrate the role of personal control

In modern health care, individuals frequently exercise choice over health treatment alternatives. A growing body of research suggests that when individuals choose between treatment options, treatment effectiveness can increase, although little experimental evidence exists clarifying this effect. Four studies were conducted to test the hypothesis that exercising choice over treatment alternatives enhances outcomes by providing greater personal control. Consistent with this possibility, in Study 1 individuals who chronically desired control reported less pain from a laboratory pain task when they were able to select between placebo analgesic treatments. Study 2 replicated this finding with an auditory discomfort paradigm. In Study 3, the desire for control was experimentally induced, and participants with high desire for control benefited more from a placebo treatment when they were able to choose their treatment. Study 4 revealed that the benefit of choice on treatment efficacy was partially mediated by thoughts of personal control. This research suggests that when individuals desire control, choice over treatment alternatives improves treatment effectiveness by enhancing personal control.

Elevated resting blood pressure and dampened emotional response.

Objective: Increased blood pressure is associated with decreased reports of aversiveness for both physical pain and psychosocial stressors. Based on these findings, higher blood pressure could be associated with altered emotional responses to a broader range of stimuli. There are at least 3 ways this could happen: a) less dire response to negative stimuli with no change in response to positive stimuli; b) more positive responses to both negative and positive stimuli; or c) dampened emotional responses to both positive and negative stimuli. Methods: Sixty-five normotensive volunteers had their resting blood pressure measured, then rated their emotional responses to a series of positive and negative photographs. Results: Resting systolic blood pressure was significantly and negatively correlated with subjective emotional ratings of both positive (r = −.26) and negative (r = −.35) photographs. Conclusion: Results were consistent with emotion dampening for elevated resting blood pressure and may reflect homeostatic integration of neurocirculatory control and affect regulation.

Concept priming and pain: an experimental approach to understanding gender roles in sex-related pain differences

Prior research has found that sex differences in pain are partially due to individual variations in gender roles. In a laboratory study, we tested the hypothesis that the presence of covert gender role cues can also moderate the extent to which women and men experience pain. Specifically, we varied gender role cues by asking male and female participants to write about instances in which they behaved in a stereotypically feminine, masculine, or neutral manner. Pain and cardiovascular reactivity to the cold pressor task were then assessed. Results revealed that, when primed with femininity, men reported less pain and anxiety from the cold pressor task than women. However, no differences existed between the sexes in the masculine or neutral prime conditions. The results indicate that covert gender cues can alter pain reports. Further, at least in some situations, feminine role cues may be more influential on pain reports than masculine role cues.

Does gender affect the relation between blood pressure and pain sensitivity

High resting blood pressure is associated with decreased pain sensitivity. This study was designed to explore this relation in young, normotensive men and women. Twenty-nine women (mean age 19.1, range 18-29) and 26 men (mean age 19.3, range 18-25) rested for 10 min while systolic, diastolic, and mean arterial blood pressures were measured. They were then asked to complete a 2-min cold pressor task. Participants were asked to fill out the short form of the McGill Pain Questionnaire immediately after the pain task. Hierarchical regression analyses were performed to predict pain sensitivity from resting blood pressure, gender, and the interaction of resting blood pressure and gender. Resting systolic blood pressure was a significant predictor of pain sensitivity. Gender and the interaction between resting blood pressure and gender were not related to pain sensitivity. This suggests that the relation between resting blood pressure and pain sensitivity may be similar in men and women, at least in response to a cold pressor challenge.

Effect type but not attribute framing alters nocebo headaches in an experimental paradigm.

Practitioners and clinical researchers are ethically bound to inform individuals about possible undesired treatment effects; however, the very provision of this information risks elevating the likelihood of those adverse effects, a phenomenon called the nocebo effect. Developing experimental models of this phenomenon and identifying communication strategies that minimize and perhaps even prevent nocebo effects would provide opportunities to avoid this risk. In the present research, we established an experimental paradigm to investigate the influence of 2 types of verbal instruction on nocebo headaches. One hundred twenty-six participants were randomized into a 2 (Effect Type) × 2 (Attribute Framing) between-subjects design, with the addition of a no-headache-forewarning control group. The effect type manipulation compared the magnitude of nocebo effects when headaches were described as the primary effect or the side effect of a treatment. The attribute frame manipulation compared the magnitude of nocebo effects when headaches were described as either 70% likely to occur versus 30% unlikely to occur. Headache instructions increased headache reports compared with the no-headache-forewarning control condition. Further, primary effect participants reported headaches more than side effect participants. There were no effects of the attribute framing manipulation. The findings were consistent across measures of headache occurrence, frequency, and maximum level. Nocebo headaches can be obtained in a laboratory paradigm that includes a no-headache-forewarning control group. Effect type framing moderates nocebo headaches and this result can inform attempts at reducing nocebo effects in clinical practice. The findings have implications for the correspondence between nocebo research and clinical practice.