Placebo effects on nausea and motion sickness are resistant to experimentally-induced stress.

Nausea often occurs in stressful situations, such as chemotherapy or surgery. Clinically relevant placebo effects in nausea have been demonstrated, but it remains unclear whether stress has an impact on these effects. The aim of this experimental study was to investigate the interplay between acute stress and placebo effects in nausea. 80 healthy female volunteers susceptible to motion sickness were randomly assigned to either the Maastricht Acute Stress Test or a non-stress control condition, and to either placebo treatment or no treatment. Nausea was induced by a virtual vection drum and behavioral, psychophysiological as well as humoral parameters were repeatedly assessed. Manipulation checks confirmed increased cortisol levels and negative emotions in the stressed groups. In the non-stressed groups, the placebo intervention improved nausea, symptoms of motion sickness, and gastric myoelectrical activity (normo-to-tachy (NTT) ratio). In the stressed groups, the beneficial effects of the placebo intervention on nausea and motion sickness remained unchanged, whereas no improvement of the gastric NTT ratio was observed. Results suggest that placebo effects on symptoms of nausea and motion sickness are resistant to experimentally-induced stress. Stress most likely interfered with the validity of the gastric NTT ratio to measure nausea and thus the gastric placebo effect.

The suffering ape hypothesis.

The "fearful ape hypothesis" could be regarded as one aspect of a more general "suffering ape hypothesis": Humans are more likely to experience negative emotions (e.g., fear, sadness), aversive symptoms (e.g., pain, fever), and to engage in self-harming behavior (e.g., cutting, suicide attempts) because these might motivate affiliative, consolatory, and supportive behavior from their prosocial environment thereby enhancing evolutionary fitness.

Therapeutic encounters and the elicitation of community care.

Singh's analysis of shamanism is regarded as a contribution to the evolutionary study of healing encounters and evolutionary medicine. Shamans must create convincing healing spectacles, while sick individuals must convincingly express symptoms and suffering to motivate community care. Both have a shared interest in convincing onlookers. This is not restricted to shamanic treatment, but is still true in modern medical care.

The Signaling Theory of Symptoms : An Evolutionary Explanation of the Placebo Effect.

Placebo research shows that the subjective quality of care and social support, as well as the patients' expectations of treatment, influence therapeutic outcomes. However, this phenomenon, known as the placebo effect, does not usually cure the disease, but rather can provide symptomatic relief: It may soothe symptoms such as pain, swelling, or nausea that constitute part of an immune response. The function of this mechanism remains unclear. This article puts forward the Signaling Theory of Symptoms (STS) as a possible explanation. According to STS, discernible aspects of an immune response, such as pain, swelling, or nausea, not only serve a defensive and healing function but also a signaling function: symptoms signal the need for care and treatment to potential helpers. Once help and treatment are granted, the signaling function is fulfilled and the symptoms diminish. This mechanism may have been a significant advantage in preindustrial environments, when sufferers depended on extensive social support and personal treatment. Nowadays, from the point of view of modern materialist medicine, the mobilization of social support no longer seems so crucial, and thus the placebo effect has been assigned a somewhat mysterious quality.

Enhancing drug compliance and the placebo effect by raising subjective expectations.

Increasing the patient's subjectively felt effectiveness of a treatment might be a key to enhanced drug compliance and placebo effects, and may in this way enhance the effectiveness of medical treatment at a low cost. Simple methods to achieve this aim are suggested, derived from consumer psychology, psychology of judgement and user-centered design. A drug's design should meet three criteria: an intuitive design which makes the purpose of the drug easily discernible, confirmatory side effects which give feedback that matches the drug's purpose, and mental models which enable the patient to develop an understanding of the drug's mechanism of action.