The role of cognitive impairment in the placebo and nocebo effects

The psychosocial context surrounding the patient and the psychobiological model do offer interesting perspectives from which to study the placebo response. The term 'response' should only be reserved for an active neurobiological process that occurs as a result of a dummy treatment. The context surrounding the administration of a placebo can also lead individuals to expect a worsening of symptoms; indeed changes in the negative direction are observed as part of the nocebo effect. One way of studying nocebo effects after medical treatment is to analyse the findings of randomised double-blind placebo-controlled trials. The importance of these studies is given by their attempt to maximise the placebo components of therapies and thus to minimise the worsening of symptoms. Assessing situations where loss of placebo mechanisms may require increased therapeutic dosage represents another crucial aspect. These aspects become even more important in patients with dementia, who may exhibit a disruption of the expectancy-evoked placebo-analgesia network and impaired sensory and affective responses to pain. In this chapter we attempt to answer specific questions with regard to patients with cognitive impairment, even though at present we only have a limited understanding of the factors that influence patients' response to pain and to placebo treatment