Defined as a inert medication used for psychological effects, or for purposes of comparison in an experiment.

Placebo-controlled studies are important in the evaluation of the effectiveness of medical treatments.

Separate specific and non specific effects, including placebo effects, regression to the mean, and natural course of a disease.

Reduces bias by enabling blighting of participants and if possible, of providers and assessors of outcome.

A tool to determine whether a treatment truly works.

Responses to placebo varies with type of placebo, how treatment is provided and whether informed consent was involved.

Placebo responses could be of major importance in conditions in which cognitive and emotional processes have a central role, such as an chronic pain or depression studies.

Molecular events and neural network changes underlying placebo and nocebo effects are mediated by anticipated future outcomes.

These expectancy’s are affected by how a medication or treatment is framed.

Suggestions about side effects can become self-fulfilling such as with pain, itchiness, nausea, or erectile dysfunction.

Negative expectancy can be significant influence in a patient’s evaluation of an analgesic effect.

Learning and classical psychological conditioning play roles in both placebo and nocebo effects.

The nucleus accumbens activates in the anticipation of effectiveness of a drug when given a placebo, indicating a its contributing role  in the placebo effect.


Prior therapy experiences drive nocebo effects: 30% of women undergoing chemo therapy for breast cancer have anticipatory nausea when exposed to neutral environmental cues, after repeated venipunctures neonates cry and  show pain behavior as soon as their skin is cleaned.

Trust in the clinician and a positive relationship, with open communication between physician and patient palliates symptoms.

Clinicians empathy reduces level of objective measures of inflammation  such as interleukin-8 in neutrophil count.

Positive expectations on the part of a clinician play a role in placebo effect.

The mass media and leg press, and the Internet, and direct exposure to others can foster nocebo responses.

Observing pain relief in others elicits placebo analgesic effects that are  similar in magnitude to the analgesic effects induced by previous first hand therapy.

Similarly, witnessing a person who reports side effects of a placebo, reports pain from the application of an inert ointment or inhales room air  that is described as potentially toxic causes side effects in participants who are exposed to the same placebo agents.

Clinical relationship such as perceived empathy, trust, connection, and expectations can influence clinical outcomes.

Physician’s beliefs about treatment efficacy and how they interact with patients can impact patient outcomes beyond the specific treatment.

When cues in the environment, or taste cues are paired with morphine, the same cues subsequently paired with placebo rather than morphine can produce analgesia.

Among patients with psoriasis in whom reduce glucocorticoid dosees were interspaced with placebo, relapse rates were similar to the rates among patients who receive full dose steroids.

In groups undergoing same glucocorticoid tapering regimen but without interspersed placebo, the relapse rate was three times as high as in the group that received dose extending placebo.

Similar placebo condition effects have been reported for chronic and insomnia and amphetamine treatment.

Nocebo effects are more likely to occur in those who are more anxious, have medically unexplained symptoms, or have greater psychological distress.

The addition of a placebo has been shown to enhance the beneficial effects of active drugs.

In the presence of worrisome information, mistaken beliefs, pessimistic expectations, negative prior experiences, they can lead to side effects and reduced benefits of symptomatic and palliative treatments.

Nonspecific side effects of drugs such as intermittent, idiosyncratic or not dose dependent effects that are are not reliably reproducible, are common.

When these side effects occur they may lead to nonadherence or drug discontinuation, substitution of another agent, or additional medications to treat the side effects, explained as nocebo effect.




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