November 16, 2009Health Psychology Placebos do these definitions rule out active agents? many argue that placebo really accounts for a large part of any therapeutic procedure, active or not! defining the terms specific effects versus non-specific effects how do we know? placebo vs. active treatment designs ? ?randomized controlled trial? fully crossed designs Placebo and pain much of the early work focused on pain what is relation of placebo to various pain medications? (k = number of studies testing analgesic versus placebo) morphine: 56% (k=6) aspirin: 54% (k=9) darvon: 54% (k=2) codeine: 565 (k=2) zomax: 55% (k=3) you get more pain relieve when you think you are getting stronger pain reliever compared to when you think you are getting a weaker drug Placebo effects so, is it just pain or what? recent work suggests non-specific effects can occur in a variety of systems Where can we observe placebo effects? hypertension, stress, cardiac pain, blood cell counts, headaches, papillary dilation autonomic nervous system adrenal gland secretion, diabetes, ulcers, gastric secretion and motility, colitis, oral contraceptives, menstrual pain endocrine system common cold, fever, vaccines, asthma, multiple sclerosis, rheumatoid arthritis, warts, cancer immune system surgical treatments biofeedback instrumentation, medical instrumentation of all sorts psychological treatments such as conditioning, psychotherapy more generally health behaviors non-pharmacological insomnia techniques psychotropic drugs for treatment of depression Role of placebo in pharmacological treatment of depression the correlation between drug response and placebo response is tremendously high r = .90 (c<.001) indicates that the placebo response is proportional to the drug response clarifying drug effect and drug response placebo conditions show about 75% of the drug response that is, people on inactive placebo show between 74% and 76% of the benefit of those receiving the active drug The role of belief if a patient/person believes that an agent or activity is going to help them, they will experience a placebo effect, regardless of the actual efficacy of the treatment if a patient/person believes that an actual (active) therapeutic treatment will help, their placebo response will facilitate whatever actual effect the treatment possesses if a patient/person believes that an actual (active) therapeutic treatment will NOT help, their placebo response will suppress/oppose whatever actual effect the treatment possesses (often called the ?nocebo? reponse) Other placebo factors format important ?medical-ness,? pill size/color, credibility side effects induced and active placebos Active Drug No Active Drug Believes Drug (placebo) Total effect (drug + placebo) Placebo (no drug + placebo) Believes NO Drug (no placebo) Pure drug (drug ? placebo) (null effect (no drug or placebo)
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