Presentation on theme: "Mind Over Matter: Placebos and Expectancies Quiz! 1.T/F: Placebos make patients feel better; they don’t actually get better 2.T/F: There are no negative."— Presentation transcript:
Mind Over Matter: Placebos and Expectancies
Quiz! 1.T/F: Placebos make patients feel better; they don’t actually get better 2.T/F: There are no negative effects of placebos 3.T/F: Placebos can reduce asthma and make wounds heal faster 4.T/F: Placebo therapy could be the end of biomedicine as we know it 5.T/F: Doctors can lie to patients if it is in the patient’s best interest.
Placebo From Latin placere - “to please” or “I will please” Placebo –“an innocuous substance without a specific physiological effect” Clearly active and not innocuous; has physiological effects –any treatment devoid of specific actions on the patient’s symptoms or diseases that, somehow, can cause an effect upon the patient. Obviously have specific actions but true that we don’t know precisely how
The Placebo Effect Based on expectancies –"anticipation of a systematic if/then relationship between events and objects." (Tolman, 1932) Afflictions that have strong psychological components (pain, anxiety, and depression) tend to show high rates of placebo effects –~ 65% of patients in antidepressant trials get better with drug –~ 35% of patients in antidepressant trials get better with placebo –Many times these rates don’t differ statistically (30% rule) A meta-analysis showed that antidepressants relied on the placebo effect for 75% of their effectiveness The remaining 25% “real” drug effect may be a disguised placebo effect
The Placebo Effect (cont) Blocked by real drugs, e.g., opioid antagonists Placebos have side effects (nocebo) Placebo effects can last for a long time: over 8 weeks for panic disorder, 6 months for angina pectoris, and 2.5 years for rheumatoid arthritis. Depressed patients who respond to placebos differ biochemically from those who don’t –Short-term depression (< 3 months) more responsive –Long-term depression (> 1year) not responsive
Placebo Effect If expectation of pain can increase pain intensity, –how might expectation of pain reduction influence perception? Experimental results –85% of Ss given placebo for relief of pain caused by Herpes (cold sores or genital sores) reported pain reduction –56% of patients given sham treatment (small skin incision) for angina (heart pain) reported significant pain reduction –On average, 33% of Ss in placebo pain studies report pain reduction
Are many drug effects simply placebo effects? Placebo effects were discovered in the 1950s –Administering a simple sugar pill or water alleviated symptoms or even cured some diseases However, it’s a minority view that it’s all placebo Nonetheless, some placebo effects may be present in all drug effects –How do you dissociate placebo from other effects?
Nocebo (“I will harm”) (Walter Kennedy, 1961) A nocebo response occurs when a drug- trial's subject's symptoms are worsened by the administration of a placebo. If the patient believes a substance is harmful it can cause negative effects.
The Nocebo Effect Emotional state, depression, anxiety, anger, hopelessness Negative health care provider No love in the family Cynicism, suspicion and pessimistic expectations Medical students disease (hypochondriasis) Cardiac neurosis is a nocebo – 75% of chest pain is due to anxiety.
Nocebo Effect Approximately ¼ of patients receiving a placebo voluntarily report adverse side effects When prompted, between 27% and 71% report adverse side effects Usually general complaints (difficulty concentrating, nausea, fatigue)
Placebo/Nocebo Evidence Based Medicine All drugs and procedures need to be tested against the placebo/nocebo effect, as high as 70% in most medications and operations. Treatment benefit = therapeutic gain + natural history of illness + placebo effect-nocebo effect
Note that if the nocebo effect is greater than the therapeutic gain and the natural history of the disease, the treatment will make the patient worse. The evil eye – voodoo – witchcraft
Dealing with Placebo and Nocebo Effects in Experiments Study Designs (randomly assigned to experimental/placebo arms; passive vs active placebos) Blinded Study- Participant doesn’t know if they are receiving treatment or placebo Double-Blinded Study- Participant and Experimenter do not know if treatment or placebo is being given Double-Blind, Crossover Study- Same as double-blinded, except participants get treatment and placebo in random order (controls for Ss variability)
Ethics of Clinical Studies Is placebo ethical? Is prescribing placebos deceitful or unethical? Sometimes standard therapies are found to be dangerous
Source of Placebo: Pavlovian Conditioning
Why the high responsiveness to expectation of pain relief? Evidence that expectation of pain relief activates mu- opioid neurotransmitter system (“endorphins”) Zubieta et al - Placebo Effects Mediated by Endogenous Opioid Activity on µ-Opioid Receptors (2005) Red & orange indicate regions of heightened mu- opioid activity when P reports positive effect of placebo
Other factors involved in the placebo effect (cont) Natural disease progression may be cyclical – gets worse then gets better Enrolling in a clinical trial or seeing a doctor gives some individuals a greater sense of control over the illness Feelings of concern and caring from nurses, doctors, and researchers –A healing environment Difficult to measure some illnesses/diseases –Scales for measuring pain/anxiety/depression are not clear cut and tend to be somewhat labile Poor patient selection (no test for susceptibility to placebo)
Cognitive Explanations: Schemata Organized representations of conceptually-related information that guide processing of new information –Facilitate memory and comprehension –Influence the speed of information processing and problem solving –Gather information into meaningful and more easily retrieved units –Enable the individual to fill in missing information –Provide greater confidence in prediction and decision making.
Creating Expectations: Alcohol Identified in various age, drinker groups Alcohol schemas in pre-schoolers Related to drinking levels Predicts future drinking levels Change in parallel with drinking levels Experimentally manipulable with corresponding effects on drinking Consistent with behavior after drinking Some relationship with family history Change with age before drinking
Development of Alcohol Expectancies
Alcohol Expectancies (cont) With age and drinking, alcohol expectancies have more to do with arousal/sedation than whether alcohol is good or bad