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Efectul Placebo

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  SICLITARU ANDREEA MARIANAGrupa 16, Seria C, Medicina Generala26.08.2010LACE! E##ECT A placebo has been defined as a substance or procedure ... that is objectively without specific activity for the condition being treated . Under this definition, a wide variety of things can be placebos and exhibit a placebo effect. Pharmacological substances administered through any means can act as placebos, including  pills, creams, inhalants, and injections. Medical devices such as ultrasound can act as placebos. ham surgery, sham electrodes implanted in the brain, and sham acupuncture, either with sham needles or on fa!e acupuncture points, have all exhibited  placebo effects. he  physician has even been called a placebo# a study found that  patient recovery can be increased by words that suggest the patient $would  be better in a few days%, and if the patient is given treatment, that $the treatment would certainly ma!e him better% rather than negative words such as $ & am not sure that the treatment & am going to give you will have an effect . he placebo effect may be a component of pharmacological therapies' Pain !illing and anxiety reducing drugs that are infused secretly without an individual(s !nowledge are less effective than when a patient !nows they are receiving them. )i!ewise, the effects of stimulation from implanted electrodes in the brains of those with advanced Par!inson(s disease are greater when they are aware they are receiving this stimulation. ometimes administering or prescribing a placebo merges into fa!e medicine.he placebo effect has sometimes been defined as a physiological effect caused by the placebo, but Moerman and *onas have pointed out that this seems illogical, as a placebo is an inert substance which does not directly cause anything. &nstead they introduced the word meaning response for themeaning the brain associates with the placebo, which causes a physiological  placebo effect. hey propose that the placebo, which may be unethical, could be avoided entirely if doctors comfort and encourage their patients+ health. rnst and -esch also attempted to distinguish between the true and  perceived placebo effect, as they argued that some of the effects attributed to the placebo effect could be due to other factors. he word placebo, )atin for & shall please , dates bac! to a )atin translationof the ible by *erome. &t was first used in a medicinal context in the /0th century.he phenomenon of an inert substance resulting in a patient+s medical improvement is called the place$% e&&ec' . he phenomenon is related to the  perception and expectation which the patient has# if the substance is viewed as helpful, it can heal, but if it is viewed as harmful, it can cause negative effects, which is !nown as the nocebo effect. he basic mechanisms of  placebo effects have been investigated since /120, when it was found that the opioid antagonist naloxone could bloc! placebo pain!illers, suggesting that endogenous opioids are involved.   ecause the placebo effect is based upon expectations and conditioning, the effect disappears if the patient is told that their expectations are unrealistic, or that the placebo intervention is ineffective. A conditioned pain reduction can be totally removed when its existence is explained. 3445  &t has also been reported of subjects given placebos in a trial of anti6depressants, that 7nce the trial was over and the patients who had been given placebos were told as much, they 8uic!ly deteriorated. A placebo described as a muscle relaxant will cause muscle relaxation and if described as the opposite, muscle tension. A placebo presented as a stimulantwill have this effect on heart rhythm, and  blood pressure, but when administered as a depressant, the opposite effect. he consumption of caffeine has been reported to cause similar effects even when decaffeinated coffee is consumed, although a 9::4 study found only limited support for this. Motivation may contribute to the placebo effect. he active goals of an individual changes their somatic experience by altering the detection and interpretation of expectation6congruent symptoms, and by changing the  behavioral strategies a person pursues. Motivation may lin! to the meaning through which people experience illnessand treatment. uch meaning is derived from the culture in which they live and which informs them about the nature of illness and how it responds to  treatment. -esearch upon the placebo treatment of gastric and duodenal ulcers shows that this varies widely with society' those in ;ermany having ahigh rate placebo effect while those in ra<il a low one. Placebo effects in treating gastric ulcers is low in ra<il, higher in northern urope =>enmar!,  ?etherlands@ and extremely high in ;ermany. ut the placebo effect for hypertension is lower in ;ermany than elsewhere .  ocial observation can induce a placebo effect such when a person sees another having reduced  pain following what they believe is a pain reducing procedure. he placebo effect can wor! selectively. &f an analgesic placebo cream is applied on one hand, it will reduce pain only in that hand and not elsewhere on the body .  &f a person is given a placebo under one name, and they respond, they will respond in the same way on a later occasion to that  placebo under that name but not if under another. >ifferent areas in the higher brain have different functions. he prefrontal involvement could be related to recalling the placebo and maintaining its cognitive presence in a self6reinforcing feedbac! loop =during pain an individual recalls having ta!en the placebo and reduced pain reinforces its status as an analgesic@. he rostral anterior cingulate cortex =rA@ and its subcortical connectivity could be related to the expectation of potential pain stimuli.he brain is also involved in less studied ways upon nonanalgesic placebo effects' ã Par!inson(s disease' placebo relief is associated with the release of dopamine in the brain. ã >epression' Placebos reducing depression affect many of the same areas that are activated by antidepressants with the addition of the  prefrontal cortex ã affeine' placebo caffeinated coffee causes an increase in bilateral dopamine release in the thalamus. ã ;lucose' the expectation of an intravenous injection of glucose increases the release of dopamine in the basal ganglia of men =but not women@. ã Methylphenidate' the expectation of intravenous injection of this drug in inexperienced drug users increased the release of dopamine in the ventral cingulate gyrus and nucleus accumbens, with this effect being largest in those with no prior experience of the drug.  A negative conse8uence is that placebos can cause side6effects associated with real treatment. 7ne example of this is with those that have already ta!en an opiate, can then show respiratory depression when given it again in the form of a placebo. Placebos do not wor! upon everyone. Benry C. eecher , in a paper in /1DD suggested placebo effects occurred in about 4DE of people. Bowever, the response rate is wide, ranging from :E up to nearly everyone. &n a dental  postoperative pain model, placebo analgesia occurred in 41E. &n research upon ischemic arm pain, placebo analgesia was found in 92E. he placebo analgesia rate for cutaneous healing of left hand s!in was DFE.hough not everyone responds to a placebo, neither does everyone respond to an active drug. he percentage of patients who reported relief following  placebo =41E@ is similar to the percentage following G mg =4FE@ and F mg =D:E@ of hidden morphine. N CE! E##ECT &n its srcinal application, n%ce$% had a very specific meaning in the medical domains of  pharmacology, and nosology, and etiology. &t was a subject6oriented adjective that was used to label the harmful, unpleasant, or undesirable reactions =or responses@ that a subject manifested =thus, nocebo reactions or  nocebo responses @ as a result of administering an inert dummy drug or  placebo, where these responses had not been chemically generated, and were entirely due to the subject+s  pessimistic  belief  and expectation that the inert drug would produce harmful, injurious, unpleasant, or undesirable conse8uences.&n these cases, there is no real drug involved, but the actual harmful, unpleasant or undesirable physiological, behavioural, emotional, andHor cognitive conse8uences of the administration of the inert drug are very real.
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