Posts tagged placebo effect
Articles and news from the latest research reports.
Placebo and the Brain: How Does it Work?
Placebo, the positive effect of a drug that lacks any beneficial ingredients, has been researched for centuries but remain a mystery for psychologists and neuroscientists alike. Although there is now a considerable amount of amassed knowledge of how placebo can be induced, through which mechanisms it works, and which individuals are susceptible to the effect, the explicit answer to why and how our brains have the ability to ‘cure’ themselves under certain circumstances is yet to be found. Having dived into the literature on the phenomenon, a picture has emerged in which one of the brain’s greatest tricks can be better understood and the fascinating implications it has for how we look at the body-mind distinction.
What is termed a placebo is usually defined in research trying to pin down its nature as the treatment that results in a change in symptom or condition that differs from the natural course of the specific disease. Placebo effects have been shown for mainly relief of pain, but also in studies of depression, parkinson’s, and anxiety. While the sugar pill is still in use, we now know that there are a two factors that are crucial for a placebo effect to occur. These are the level of expectancy and desire to get better/not get worse that the patient feels and both are in turn sensitive to a host of psychosocial variables such as their faith in medical staff, the emotional tone of the physician-patient interaction (whether it is optimistic or pessimistic for example), memories of past experiences with the effects of medicine, and so on.
While some individuals show reliable placebo effects, others do not and the underlying causes have recently been suggested to be tied to our individual genetic makeup. Researchers from the Harvard Program for Placebo Studies found that the magnitude of the placebo effect was tied to genes coding for an anzyme that regulates the levels of dopamine in various regions of the brain. Dopamine plays a key role in processing of reward, pain, memory, and learning, all areas in which the placebo effect has been demonstrated. The study, led by Kathryn Hall, concluded that persons whose genes promote an upregulation of the levels of dopamine in the brain also exhibit the greatest placebo effects. In other studies examining release of another group of transmitters called opioids, which regulate the activity in areas that code for pain, higher amounts of opioids were matched to the size of the placebo effect found.
As for where the effect originates, research using brain imaging have found that when a real drug is compared to the effects of a placebo very similar areas show activation but some areas, such as the lateral and central prefrontal cortex, show a greater response in the placebo condition. This part of the brain is often described as overseeing and exerting control over other processing in the brain and act as a connecting point for different streams of information that build up our expectations and desires.
So, how can this knowledge about the placebo effect influence the way doctors discuss, promote, and administer their own treatments? Surely, if we know that an encouraging prognosis given together with a sugar pill can be as effective in some cases as a pharmacological product but without the side- effects, we should be using that. However, having doctors treat their patients through deception leads to obvious problems such as public mistrust in the profession. A finding from the scientists at the very same Harvard program for placebo studies might have the answer. They namely demonstrated that the placebo effect remained when participants were told explicitly that the treatment they were given was in effect useless.
The placebo effect goes beyond humans
Rats and humans have at least one thing in common: They both react the same way to a placebo, according to a new University of Florida study.
“That was the big finding — that the animals that expected pain relief actually got pain relief when you gave them an inert substance,” said co-author John Neubert, a pain specialist and an associate professor with the UF College of Dentistry department of orthodontics. “It helps validate our model that what we do in the rats, we believe, is a good representation of what’s being seen in humans.”
The investigation of placebo effects might lead to the identification of new therapeutic targets in the brain and of novel treatment strategies for a variety of health conditions.
A placebo response is a response seemingly to a treatment that has not actually been administered. For this study researchers looked at placebo responses in reference to pain and pain relief by evaluating how an animal responds when it “thinks” it’s getting a pain reliever.
UF researchers conditioned rats to expect morphine or salt water by giving injections of one or the other for two sessions. Then during the third session, researchers gave both groups the saline injection. About 30 to 40 percent of the group that had previously received morphine acted as if they had received morphine again and showed pain relief.
“What that means is we can then go ahead and do more mechanistic studies and do pharmacological studies targeting different receptors,” he said. “We could do different procedures and try to apply that knowledge into what we think is going on in humans.”
The two-year study published in the journal PAIN in October was the result of collaboration between Neubert and Niall Murphy, an addiction specialist and adjunct associate professor at the University of California Los Angeles. The two decided to look at placebo responses because that deals with pathways and mechanisms that relate to pain, reward and addiction.
When the going gets tough, the tough get… more relief from a placebo?
Are you good at coping when life gets tough? Do people call you a straight-shooter? Will you help others without expecting anything in return?
Those personality traits might do more than help you win a popularity contest. According to new University of Michigan-led neuroscience research, those qualities also might make you more likely to get pain relief from a placebo – a fake medicine.
And, the researchers show, it’s not just your mind telling you the sham drug is working or not. Your brain’s own natural painkiller chemicals may actually respond to the pain differently depending on your personality.
If you’re more of an angry, hostile type, they find, a placebo won’t do much for you.
For the first time, the new findings link specific, established personality traits with an individual’s susceptibility to the placebo effect from a sham medicine for pain. The researchers showed a significant link between certain personality traits and how much relief people said they felt when given the placebo – as well as the level of a specific chemical that their brains released.
The work, published online in the journal Neuropsychopharmacology, was done by a team of U-M Medical School researchers and their colleagues at the University of North Carolina and University of Maryland.
Placebo’s Effect May Depend on Your Genes
Your response to placebos, or dummy medicine, may depend on your genes, according to a new study.
People with a gene variant that codes for higher levels of the brain chemical dopamine respond better to placebos than those with the low-dopamine version.
The findings, reported online Oct. 23 in the journal PLoS One, could help researchers design medical studies that distinguish the placebo response from the underlying effect of a medicine — the real aim of drug trials.
New insights into placebo effect
Mathematical models developed by scientists at the University of Bristol are providing new insights into why the placebo effect exists and when it should occur. Their research is published in the journal of Evolution and Human Behaviour.
A placebo – such as a sugar pill – is a treatment which is not effective through its direct action on the body but works because of its effect on the patient’s beliefs. But if individuals are capable of recovering without external aid, why do they rely on an external cue? In other words, why have individuals not evolved the ability to get better immediately on their own?
Members of the Modelling Animal Decisions group in the University of Bristol’s School of Biological Sciences built mathematical models of the placebo effect which examine the trade-off between the costs and benefits of an immune response when faced with a health problem.
The work is based on an idea proposed by the theoretical psychologist Professor Nicholas Humphrey. He proposed that, as it can be beneficial to hold the immune system back from full operation due to uncertainties about the state of the world (such as the possibility of starvation), cues which indicate a change can therefore lead to an altered level of immune response.
The models take this argument even further and demonstrate that the placebo effect is modulated by the patient’s expectations. Previous studies measuring brain activity using functional magnetic resonance imaging (fMRI) provide experimental evidence which support the models, by showing correlations between the placebo effect and regions of the brain associated with expectation.
The models show why changes to the perceived cost of getting well, the value of being well or external environmental factors can induce the placebo effect.
Dr Pete Trimmer, lead author of the work, said: “The placebo effect comes down to expectations about when to take action. Waiting for a useless pill before taking action is not optimal. But the general responsiveness to cues is adaptive, so it is logical for evolved organisms to display the placebo effect.”
The models indicate that under stress it can be better for the immune system to work less effectively. However, the most important finding of the research is that the particular type of belief in the treatment can lead to positive or negative effects. The belief that a treatment will cure, without any need for the immune system to do anything, could have deleterious effects on the patient’s health.
Now that a theoretical approach has laid the foundations of understanding the placebo effect, future empirical work may provide insights as to how the placebo effect can be invoked and controlled in a clinical environment. The Bristol study clearly shows that the focus of future placebo studies should be shifted to the type of belief patients have about their treatment rather than just whether a treatment is helpful or harmful. A better understanding of the placebo effect may change the code of practice for health practitioners and save human lives.
Source: University of Bristol
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