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.
