How Does the Placebo Effect Work? Can It Explain the Success of Homeopathy? 

Homeopathy and other forms of alternative medicine would appear to be the equivalent of taking a sugar pill. Does that mean they don’t work?
Image of a brain made of pills
A group of scientists led by Ted Kaptchuk is focused on studying this effect through interdisciplinary research that combines basic science, clinical science, and social science. (Photo: Getty Images)

In the world of medicine, few topics are as divisive as homeopathy. Many oppose it, while others fight tooth and nail to defend it. For some, it’s no more than an example of the placebo effect

“One reason it doesn’t get accepted is that we don’t have a good biomedical explanation for how it works,” says Michelle Dossett, integrative medicine specialist and researcher at the University of California, in an interview with TecScience

Homeopathy is an alternative medicine created in Germany over 200 years ago, centered around the idea that the body can heal itself

To create remedies –tablets, drops, creams, or gels– homeopaths prepare a mixture of substances with active ingredients, such as plants, minerals, or animal venom, and add them to water or alcohol to enhance their effects. 

The substances are extremely diluted in these remedies, as another of their beliefs is that the lower the dose, the greater the effect. This is one of the main reasons conventional medicine opposes it. 

How could they possibly work if they contain undetectable quantities of these substances? 

However, despite many arguments against them, a significant part of the population around the world frequently turns to homeopaths to treat their illnesses. 

For example, my grandmother calls hers “Merlin” because she says he’s “like a wizard” who makes her feel better whenever she has a cold or a stomach ache. 

Although science resorts to the placebo effect to explain that this alternative medicine leads to many patients reporting an improvement in their symptoms and mood, this doesn’t mean it doesn’t work. 

“Saying homeopathy is just a placebo is saying it’s a treatment that’s going to help people,” says Kathryn Hall, a researcher at Harvard Medical School, in an interview with TecScience

What is the Placebo Effect? More than a Trick or Positive Thinking 

The placebo effect occurs when an inert treatment (like a sugar pill, an injection without an active substance, or a simulated surgery) improves the symptoms of an illness. 

“All of these sham treatments can have beneficial effects, sometimes even as powerful as the active treatment,” says Hall. 

She and Dossett form part of a group of scientists led by Ted Kaptchuk that’s focused on studying the placebo effect through interdisciplinary research combining basic science, clinical science, and social science. 

Over the years, these researchers have demonstrated that placebos are more than tricks or positive thinking. Instead, they result from our mind and body’s capacity to react to adverse situations like illness. 

“It takes advantage of our inherent biology and innate capacity to feel better,” explains Dossett. 

The placebo effect is not a cure, as it cannot eliminate bacteria or reduce the size of a tumor. What it can do is minimize symptoms that are modulated by the brain, such as the perception of pain. 

Pain is processed by a specific area of the brain called the prefrontal cortex, and it has been observed that when a placebo is administered, it can override the signals of discomfort.

This is probably why my grandmother feels better when the homeopath gives her pills to take away the headache caused by a cold. 

Neurobiological Mechanisms of the Placebo Effect 

Although it’s unclear how it works, the evidence suggests that the placebo effect involves neurobiological processes such as releasing neurotransmitters associated with wellbeing, including dopamine. 

It has also been found to activate our endogenous opioid system, a group of molecules similar to opiates such as morphine, which are fabricated and released by the brain, helping us to stop feeling pain. 

Moreover, it can increase activity in brain regions associated with mood, reward, emotional reactions, and cognitive capacities such as complex thinking and self-perception. 

For a long time, the placebo effect was considered a failure as inert substances (or placebos) are used in clinical trials to prove that a medication or treatment really works. 

Generally, this includes dividing people into one group that receives the medication or treatment while the other gets the placebo. “The standard goal is for the effect of the medicine or treatment to be statistically higher,” explains Hall. 

The narrative around this phenomenon has begun to change, recognizing that patients responding to the placebo is not necessarily a sign that the treatment doesn’t work. 

Instead, it means there are non-pharmacological mechanisms that could be acting to help patients improve. 

“I think many physicians are aware of the placebo effect, but few recognize its power,” says Dossett. 

Warmth and Empathy: Key Aspects of the Placebo Effect 

So far, the placebo effect has been demonstrated to be effective at treating symptoms such as pain, discomfort, insomnia, anxiety, and stress, as well as the fatigue and nausea associated with cancer. 

However, beyond releasing our mind’s power to heal, the evidence suggests that it also has to do with the whole experience of seeking treatment. 

This begins when we realize that we don’t feel well, which leads us to call the doctor, go to the doctor’s office, answer a series of questions, and occasionally undergo certain tests to receive a diagnosis and treatment. 

“There is so much stuff you’re going through that obviously affects you,” says Hall. Your brain is a prediction machine. Even before receiving treatment, it knows you’ll get something that will make you feel better.” 

The interaction with the doctor seems to be a particularly key factor in a patient’s likelihood of recovery. 

In 2015, Dossett and her team studied the effect of a supplement to treat reflux, analyzing whether its efficacy changed depending on the type of consultation. 

One group received a standard examination before receiving the supplement, while the other had an expanded visit with a more extensive set of questions. 

They found that although the supplement had no effect on reflux symptoms, the patients who had the extended consultation were more likely to report an improvement of 50% or more in the severity of their symptoms. 

Furthermore, when they analyzed the videos of the interaction between patient and doctor, they found that patients seemed more satisfied at the end of the extended consultation. 

“Having doctors and patients smiling at the end of the visit was highly predictive of the improvement of their symptoms two weeks later,” explains Dossett. 

Kaptchuk’s group and other researchers have extensively studied the therapeutic effect of patient-doctor interaction, suggesting that the warmth and empathy patients receive affect how they will respond to treatment. 

This could explain why people, including my grandmother, answer positively to alternative medicines such as homeopathy and acupuncture

During consultations for these types of treatments, doctors tend to ask questions about a holistic view of the patient, including their mood, recent experiences, life history, and events that could affect them. 

Genetic Factors of the Placebo Effect 

Recently, Dossett and her group sought to extend the results of their research, measuring whether going to a consultation without receiving treatment could improve reflux symptoms. 

They found that although patients with an extended visit were more likely to feel better than those who received a traditional examination, this difference wasn’t statistically significant. 

“There’s probably something with receiving something as treatment, even though it’s inert, that has a therapeutic effect based on expectation,” says Dossett. 

It would seem that patients also need to receive something for the placebo effect to work, whether it be an ointment, a pill, or an injection. Even receiving a placebo knowing what it is appears to work

Hall’s group also found that the likelihood of people responding to the placebo effect could be associated with genetic variants. 

In 2017, they published a study in which they observed irritable bowel syndrome, which tends to have a high response to placebos in clinical trials. 

When they analyzed the genome of patients who responded to the placebo and those who didn’t, they found a gene that produces an enzyme -called COMT- that breaks down dopamine in the brain. 

Some people have a variant of the gene that results in a debilitated version of the enzyme, which results in them having more dopamine available. “Those with the weaker version were more likely to respond to the placebo,” explains Hall. 

Placebo Effect to Improve Treatment 

Taken as a whole, these studies suggest that the placebo effect involves the subjective and subconscious experience of a symptom or illness. Behind this lie many biological mechanisms that are now becoming clearer. 

As to whether this phenomenon explains why homeopathy can help people feel better, Dossett emphasizes that there is mixed evidence, with some studies demonstrating it can have an impact beyond it.

However, just like conventional medicine, the homeopathic phenomena surely does involve the placebo effect. “The clinical encounter, the intake of a homeopathic remedy, the questions that a homeopath asks have engendered huge effects on patients,” says the expert. 

According to these scientists, all this information means that there are non-pharmaceutical ways to improve the way we treat disease.  

“The surprising piece is how much we ignore all of this information and put the focus on the chemical substance,” says Hall. 

We should clarify that this doesn’t mean alternatives are effective for every ailment. Some diseases -such as cancer or AIDS- require conventional medicine for treatment or a cure. 

When used safely, recognizing the power of the placebo effect or the potential of alternative medicine doesn’t undermine conventional medicine. Instead, it suggests that it can be complemented. 

In the end, the goal of every health professional is to maximize patients’ response to treatment. 

“If using a placebo helps them deal with pain or nausea, or improving the nature of the interaction can increase their likelihood of improvement, why wouldn’t you?” asks Dossett. 

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Inés Gutiérrez Jaber