Despite its influence in medical research and practice, little is known about how the placebo effect can produce results or symptoms simply by prompting the mind. The power of patients’ expectations represents a gap in current medical knowledge regarding the relationship between mind and body.

1. Curing depression by believing in antidepressants

Antidepressant medications are based offof the ‘chemical-imbalance’ theory – that depression stems from a deficiency of certain neurotransmitters – and that artificially replacing these neurotransmitters will lift depression. However, a study by The American Psychological Assocciation found that 80% of the effect of antidepressants could be attributed to the placebo effect.

“If antidepressants correct a chemical imbalance that underlies depression, all or most depressed people should get better after taking them. That they do not suggests that we have only barely begun to understand the disorder at a molecular level. As a result, we must consider other, nonchemical leads,” wrote Hal Arkowitz, associate professor of psychology at the University of Arizona, and Scott O. Lilienfeld, psychology professor at Emory University in the Scientific American Mind.

Many other studies have also demonstrated the ineffectiveness of antidepressants, and revealed that pharmaceutical companies were not disclosing all information regarding their drug trials.

2. You can think yourself drunk

An experiment conducted by two psychologists at Victoria University in New Zealand found that participants who were led to believe they were drinking vodka had impaired judgement and did worse on simple tests – even though their cups were only filled with tonic water. Maryanne Garry, one of the researchers, says the research has given new insights into how human memory works and how both social and non-social influences can affect a person's recall of events.

"In fact, the 'vodka and tonic' students acted drunk, some even showing physical signs of intoxication," she said. "When students were told the true nature of the experiment at the completion of the study, many were amazed that they had only received plain tonic, insisting that they had felt drunk at the time. It showed that even thinking you’ve been drinking affects your behaviour.”

3. Location, location, location: Geography matters

Patient expectations have a major mechanism in placebo effects, and a person’s expectations, fear and trust is moulded strongly by their cultural surroundings. Placebo studies and their results vary widely from country to country. For example, a trial of placebo ulcer medication revealed that Germans had a strong placebo effect while Brazilians showed little to none. On the other hand, trials of antihypertensive drugs found a weaker placebo effect in Germany than in other countries.

Furthermore, expectations toward medical procedures change its effectiveness – Americans react more positively toward placebo injections than pills, the converse of which is seen in Europeans. These variations show that individual experiences mould the placebo effect, and that similar conditions hold different weights in different cultures.

4. Beyond brand recognition – the power of pill colours

Apart from brand recognition and preventing mix-ups during production or packaging, the colour of medications can change its effectiveness – with the help of the placebo effect.

“The shape and colour of a placebo pill may endow it with a greater effect. For example, a red and blue striped placebo caplet looks more impressive and may project an aura of being more effective than a plain white tablet,” said Henry A. Nasrallah, editor-in-chief of Current Psychiatry.

Pharmaceutical companies are aware that people associate drug colours with specific effects, and use this knowledge to their advantage when developing products. For example, red pills cause patients to be more alert, yellows make the most effective antidepressants and white soothes pain. Brighter colours and embossed brand names play a larger role in treatment than patients are aware of.

5. Fake surgeries “work”

The New England Journal of Medicine (NEJM) published a trial in 2013 where 146 patients were randomly assigned to have either arthroscopic partial meniscectomy or a sham surgery. Patients who had undergone partial meniscectomy did no better than subjects who received a fake surgery.

Another NEJM trial also demonstrated how patients who were treated with vertebroplasty showed similar improvements to patients who merely received simulated procedures. These studies of extreme placebo raise questions about practicality and ethical issues, but are nevertheless a testament to the power of mind and body.

6. Effect is more powerful over time

First noted in the late 1700s, the placebo effect has gained greater recognition over the years, and the magnitude of the effect has grown with it. A study conducted by researchers at McGill University found that the placebo effect is getting stronger with time. The researchers analysed clinical drug trials conducted worldwide between 1990 and 2013, and found that pain inhibition experienced by patients taking placebos increased steadily over this period. This phenomenon can be attributed to many factors, namely advancement in the medical field and the increasing faith in medicinal procedures, but also to the fact trials are now being run longer and involve more participants than before. MIMS

Read more:
Placebo or nocebo: The importance of doctor-patient conversations
When are placebos no longer placebos?
Why do placebos work?
Is acupuncture a medical sham or a genuine treatment?

Sources:
http://listverse.com/2013/02/16/10-crazy-facts-about-the-placebo-effect/
http://www.collective-evolution.com/2017/01/20/new-facts-about-depression-and-adhd-that-your-doctor-probably-doesnt-even-know-about/
https://www.scientificamerican.com/article/is-depression-just-bad-chemistry/
http://news.bbc.co.uk/2/hi/health/3035442.stm
https://opinionator.blogs.nytimes.com/2010/05/03/enhancing-the-placebo/?_r=0
http://www.theatlantic.com/health/archive/2014/10/the-power-of-drug-color/381156/
http://www.huffingtonpost.com/david-h-newman-md/placebo-surgery_b_4545071.html
http://www.sciencealert.com/the-placebo-effect-is-somehow-getting-even-better-at-fooling-patients-study-finds