Introduction to the Nocebo Effect
In Roald Dahl’s 1980 classic The Twits, Quentin Blake’s illustrations depict how Mrs Twit’s unpleasant attitudes eventually altered her appearance.
“If a person has ugly thoughts,”Dahl wrote,
“it begins to show on the face.”
Helen Pilcher, a science writer, investigates this concept in her latest book, proposing that negative beliefs
“can be physically transformative.”This phenomenon, known as the nocebo effect, derives from the Latin phrase meaning “I will harm.” It occurs when a person’s negative expectations, whether conscious or subconscious, lead to actual illness.
Examining the Anatomy of the Nocebo Effect
This Book May Cause Side Effects is a comprehensive exploration of the nocebo effect. At its core, it can be described as:
“when people are warned to expect symptoms, they become more likely to experience them.”Similar to the paradoxical instruction not to think of a pink elephant, being informed that a medication might cause nausea serves as a strong psychological prompt to experience that symptom.
Analyzing 231 placebo-controlled clinical trials, Pilcher highlights that 76% of participants in experimental groups reported side effects, compared to 73% in placebo groups. She explains,
“Most of us experience funny sensations in the body at times,”adding,
“but the nocebo effect is behind becoming more aware of them, and misattributing them to a medication.”
Broader Implications Beyond Drug Side Effects
Pilcher extends the discussion of the nocebo effect to various human conditions, including ageing, “hex deaths” — deaths of individuals who believed they were cursed — and mass psychogenic illness (MPI).
History offers numerous examples of MPI, such as collective panic over shrinking genitalia in Asia, documented nearly two thousand years ago. This represents the nocebo effect on a large scale. While previously symptom contagion was geographically limited, today’s rapid global communication and social media platforms enable the nocebo effect to spread virally.
In 2014, social media is believed to have propagated a mass psychogenic illness across Colombia. At a girls’ school, children began convulsing and fainting shortly after receiving the HPV vaccine, which protects against cervical cancer. Despite health officials finding no causal link between the vaccine and symptoms, public confidence was severely undermined. HPV immunisation rates plummeted from over 90% to just 5%.
Physical Verification and Measurable Changes
The physical verification of nocebo symptoms is largely irrelevant, as subjective experiences like pain or fatigue remain inaccessible to external measurement. Nevertheless, Pilcher presents research demonstrating measurable physical changes resulting from the nocebo effect.
One notable study at Stanford involved participants who were randomly told — irrespective of their actual genetics — that they carried a gene associated with either low or high obesity risk. GLP-1, a natural hormone that induces satiety and for which synthetic analogues like Ozempic exist, was measured after meals. Participants told they had the “skinny” gene showed a significant increase in GLP-1, whereas those told they had the “fat” gene exhibited no change from baseline.
Mind-Body Interaction and Cancer Research
During an interview with a researcher who implants electrodes in the brains of cancerous mice targeting regions linked to reward processing and positive emotion, Pilcher was struck by findings that stimulating this brain area slowed cancer growth, while dampening it accelerated tumor progression. She notes,
“This is potentially huge. It’s one thing to entertain the idea that mental processes can slow the growth of cancer,”and adds,
“It’s quite another, however, to suggest that certain thoughts can make cancer worse.”
Pilcher discloses on the first page that she has a cancer diagnosis herself. Despite clarifying that stimulating a neuron in a mouse brain does not equate to positive thinking in humans, the suggestion remains provocative. There is a concern that the folk intuition supporting Mrs Twit’s fictional transformation — an intuition that aligns with emerging nocebo research — could lead to ethically troubling interpretations.
Philosophical Reflections and Practical Implications
Ultimately, This Book May Cause Side Effects addresses fundamental philosophical questions about the relationship between mind and matter and the extent to which individuals can influence their own destinies. While Pilcher avoids engaging directly with these philosophical debates, her ambitious and insightful work contributes to understanding these complex and contentious issues.
Moreover, the book offers guidance on how to mitigate the nocebo effect in everyday life. As far as side effects go, that is a beneficial one.
