New Scientist - UK (2022-05-21)

54 | New Scientist | 21 May 2022

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Placebo power

What is it exactly that

provides the healing effect

of a placebo treatment?

Tim Lewis

Narberth, Pembrokeshire, UK

The placebo effect is as mythical

as its “evil twin” the nocebo. What

appears to be an effect is just the

natural pattern of variation in

disease or non-specific symptoms.

This was illustrated in a 2001 study

published in the New England

Journal of Medicine, which

concluded that there was “little

evidence in general that placebos

have powerful clinical effects”.

Anthony Woodward

Portland, Oregon, US

The placebo response is

intriguing. A placebo is a

substance without any

known medical effects or an

interaction with a caregiver that

nevertheless improves the health

of the recipient. The placebo

response refers to all health

changes resulting from such

apparently inactive treatment.

When any treatment is given,

the overall effect is the true effect

of the intervention plus the

placebo effect, which can be large.

A 2021 meta-analysis of 186 clinical

trials found that on average, 54 per

cent of the overall treatment effect

was attributable to placebo.

The placebo effect results from

activation of opioid, cannabinoid,

and dopaminergic pathways in

the body. Dopamine is a hormone

associated with feelings of

pleasure. A placebo also sees the

release of opioids, providing an

effect similar to a morphine

injection. Indeed, the placebo

effect can actually be counteracted

by naloxone, a drug that blocks

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opioid receptors in the body.

There are even claims that

animals experience a placebo

effect. One trial reported that

86 per cent of dogs responded to

an epilepsy drug, but 79 per cent

seemed to respond just as well to

a placebo. I don’t believe a placebo

actually heals; rather it enhances

a person’s own healing potential.

David Gordon

Leeds, UK

When ill, we tend to regress

to an earlier stage of emotional

development, in need of a

parental figure who can listen

to our experience and interpret

it in a way that restores to us

some agency. This is the essence

of a good practitioner-patient

relationship. Any treatment

given in this emotional context

will tend to be more efficacious.

Furthermore, the simple act of

faith in the practitioner or the

treatment can do likewise.

Paul Rendell

Tywyn, Gwynedd, UK

I have a suggestion inspired

by an article in New Scientist

about the reasons for painful

childbirth (6 May 2015). This

is that the placebo effect is due

to a subconscious call for help.

An ancient bodily system

determines that help is

required and amplifies the

pain/symptoms to attract

the attention of others.

Once the call for help has

been answered, the amplification

can be turned off. This idea would

predict that the amplification

will only occur when help is

close enough to be attracted

by this method.

David Muir

Edinburgh, UK

Psychologists put the placebo

effect down to expectancy

theory, in which we somehow

bring about effects based on our

expectations, and/or classical

conditioning, where the effects

are brought about by automatic

conditioned responses.

Belief in the treatments helps,

but even people told that they

are receiving an inert substance

instead of efficacious medicine

still experience the placebo effect.

Placebos affect subjective

patient-reported symptoms such

as nausea and pain, but not the

causative disease itself.

Breathless birds

Do birds ever get out of breath?

Jennifer Skillen, Peter Robinson

and 21 chickens, including

cockerels Bandersnatch

and Jabberwocky

Tetbury, Gloucestershire, UK

From our experience yes, birds

do get out of breath. At least some

of our chickens do, mainly the

cockerels when they are fighting.

We have a flock of chickens

made up of American game

chickens along with some cross-

bred o-shamo and Saipan, both

Asian game chicken breeds. They

are semi-wild and most unlike the

normal tame, egg-laying chickens.

Because each clutch hatched

contains both male and female,

we have had an opportunity to

observe the behaviour of about

15 free-range cockerels over the

years, with the American game

cocks being particularly

aggressive. We usually let them

sort themselves out into the alpha

cock and his underlings – things

are tense, but not too violent.

Occasionally two equally

matched cockerels will spend a

This week’s new questions

Nippy nippers Why do little children run everywhere

instead of walking? Is it a legacy of sabre-toothed predators?

John Healey, Adelaide, South Australia

Smartosaurus What are the chances that dinosaurs would

have developed human-like abstract intelligence if they

hadn’t been wiped out? Alan Dix, Shipley, West Yorkshire, UK

Is the desire of children to run

everywhere linked to ancient

predator-evasion instincts?

“ A placebo releases

the pleasure hormone

dopamine, as well as

opioids, providing

an effect similar to a

morphine injection”