Can acupuncture offer relief from pain – and if so how? In a new episode of the BBC’s Trust Me I’m A Doctor  on Wednesday next week, York acupuncturist Hugh MacPherson
and a team of scientists from the York Neuroimaging Centre look at evidence for the way acupuncture may affect pain centres in the brain. STEPHEN LEWIS reports.

MICK O'Neill prides himself on being fairly fit and healthy for 61. He has run a few 10K races. "And I'm quite an active person," he says. That is, until he gets a bad back.

Mick is the managing director of a tile company with branches across Yorkshire. It's a business that involves a lot of heavy lifting – and he often suffers from lower back pain.

It can be excruciating. "I can't even walk with it."

When that pain strikes, Mick doesn't go to see his GP. Instead, he usually heads for the York Clinic on Tadcaster Road and a session with acupuncturist Hugh MacPherson.

Acupuncture just seems to work, he says. "It is very relaxing. The needle doesn't hurt when it goes in. When the acupuncturist turns it, it can hit a nerve and you jump – but that's when it has hit the place it wants to get to.

"You drift off, wake up three-quarters of an hour later, and your back will still ache for a while, but within a day or two maybe, it has cleared up."

He doesn't really know how it works, but neither does he much care, he says. He's been going to York Clinic for ten years or more whenever the pain flares up. A couple of sessions will usually clear it. "I'm a great believer that if it works, that's fine for me," he says.

Traditional Chinese medicine talks about a natural energy or 'chi' which flows in every living being along channels or meridians in the body. Every meridian influences an organ, and there are different meridians for the heart, liver, stomach and so on.

Acupuncture points related to these organs are found along the meridian. And according to traditional theory, when an acupuncture needle is inserted at an acupuncture point and manipulated, it affects the areas of the body that the meridian connects to.

Such explanations don't satisfy hard-nosed western scientists and medical practitioners, however.

If they're to accept acupuncture, they want proper clinical evidence that it works.

Step forward Hugh MacPherson. He's been practising acupuncture for more than 30 years, the last 20 of them at the York Clinic on Tadcaster Road.

But before he became an acupuncturist, Hugh left his home town of Edinburgh to do a Ph.D in fluid mechanics at the University of New South Wales in Australia – which means officially he's Dr Hugh MacPherson.

He decided against an academic career at the time. But after many years as an acupuncturist, he became interested in doing research on how effective it is for different conditions, and also on exactly how the technique works.

At first it was just a hobby, but several years ago he started doing some post-doctoral research work at the University of York. Now, as well as being an acupuncturist one day a week, he's also a a senior research fellow in the university's Department of Health Sciences.

Over the last few years, he has collaborated with staff at the Hull York Medical School and at the University of York's York Neuroimaging Centre on a string of research projects, with papers published in prestigious academic journals.

One thing he's interested in looking at, he says, is what happens in the brain when someone undergoes acupuncture. If we could understand that, might it help explain how acupuncture works?

So he set up an experiment with colleagues at the York Neuroimaging Centre. They took 17 healthy subjects, and Hugh gave them acupuncture while they lay in a magnetic resonance imaging (MRI) scanner at the centre. Their brains were scanned as the acupuncture was performed in order to look for evidence of changes in areas of the brain associated with pain.

"Acupuncture has a good reputation for pain," says Hugh. "We were looking at how the brain processes the signals from acupuncture and what we can learn about how acupuncture may modify the processing of pain."

What they found was fascinating. People experience different sensations when an acupuncture needle is inserted. One sensation is what acupuncturists call 'deqi'. This is a slight heaviness or numbness, a soreness or ache similar to a slight cramp.

What the York trial found was that, among the subjects who reported experiencing deqi, areas of the brain associated with pain were 'deactivated' during acupuncture.

The MRI scanner was measuring blood oxygen levels in the brain - and what seemed to be happening was that the acupuncture was decreasing blood flow and therefore reducing neuronal activity in those areas of the brain.

"It is clear that acupuncture is having an effect on parts of the brain that pain is processed in, and that may explain how it works," says Hugh.

Research neuroscientist Dr Aziz Asghar of Hull York Medical School, who was also involved in the study, stops short of saying we now have an explanation of how acupuncture works to reduce pain.

All the study shows was that acupuncture can cause a decrease in blood flow in parts of the brain associated with processing pain, he says.

"One interpretation of that is that perhaps this is how acupuncture might cause reductions in the sensations of pain," he says.

There is a great deal of work to be done yet however, he points out. The results might be down to a placebo effect.

A placebo is something that seems to be a "real" medical treatment, but isn't. It might be a tablet with no active ingredients that a patient thinks may contain medicine. Sometimes patients respond to placebos – the belief that they are being treated in itself makes them feel better.

Is this what may be happening with acupuncture? Hugh insists that there is now a significant body of evidence showing that real acupuncture is more effective at dealing with patients' symptoms than 'sham' (or placebo) acupuncture in which patients believe they are being given acupuncture but in fact are not.

"The latest research evidence from high quality clinical trials shows that acupuncture is significantly better than placebo," he says.

The neuroimaging study was not set up to address the placebo question. But it does provide a possible suggestion for how acupuncture may reduce pain. And it was sufficiently interesting to attract the attention of a team from the BBC programme, Trust Me I'm A Doctor.

In May this year, Hugh, Aziz and their colleagues repeated their experiment, this time using just a single subject: Trust Me I'm A Doctor presenter Dr Saleyha Ashan.

She lay in the MRI scanner at York while Hugh gave her acupuncture on her and simultaneously her brain was scanned.

You'll be able to see what happened for yourselves by tuning in to the BBC next Wednesday, when the first episode of the new series of Trust Me I'm A doctor is screened at 8pm.

Hugh will only say that after the experiment, the York team showed Dr Ashan her brain scans. "And I have to say she was quite surprised," he says.

• The first episode of the new series of Trust Me I'm A Doctor airs on BBC2 at 8pm on Wednesday. As well as Dr Saleyha Ashan's piece looking at whether acupuncture is effective for pain relief, medical journalist Michael Mosley explores whether getting a bit more sun on our skin could actually be good for us, and the results of an experiment looking at whether changing the way we prepare starchy foods like potatoes and pasta could reduce the number of calories the food contains are revealed.

• Hugh MacPherson works at the York Clinic, Tadcaster Road, telephone 01904 709688.