A common type of prescription medicine has been linked to an almost 50 per cent higher chance of getting dementia.

Anticholinergic drugs, used to treat people with epilepsy, Parkinson's, depression and incontinence, may be linked to the brain disorder.

Researchers studied more than 280,000 people in the UK to work out how the medicines affected dementia risk.

They found the memory-robbing disorder was more common among people who were prescribed these types of drugs and suggested damage they cause to nerve cells could be to blame.

Although they said anticholinergic meds should be prescribed 'with caution' to middle-aged and older people, they also warned patients not to stop taking their medication.

But if the link was found to be a direct cause, the pills could be responsible for as many as one in 10 dementia cases, the experts added.

The Nottingham researchers said people taking anticholinergic drugs may be at a 49 per cent higher risk of developing dementia, and that the commonly prescribed pills could even account for as many as one in 10 cases of the brain-destroying disease (stock image)

Scientists at the University of Nottingham looked at decades' worth of prescribing and diagnosis data for 284,343 over-55s registered with GPs in the UK.

Nearly 59,000 of the people studied were diagnosed with dementia at some point.

Within the 11 years leading up to their dementia diagnosis, 56.6 per cent of the patients (33,253) had been prescribed anticholinergic medications.

The researchers said the odds of someone developing dementia increased by 49 per cent if they were given the drugs within 11 years of their diagnosis.

And they added the associations appeared to be stronger in people diagnosed with dementia before they were 80, suggesting the drugs played a greater role for them.

The biggest increases were seen in those who took antidepressants, anti-Parkinson's drugs, antipsychotics, antiepileptic drugs and those used to control bladder incontinence.

Professor Tom Dening said: 'This study provides further evidence that doctors should be careful when prescribing certain drugs that have anticholinergic properties.

'However, it's important that patients taking medications of this kind don't just stop them abruptly as this may be much more harmful.

'If patients have concerns, then they should discuss them with their doctor to consider the pros and cons of the treatment they are receiving.'

Professor Dening and his colleagues made it clear that their paper only pointed to a link between the prescriptions and the rate of dementia – not a direct cause.

WHAT IS DEMENTIA? Dementia is an umbrella term used to describe a range of progressive neurological disorders, that is, conditions affecting the brain. There are many different types of dementia, of which Alzheimer’s disease is the most common. Some people may have a combination of types of dementia. Regardless of which type is diagnosed, each person will experience their dementia in their own unique way. Dementia is a global concern but it is most often seen in wealthier countries, where people are likely to live into very old age. HOW MANY PEOPLE ARE AFFECTED? The Alzheimer’s Society reports there are more than 850,000 people living with dementia in the UK today, of which more than 500,000 have Alzheimer's. It is estimated that the number of people living with dementia in the UK by 2025 will rise to over 1 million. In the US, it's estimated there are 5.5 million Alzheimer's sufferers. A similar percentage rise is expected in the coming years. As a person’s age increases, so does the risk of them developing dementia. Rates of diagnosis are improving but many people with dementia are thought to still be undiagnosed. IS THERE A CURE? Currently there is no cure for dementia. But new drugs can slow down its progression and the earlier it is spotted the more effective treatments are. Source: Dementia UK Advertisement

They said people may have been given the drugs to treat early symptoms of the brain-destroying condition, but also suggested ways the meds might trigger it.

One of the main reasons, they said, was that the drugs work by relaxing muscles by blocking nerve signals, which may lead to degeneration of the crucial nerve cells in the brain.

Dementia also develops as a result of nerves in the brain breaking down – this is usually Alzheimer's disease causing a build-up which blocks electrical signals.

The scientists added that changes to the blood supply in the brain could also damage it in a way which may provoke dementia, or that the meds could trigger inflammation in the brain.

The association the researchers found was so strong, they said, that if the drugs were found to be directly causing dementia they could be responsible for 10 per cent of cases.

This would equal around 20,000 of the 209,000 new cases each year – more than are linked to high blood pressure, diabetes or inactivity, but fewer than smoking.

Dr James Pickett, head of research at the Alzheimer’s Society, said the charity had already found this link but it was hard to prove a causal relationship.

'From this information we can’t rule out whether the diseases that cause dementia might have already begun in the brains of people involved before they started taking these drugs,' he said.

'Our ongoing research at the University of East Anglia is exploring whether anticholinergic bladder drugs could increase risk by following people while they take the drug.

'This research will tell us whether these drugs can cause dementia and how they might be doing it.

'Current guidelines for doctors say that anticholinergic drugs should be avoided for frail older people because of their impact on memory and thinking, but doctors should consider these new findings for all middle aged and older people as long-term use could raise the risk of dementia.'

Other experts in the field agreed that any definitive proof of the drugs causing dementia was still elusive.

The called the study 'well-conducted' and 'robust' and said it made useful findings which added to existing work on dementia.

Professor Clive Ballard, an age-related diseases expert at the University of Exeter's Medical School, added: 'This is a very important finding with enormous and very practical implications that could improve brain health.

'We do need to consider two important caveats. Firstly, anticholinergics may impair cognition, but from this study it’s more difficult to determine whether this is a potentially reversible problem or a genuine progressive cognitive decline.

'Secondly, some of these drugs may be more likely to be prescribed to people with emerging problems such as psychiatric symptoms and urinary incontinence – which may reflect people already at increased risk of cognitive decline.

'Despite those caveats, anticholinergics are clearly damaging cognitive health – and these key implications for prescribing and clinical practice can be taken into account.'

The Nottingham team's research was published in the journal JAMA Internal Medicine.