PEOPLE at risk of dementia will be able to take a pill in their 20s and 30s to prevent it, according to a leading scientist and Scotland could be the country responsible for that breakthrough.

Professor Craig Ritchie said he is "very hopeful" that current research focussed on prevention of the disease that affects an estimated 90,000 Scots will lead to treatments that halt the changes in the brain that lead to dementia.

It is now known that around 30% of dementias are preventable.

Professor Richie, who leads the Scottish Dementia Research Consortium, said a lot of the drugs involved in recent trials had failed because "they haven't gone in early enough"

Scotland is recognised globally for studies involving significant numbers of healthy volunteers and those with a family history of dementia, who have not yet developed symptoms of the disease. The aim is for the country to have the largest population of people signed up to dementia research.

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Future treatments could also work in a similar way to the drug that prevents HIV from developing into AIDS.

He said: "A lot of the changes that lead to dementia in later life have their origins in mid-life.

"Clearly if we can identify those early change in the brain then those are the people for which risk factor modification might slow down the progression and/or some sort of pharmacological intervention. That's the goal and that's what we are working towards.

"I always say 40s but you might say 20s or 30s.

"That's not too much of a stretch for people who work in say heart disease or cancer or diabetes.

"Dementia is inevitable if you pick it up at the end stage. You can't expect to cure cancer in someone where it is spread all over their body. That's the same with Alzheimer's disease.

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"If we can pick it up early enough then we should theoretically be able to intervene and cure the condition rather than in the advanced stages.

"We are gathering vast amount of data before dementia develops and globally we are recognised as one of the best in the world for that type of research.

"We know that the incidence rate of dementia in Europe and the US is going down.

"The number of people in each age band who develop dementia is reducing because of better cardiovascular health, less smoking and I often say look what's happened inadvertently. Imagine what could happen if we really target brain health. Then we would see a really tangible reduction in incidence.

"The flip side of course is the incidence of old age is going up so the total number of people with dementia is increasing.

"We have been really challenged over recent years in developing drugs to help people with the memory symptoms. There has been a focus in the pharmaceutical industry for drugs that we can use really early to prevent people getting dementia but there are reasons why those have not been successful.

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"There are headlines almost on a daily basis about another drug that has failed. My own person view is that, that is because we haven't been able to go in early enough with treatments, even with people are just about to be given a dementia diagnosis. So it's maybe just a wee bit too late.

"So the question is how do we identify people really, really early."

There are four main drugs available that tackle the symptoms of dementia, which are "good drugs" according to Alzheimer Scotland but have been available for around 20 years.

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However Professor Ritchie, who is Professor of Ageing at he University of Edinburgh, says we shouldn't assume that the treatment of dementia is synonymous with a pharmacological response. Research has shown that as well as taking exercise, not smoking and maintaining a healthy diet, brain health is crucial for reducing the incidence of dementia and delaying progression.

He said: "We know if you have a good education in childhood that reduces your risk of dementia in later life.

"Lifelong learning is really important. We know that depression in mid life is a risk factor. Social isolation is a major risk factor for dementia so finding ways to ensure elderly don't become isolated is incredibly important.

"If you get all those three things right the need for drugs to reduce dementia decreases.

"We need to be aware that people with dementia can benefit massively from non-pharmacological interventions."

Around £160million of publicly funded research is currently targeted towards dementia and while there is a disparity with the amount spent on cancer and cardiovascular research, Professor Ritchie says it is still a "vast amount of money."

The charity says cohort studies are helping make Scotland more attractive to the research companies who have "hundreds of millions" to spend.

He said: "Of course you are going to want more money but number one the gap is closing, number two the way we spend that money is really important.

"If the research projects are coordinated you are going to gain a far greater amount of knowledge and that's really important for a small country."