SMOKING can effect a vital part of the brain important for thinking skills, new research has shown.

Scientists at the University of Edinburgh found smokers tend to have a thinner outer layer of the brain - known as the cortex - compared to non-smokers, leading to problems later in life.

Although the cortex grows thinner with normal ageing, the study found that smoking appears to accelerate the thinning process.

This can lead to problems in cognitive areas such as memory, language and perception.

Anti-smoking charity ASH Scotland said the impact on the brain was another good reason for smokers to stop as the findings showed people who give up smoking may reduce the thinning.

ASH Scotland chief executive Sheila Duffy said: "This study suggests healthier brain function could be another of the many health benefits of quitting smoking.

"Tobacco smoke is toxic and previous research has shown smoking can be a risk factor for dementia, while mental decline in older age may be speeded up by tobacco use.

"Along with that, tobacco use and exposure to second-hand smoke are linked to cardiovascular disease, diabetes and stroke - underlying risk factors for conditions that can affect the brain."

The study, conducted in partnership with the Montreal Neurological Institute at McGill University in Canada, gathered health data and analysed MRI scans of 244 males and 260 females with an average age of 73, around half of whom were former or current smokers.

They analysed how a person's smoking habit was linked with the thickness of the brain's cortex using detailed MRI brain scans, careful image analysis and statistical models.

Professor Ian Deary, Director of the Centre for Cognitive Ageing and Cognitive Epidemiology at the University of Edinburgh, who led the research project, said: "It is important to know what is associated with brain health in older age.

"From these data we have found a small link between smoking and having thinner brain grey matter in some regions.

"There are findings in our study that could suggest that stopping smoking might allow the brain's cortex to recover some of its thickness, though we need further studies conducted with repeat measures to test that idea."

The group tested were part of the Lothian Birth Cohort 1936, a group of individuals who were born in 1936 and took part in the Scottish Mental Survey of 1947.

Researchers found that, regardless of the amount smoked in their lifetime, those who had given up for the longest time had a thicker cortex.

Professor Joanna Wardlaw, Director of the Brain Research Imaging Centre at the University of Edinburgh, said: "The effects of smoking on the lungs and heart are well known, but our study shows that there are important effects on the brain as well, another good reason for not smoking."

The research is published in the journal Molecular Psychiatry and is part of a larger project called the Disconnected Mind that is supported by funding from Age UK.

Additional support was received from the Medical Research Council and the Biotechnology and Biological Sciences Research Council.

Professor James Goodwin, Head of Research at Age UK, said: "Understanding how and why our thinking skills change with age is a major current health challenge.

"This work helps us to understand how smoking affects the brain in later life. The more we can find out about what influences our thinking skills as we age, the better the advice that we can give people on protecting their cognitive health."