STROKE patients are more likely to regain their cognitive functions if they speak more than one language, new research has discovered.

A study of 608 stroke victims found 40.5 per cent of those who are multilingual had normal mental functions afterwards, compared to 19.6 per cent of patients who only speak one language.

The study was carried out by a team from Edinburgh University in conjunction with the Nizam Institute of Medical Sciences in Hyderabad. The Indian city was chosen as the location for the study because its multi-cultural nature means many languages are commonly spoken, including English, Hindi and Urdu.

Of the participants, 255 only spoke one language while 353 were bilingual.

The researchers took into account other factors such as smoking, high blood pressure, diabetes and age to ensure results could not be attributed to having a healthier lifestyle.

The study, published in the American Heart Association journal Stroke and funded by the Indian Council of Medical research, found the "results support the notion of a protective role of bilingualism in the development of post-stroke cognitive impairment".

It is the first time a study has been done looking at the relationship between the number of languages spoken and a patient's cognitive outcome after stroke.

The paper states: "The percentage of patients with intact cognitive functions post-stroke was more than twice as high in bilinguals than in monolinguals.

"In contrast, patients with cognitive impairment were more common in monolinguals."

Researchers believe the study suggests the mental challenge of speaking multiple languages can boost cognitive reserve - an improved ability of the brain to cope with damaging influences such as stroke or dementia.

Co-author Thomas Bak, of the University of Edinburgh's school of philosophy, psychology and language sciences, said: "Bilingualism makes people switch from one language to another, so while they inhibit one language, they have to activate another to communicate.

"This switching offers practically constant brain training which may be a factor in helping stroke patients recover."

The researchers note that the only post-stroke trait not affected by bilingualism is aphasia, where patients mix up words.

They add that while this "might look surprising at first sight", it is actually in line with existing research which has shown that the benefit gained from bilingualism in terms of brain function does not come from wider linguistic knowledge but from the "lifelong practice of language switching".

The researchers say that the study results may not be applicable to all bilingual people because switching between languages is a daily reality for patients in Hyderabad, but this might not be the case for people who do not use their additional languages on a regular basis.

It follows previous studies which have indicated that bilingualism is associated with better cognitive function in ageing and a later onset of dementia.

Stroke is the second most important cause of cognitive disability after dementia, and the third most common cause of death in Scotland. There are also some 117,000 living in Scotland who have previously suffered a stroke.

The researchers concluded that further studies are needed to determine the exact circumstances under which bilingualism can have a positive influence on mental functions.