Left-handedness gene found.

Oxford University researchers have found the first gene that seems not only to increase the chances of being left-handed, but that may also slightly increase the risk of developing psychiatric disorders for example, schizophrenia. The gene, LRRTM1, seems involved in controlling the parts of the brain responsible for certain functions, for example speech and emotion1.

Published in the journal Molecular Psychiatry, the study highlights the known asymmetry of the brain, in right-handed individuals, the left side of the brain typically controlling speech and language, the right, emotions, whereas in left-handed persons, the reverse, typically the case, LRRTM1 gene, the cause, the researchers note. However, while 95% of right-handed people process language in the left hemisphere, so do 70% of left-handed people, and 50 per cent of the rest, use both hemispheres.

With about 10% of individuals left-handed, and not everyone who is left-handed has schizophrenia, clearly other factors contribute to the risk of this disease. Besides the precise role, the gene plays in schizophrenia remains a mystery. Research studies have shown other differences between left and right-handed people.

Left-handers think faster in tasks such as sports and computer games, for example, according to a 2006 Australian study2, and being left-handed gives an individual an edge in hand-to-hand combat, according to French researchers, although they tend to be more prone to certain diseases, such as allergies, auto-immune diseases, depression, drug abuse, sleeping disorders and epilepsy, and to accidents3. Indeed, some epidemiological studies have shown that they do not live as long as right-handers do, which a 2005 study published in the journal Lancet, vehemently disputed3.

Meantime, investigations into the link between brain asymmetry and schizophrenia continues, for example according to Marjorie Wallace, of the mental health charity SANE, by scientists working in its research centre in Oxford. She notes, "We desperately need research into the origins of psychosis to better understand why some people are more vulnerable than others. Then the treatment could be more targeted and carry the potential to prevent this devastating condition which affects one in 100 people worldwide."

Sources:
1. http://news.bbc.co.uk/2/hi/health/6923577.stm
2. http://news.bbc.co.uk/2/hi/health/6212972.stm
3. http://news.bbc.co.uk/2/hi/health/4242419.stm