Left-handers more at risk of mental illness (Telegraph)

[Joe Duffy]

[top] Left-handers more at risk of mental illness

By Laura Clout
Last Updated: 1:49am BST 31/07/2007


Left-handed people may have an increased risk of developing schizophrenia, scientists have found.

An international group of scientists, led by a team at Oxford University, have identified a gene that
seems to increase the chance of being left-handed.

The researchers said that the same gene - called LRRTM1 - may slightly increase the risk of
developing the brain disorder.

Schizophrenia is a highly complex condition that results in impaired perception and thought, it affects
around one in every 100 people.

Although little is known about the gene, the Oxford team suspects it modifies the development of
asymmetry in the human brain.

In humans, the left side of the brain usually controls speech and language, and the right side controls
emotion. In left-handers, however, this pattern is often reversed. In a similar way, people with
schizophrenia often have unusual patterns of brain asymmetry.

The leader of the study, Dr Clyde Francks of the Wellcome Trust Centre for Human Genetics, said:
"People really should not be concerned by this result. There are many factors which make individuals
more likely to develop schizophrenia and the vast majority of left-handers will never develop a problem.
We don't yet know the precise role of this gene."

There is also evidence that asymmetry of the brain was an important feature during human evolution.
Apes' brains are more symmetrical than humans' and they do not show a preference for using either
the right or left hand.

Dr Francks added: "We hope this study's findings will help us to understand the development of
asymmetry in the brain.

"Asymmetry is a fundamental feature of the human brain that is disrupted in many psychiatric conditions."

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