What A Man's Hands Say About His Risk For Schizophrenia

Could a simple finger test screen for schizophrenia?

Maybe so, at least in men. New research suggests that the ratio of the length of a guy's index finger to his ring finger may predict his risk for the devastating mental disorder.

For their research, which was conducted between 2012 and 2013, scientists in Turkey measured the fingers of 103 male patients with schizophrenia and those of 100 healthy men. Then they calculated each participant's "digit ratio" -- the length of the index finger compared to the length of the ring finger -- for each hand.

What did the researchers find? Compared to the healthy men, men with schizophrenia had a digit ratio that was significantly higher for the right hand. In other words, men with schizophrenia tended to have comparatively longer right index fingers and shorter right ring fingers. On the left hand, men with schizophrenia had significantly lower digit ratios than healthy men.

It's not the first time researchers have linked digit ratios to health and behavior. Previous studies have identified links between digit ratio and sexual orientation, academic performance, physical aggression, and heart disease.

What explains these peculiar links? Previous research suggests that just as exposure to abnormally high levels of testosterone and other hormones in the womb can affect brain development in a way that raises the risk for schizophrenia and other mental disorders, it also affects the development of fingers.

Since the study involved only men, it reveals nothing about a possible link between digit ratios and schizophrenia in women. And the researchers say more research is needed to corroborate their finding in men.

A paper describing the research was published online Mar. 16 in the journal Clinical Anatomy.