You've probably heard about how looking at the length of a man’s fingers can identify the extent to which he’s likely to be unfaithful to his partner. Now, new research suggests that the ratio between the lengths of a man’s index finger and ring finger can give clues to his risk of schizophrenia — a severe mental disorder that affects some 24 million people around the world.
The study, published in Clinical Anatomy, was completed by researchers in Turkey who measured the finger lengths of 103 male patients with schizophrenia, then compared them to the finger lengths of 100 healthy men. Each participant’s “digit ratio” was calculated, meaning the scientists looked at how the length of their index fingers matched up to that of their ring fingers. The researchers found that men with schizophrenia had a higher digit ratio for the right hand than men without the disorder. In other words, schizophrenic men were more likely to have longer right index fingers and shorter ring fingers. On the left hand, however, schizophrenic men had lower digit ratios than healthy men.
“Asymmetry index showed moderate discriminatory power and, therefore asymmetry index has a potential utility as a diagnostic test in determining the presence of schizophrenia,” said Dr. Taner Oznur, an author of the study, in the press release.
Though no one is entirely certain why this link exists, researchers have hypothesized about a number of things. Past research has shown that exposure to high levels of testosterone or other hormones in the womb can actually impact brain development, raising a baby’s risk of schizophrenia and mental health disorders. This same exposure to hormones in the womb can, at the same time, influence the size and length of fingers.
But to what extent will doctors potentially be able to use such information in diagnosing schizophrenia? Probably not much, because even though these ratios are correlated with the disorder, this doesn’t mean they’re directly linked. In other words, simply looking at someone’s hands may offer vague clues as to whether they have a risk of schizophrenia — but it certainly won’t be a cut and dry diagnostic tool, at least not until further research is completed.
Source: Bolu A, Oznur T, Develi S, Gulsun M, Aydemir E, Alper M. The ratios of 2nd to 4th digit may be a predictor of schizophrenia in male patients. Clinical Anatomy. 2015.