The ratio between the lengths of the index and ring fingers may predict schizophrenia in males, according to a study published in Clinical Anatomy.
In males, the ratio may indicate a predisposition to disorders related to abnormal hormonal balances. Having an index finger that is shorter than the ring finger is a result of high exposure to testosterone in the uterus, referred to as the 2D:4D ratio (for second digit to fourth digit).
Previous studies have suggested that greater exposure to testosterone in the uterus is linked to the development of schizophrenia. The researchers in this study wanted to take that idea further to see if the 2D:4D ratio could predict schizophrenia.
The study included 103 male patients who had been diagnosed with schizophrenia and 100 healthy male controls. The researchers measured the lengths of the participants’ fingers and looked at the ratios between finger lengths.
The researchers found that the participants with schizophrenia had asymmetrical ratios on the right and left hands. On their right hands, those with schizophrenia had a higher 2D:4D ratio than controls. On their left hands, they had lower 2D:4D ratios than controls.
"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 Taner Oznur, MD, from Gulhane Military Medical Faculty, Department of Psychiatry, Ankara.
The ratio of the lengths of the index finger and the ring finger in men may be an effective predictor of schizophrenia, scientists have found.
Turkish researchers found that the ratio of the lengths of the second digit (2D) and fourth digit (4D) may be predictive of a variety of disorders related to disturbed hormonal balance in males.
When the index finger is shorter than the ring finger, this results in a small 2D:4D ratio, pointing to a high exposure to testosterone in the uterus, researchers said.