Lee S H, Weinlander M M
J Clin Psychol. 1976 Oct;32(4):843-4. doi: 10.1002/1097-4679(197610)32:4<843::aid-jclp2270320425>3.0.co;2-z.
The relationship between childhood onychophagia (fingernail biting) and the suicidal and nonsuicidal mean age among 150 hospitalized psychotic veterans was investigated. The results show that the suicidal mean age is significantly younger than the nonsuicidal mean age and that the childhood onychophagia variable "focal suicide" significantly lowers the mean age of suicidal veterans, but does not significantly lower the mean age of nonsuicidal veterans.