There are physiological indicators for self-injurious behavior.
Self-Injurers have lower levels of Serotonin, an important neurotransmitter. Neurotransmitters conduct impulses between nerve cells in the brain. Serotonin, specifically, regulates impulsivity and aggression.
In addition, lower levels of respiratory sinus arrhythmia, a measure of heart rate with breathing, were also found. Such levels can also be found in people suffering from depression or anxiety, as well as delinquent boys.
Much of the focus has been on the psychological causes of such behaviors. But it is important to examine physiological causes that make one more at risk, at the very least, to engage in these destructive behaviors.
Source
Researchers find physiological markers for cutting, other self-harming behaviors by teenage girls
