...neglect [was] the most powerful predictor of self-destructive behavior. This implies that although childhood trauma contributes heavily to the initiation of self-destructive behavior, lack of secure attachments maintains it. Those ... who could not remember feeling special or loved by anyone as children were least able to ...control their self-destructive behavior.
In this same paper, van der Kolk et al. note that dissociation and frequency of dissociative experiences appear to be related to the presence of self-injurious behavior. Dissociation in adulthood has also been positively linked to abuse, neglect, or trauma as a child.
More support for the theory that physical or sexual abuse or trauma is an important antecedent to this behavior comes from a 1989 article in the American Journal of Psychiatry. Greenspan and Samuel present three cases in which women who seemed to have no prior psychopathology presented as self-cutters following a traumatic rape.
Linehan (1993a) talks about people who SI having grown up in "invalidating environments." While an abusive home certainly qualifies as invalidating, so do other, "normal," situations. She says:
An invalidating environment is one in which communication of private experiences is met by erratic, inappropriate, or extreme responses. In other words, the expression of private experiences is not validated; instead it is often punished and/or trivialized. the experience of painful emotions [is] disregarded. The individual's interpretations of her own behavior, including the experience of the intents and motivations of the behavior, are dismissed...This invalidation can take many forms:Invalidation has two primary characteristics. First, it tells the individual that she is wrong in both her description and her analyses of her own experiences, particularly in her views of what is causing her own emotions, beliefs, and actions. Second, it attributes her experiences to socially unacceptable characteristics or personality traits.
This view is supported by evidence presented in Winchel and Stanley (1991) that although the opiate and dopaminergic systems don't seem to be implicated in self-harm, the serotonin system does. Drugs that are serotonin precursors or that block the reuptake of serotonin (thus making more available to the brain) seem to have some effect on self-harming behavior. Winchel and Staley hypothesize a relationship between this fact and the clinical similarities between obsessive- compulsive disorder (known to be helped by serotonin-enhancing drugs) and self-injuring behavior. They also note that some mood-stabilizing drugs (such as Tegretol, Depakote) can stabilize this sort of behavior.
Simeon et al. (1992) found that self-injurious behavior was significantly negatively correlated with number of platelet imipramine binding sites (self-injurers have fewer platelet imipramine binding sites, a level of serotonin activity) and note that this "may reflect central serotonergic dysfunction with reduced presynaptic serotonin release. . . . Serotonergic dysfunction may facilitate self-mutilation."
When these results are considered in light of work such as that by Stoff et al. (1987) and Birmaher et al. (1990), which links reduced numbers of platelet imipramine binding sites to impulsivity and aggression, it appears that the most appropriate classification for self-injurious behavior might be as an impulse-control disorder similar to trichotillomania, kleptomania, or compulsive gambling.
Herpertz (Herpertz et al, 1995; Herpertz and Favazza, 1997) has investigated how blood levels of prolactin respond to doses of d-fenfluramine in self-injuring and control subjects. The prolactin response in self-injuring subjects was blunted, which is "suggestive of a deficit in overall and primarily pre-synaptic central 5-HT (serotonin) function." Stein et al. (1996) found a similar blunting of prolactin response on fenfluramine challenge in subjects with compulsive personality disorder, and Coccaro et al. (1997c) found prolactin response varied inversely with scores on the Life History of Aggression scale.
It is not clear whether these abnormalities are caused by the trauma/abuse/invalidating experiences or whether some individuals with these kinds of brain abnormalities have traumatic life experiences that prevent their learning effective ways to cope with distress and that cause them to feel they have little control over what happens in their lives and subsequently resort to self-injury as a way of coping.
Much work has been done in behavioral psychology in an attempt to explain the etiology of self-injurious behavior. In a 1990 review, Belfiore and Dattilio examine three possible explanations. They quote Phillips and Muzaffer (1961) in describing self-injury as "measures carried out by an individual upon him/herself which tend to 'cut off, to remove, to maim, to destroy, to render imperfect' some part of the body." This study also found that frequency of self-injury was higher in females but severity tended to be more extreme in males. Belfiore and Dattilio also point out that the terms "self-injury" and "self-mutilation" are deceiving; the description given above does not speak to the intent of the behavior.
Two paradigms are put forth by those who wish to explain self-injury in terms of operant conditioning. One is that individuals who self-injure are positively reinforced by getting attention and thus tend to repeat the self-harming acts. Another implication of this theory is that the sensory stimulation associated with self-harm could serve as a positive reinforcer and thus a stimulus for further self-abuse.
The other posits that individuals self-injure in order to remove some aversive stimulus or unpleasant condition (emotional, physical, whatever). This negative reinforcement paradigm is supported by research showing that intensity of self-injury can be increased by increasing the "demand" of a situation. In effect, self-harm is a way to escape otherwise intolerable emotional pain.