Reasons for Self-Injury discussed.
Etiology (history and causes)
Past trauma/invalidation as an antecedent
Van der Kolk, Perry, and Herman (1991) conducted a study of patients who exhibited cutting behavior and suicidality. They found that exposure to physical or sexual abuse, physical or emotional neglect, and chaotic family conditions during childhood, latency and adolescence were reliable predictors of the amount and severity of cutting. The earlier the abuse began, the more likely the subjects were to cut and the more severe their cutting was. Sexual abuse victims were most likely of all to cut. They summarize,
...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.
Invalidation independent of abuse
Although sexual and physical abuse and neglect can seemingly precipitate self-injurious behavior, the converse does not hold: many of those who hurt themselves have suffered no childhood abuse. A 1994 study by Zweig-Frank et al. showed no relationship at all between abuse, dissociation, and self-injury among patients diagnosed with borderline personality disorder. A followup study by Brodsky, et al. (1995) also showed that abuse as a child is not a marker for dissociation and self-injury as an adult. Because of these and other studies as well as personal observations, it's become obvious to me that there is some basic characteristic present in people who self-injure that is not present in those who don't, and that the factor is something more subtle than abuse as a child. Reading Linehan's work provides a good idea of what the factor is.
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...
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 invalidation can take many forms:
- "You're angry but you just won't admit it."
- "You say no but you mean yes, i know."
- "You really did do (something you in truth hadn't). Stop lying."
- "You're being hypersensitive."
- "You're just lazy."
- "I won't let you manipulate me like that."
- "Cheer up. Snap out of it. You can get over this."
- "If you'd just look on the bright side and stop being a pessimist..."
- "You're just not trying hard enough."
- "I'll give you something to cry about!"
Everyone experiences invalidations like these at some time or another, but for people brought up in invalidating environments, these messages are constantly received. Parents may mean well but be too uncomfortable with negative emotion to allow their children to express it, and the result is unintentional invalidation. Chronic invalidation can lead to almost subconscious self-invalidation and self-distrust, and to the "I never mattered" feelings van der Kolk et al. describe.
Biological Considerations and Neurochemistry
It has been demonstrated (Carlson, 1986) that reduced levels of serotonin lead to increased aggressive behavior in mice. In this study, serotonin inhibitors produced increased aggression and serotonin exciters decreased aggression in mice. Since serotonin levels have also been linked to depression, and depression has been positively identified as one of the long-term consequences of childhood physical abuse (Malinosky-Rummell and Hansen, 1993), this could explain why self-injurious behaviors are seen more frequently among those abused as children than among the general population (Malinosky-Rummel and Hansen, 1993). Apparently, the most promising line of investigation in this area is the hypothesis that self-harm may result from decreases in necessary brain neurotransmitters.
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.
Coccaro and colleagues have done much to advance the hypothesis that a deficit in the serotonin system is implicated in self-injurious behavior. They found (1997c) that irritability is the core behavioral correlate of serotonin function, and the exact type of aggressive behavior shown in response to irritation seems to be dependent on levels of serotonin -- if they are normal, irritability may be expressed by screaming, throwing things, etc. If serotonin levels are low, aggression increases and responses to irritation escalate into self-injury, suicide, and/or attacks on others.
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.
Knowing when to stop -- pain doesn't seem to be a factor
Most of those who self-mutilate can't quite explain it, but they know when to stop a session. After a certain amount of injury, the need is somehow satisfied and the abuser feels peaceful, calm, soothed. Only 10% of respondents to Conterio and Favazza's 1986 survey reported feeling "great pain"; 23 percent reported moderate pain and 67% reported feeling little or no pain at all. Naloxone, a drug that reverses the effects of opiods (including endorphins, the body's natural painkillers), was given to self-mutilators in one study but did not prove effective (see Richardson and Zaleski, 1986). These findings are intriguing in light of Haines et al. (1995), a study that found that reduction of psychophysiological tension may be the primary purpose of self-injury. It may be that when a certain level of physiological calm is reached, the self-injurer no longer feels an urgent need to inflict harm on his/her body. The lack of pain may be due to dissociation in some self-injurers, and to the way in which self-injury serves as a focusing behavior for others.
NOTE: most of this applies mainly to stereotypical self-injury, such as that seen in retarded and autistic clients.
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.
It should be noted that explanations involving operant conditioning are generally more useful when dealing with stereotypic self-injury and less useful with episodic/repetitive 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.
One hypothesis long held has been that self-injurers are attempting to mediate levels of sensory arousal. Self-injury can increase sensory arousal (many respondents to the internet survey said it made them feel more real) or decrease it by masking sensory input that is even more distressing than the self-harm. This seems related to what Haines and Williams (1997) found: self-injury provides a quick and dramatic release of physiological tension/arousal. Cataldo and Harris (1982) concluded that theories of arousal, though satisfying in their parsimony, need to take into consideration biological bases of these factors.