I'm sure everyone here has heard of self-inflicted harm, or self-injurious behavior. The common word for it is "cutting", and professionals and parents often worry about its presence in adolescent populations. But the population in which self-injurious behavior is most prevalent is actually in patients (adult or adolescent) with borderline personality disorder.
Borderline personality disorder (for some reason I wrote this up the first time as bipolar, but it's IN THE TITLE. How tired am I. I blame Mr. S) is a disturbance in personality disorder which goes back and forth between self blame and blame of others, and which almost always include both severe emotional highs and severe emotional lows. The jury is still out on how exactly this works and what's going on in the neural circuitry of people with BPD, but right now what we know is that they appear to have a lot of trouble regulating their emotions.
Yeah, duh, you might say. But it's not as simple as just telling someone to calm down. What appears to be going on in BPD patients is that they have an overfunctioning of the limbic system of the brain, which is a group of brain areas associated with things like fear, emotion, and other behaviors. So if you have an overfunctioning in these areas, you might expect greater emotional highs and lows.
But the limbic system is restrained in part by input from the prefrontal cortex, that big area in the front of your brain which is devoted to what we like to call "higher function", and which is often responsible for inhibiting impulsive behaviors and emotions. People with BPD ALSO have a dysfunction in THIS area, in particular what appears to be a hypofunctional system. So this means they are getting too much emotion from the limbic system, and too little reigning in from the prefrontal cortex. The result is a very dysregulated emotional state, with really high highs, and very low lows.
And one of the ways that people with BPD often attempt to deal with their excess emotion is through self-injurious behavior. Why is that?
Well, ok, this paper doesn't work out the why. But it tries. And it may be on to something.
So for this study, the authors wanted to look at people with borderline personality disorder in strong emotional situations, and then look at their response to pain. To this end, they shoved them all in an MRI, and showed them pictures. These pictures were from the International Affective Pictures System, which is a database of pictures that has been developed by psychologists since the 1980's. This contains pictures that would produce positive emotions (or affect, pictures like puppies and kittens and flowers and stuff, possibly hungover owls), pictures of neutral things (neutral faces, chairs, apples), and range to highly negative stimuli (surgical pictures, sexually explicit images, and violence). The positive and negative pictures are capable of eliciting some very strong emotions (as you might imagine).
So they took both people with BPD, and controls, and showed them these pictures. And they looked at areas of the brain to look at how people reacted to either negative or neutral images.
Above you can see the graphs for different areas of the limbic system (top two are the amygdala, associated with things like fear and strong emotion, the middle two are the insula, and the bottom two are the anterior cingulate cortex, all of which are associated with emotion and behavior). The grey bars are the borderline patients, and the white bars are the controls. The left half of each graph is negative pictures, and the right half is neutral pictures. You can see that the BPD patients, across the board, had a bigger brain activity response to the negative pictures (which correlated with their own reports of having difficulty controlling their emotions, though I don't think they actually took subjective report data on how the pictures made the patients feel). They also often had a bigger limbic system response to the neutral pictures, which suggests that BPD patients have a higher limbic system response to just about anything compared to controls, and goes along very well with previous studies showing this.
But then, they took these same patients, and these same pictures, and while the patients were viewing them, they gave them PAIN in the form of a heat thingy on the leg. Sci has been in a pain study with a heat thingy on the leg. It's really, really annoying. What they wanted to see was whether the pain of the heat pad caused bigger changes in the BPD patients. They appear to have a higher tolerance for pain in the first place, which is something I think could stand some further studies on its own.
And this is where Sci started pleading with the data to SHOW me something. To SPEAK to me. Because the data looks like this:
And I cannot for the life of me figure it out. So many lines, all meaning different things and going in different ways! I can never tell why people display data this way (I see it all the time), and Sci's best guess is that they are worried people will get bored looking at piles of bar graphs. I assure you, if the data speaks to me, Sci doesn't get bored. I figured it out eventually, never fear.
Anyway, from what I can tell, the application of heat pain appears to bring down the activation in the amygdala when the patients see negative pictures (the top two panels). This looks liked it worked for both the the BPD patients and the controls, with both heading toward baseline in almost all cases. Unfortunately, this worked for both when the heat pad was HOT, and when it was WARM. Which kind of takes away the idea of pain deactivating the limbic region, which was the hypothesis they were going for. In addition, the fact that the warm and hot heat pads decrease limbic activation in both the BPD patients and the controls doesn't really help the hypothesis that this was a mechanism in BPD patients only.
But what's interesting about this study is that the patients all responded to the hot or warm pad with changes in brain activation. While this doesn't really look like much at first glance, it COULD mean that it's not the PAIN that matters. It's the sensory stimulus. The actual feeling of something happening. It's DISTRACTING. The authors propose (though they couldn't test this in the paper, I assume they are coming up with ways to test this if not actually testing it already) that it's the attentional shift that is important to people with BPD. The emotions are so intense that relief comes when you are distracted from them. Other studies have shown signs of this as well, with people with BPD having a better time dealing with emotional highs and lows when they have to do tasks that require a LOT of attention.
And this implies that when people with BPD self-injure, it may not be a relief of the emotions, rather than just a distraction, which in turn decreases the activation in the brain and provides some relief. This doesn't mean that self-injury is a good thing, far from it. But it DOES mean that, if this hypothesis turns out to be true and distraction works very well to help people with BPD, that we could come up with behavioral treatments to help combat their episodes of severe emotion. Things that they have to do which will distract them, and then help them to deal with emotional surges, and possibly stop the cycle of self-and-other blame that can make them very difficult to identify and treat.
There's more to this as well. Because of the results that the authors showed with high results in the amygdala, and because we know that people with BPD have high levels of limbic activation, we may be able to discover treatments for BPD by targeting areas like the amygdala specifically to reduce its activity and thus help to control the surging emotions. Right now we only have drugs that damped affect all over the brain, and while this does work, it also is very non-specific and has side effects. With modern technologies and more research, we may be able to come up with a treatment that is both more sensitive and more specific.
Niedtfeld I, Schulze L, Kirsch P, Herpertz SC, Bohus M, & Schmahl C (2010). Affect regulation and pain in borderline personality disorder: a possible link to the understanding of self-injury. Biological psychiatry, 68 (4), 383-91 PMID: 20537612