Can psychopathy be treated?

Some psychological conditions receive a disproportionate amount of attention in popular media relative to how frequently they actually occur in the population. One of those is psychopathy, a personality disorder that is characterized by antisocial behavior, impulsivity, and a lack of empathy. Psychopaths may be charming on the surface but tend towards pathological deception and indifferent manipulation of other people. And they are more likely to have behavioral problems or be involved in criminal behavior.

This description portrays the psychopath as a societal parasite, leaving little role in a community for such an individual other than as part of the criminal justice system. This turns out to be the reality for many psychopaths, who are estimated to make up only 1% of the general population but between 15-25% of the incarcerated population. But, as our criminal justice system is supposed to be designed to rehabilitate criminals, there is an important question regarding psychopaths that has yet to be answered: can psychopathy be treated? There is not a clear-cut answer to this question, and you might find a differing of opinion even among experts.

Neuroscience of psychopathy

One argument sometimes used in support of the idea that psychopaths are not truly capable of being treated is that studies have found brain abnormalities in psychopaths that might be associated with their deviant behavior. This argument becomes less valid, however, when we consider that there are neurobiological aberrations that can be detected in the brains of sufferers of any disorder. Just because there are predisposing neurobiological aspects of a disorder does not mean the disorder is untreatable; if this were the case, the list of psychological disorders we could treat would arguably be empty.

Studies with psychopaths have identified a number of neurobiological features that might be linked to the disorder. For example, abnormalities in limbic system function have been observed in psychopaths. The anterior cingulate cortex, part of a network that is activated when we observe other people experiencing pain, is one limbic area that has been implicated. In psychopaths, activation of the anterior cingulate when seeing others in pain is muffled. This has been interpreted as being partly responsible for the psychopath's reduced capacity for empathy. Other limbic structures hypothesized to play a role in psychopathy include the amygdala, hippocampus, and striatum.

There are also structural abnormalities in the brains of psychopaths. For example, studies have found psychopaths to have a larger corpus callosum, asymmetrical hippocampi, and deformed amygdalae. The significance of these structural differences, however, is not yet very clear.

Effectiveness of rehabilitation in psychopaths

As indicated, however, just because behavior is based in neurobiology doesn't mean it is immutable. If that were the case, we might as well give up on trying to change anything about ourselves. A more important question is if the research suggests that psychopathic behavior becomes less so with rehabilitation.

Unfortunately, there is not a straightforward answer to that question. Some do report that treatment may be beneficial. For example, studies by Caldwell et al. (2006) and Skeem et al. (2002) both found improvements in psychopaths with treatment (measured by likelihood of recidivism). However, other studies have obtained less optimistic results, ranging from little improvement in psychopathy with treatment to treatment seeming to exacerbate psychopathic behavior. All of the studies on psychopathy treatment have limitations, however, and there is not a well-controlled experiment that we can point to and feel confident that it tells us if psychopathy is treatable.

Influence on sentencing

One of the reasons it is important to know if psychopaths can be rehabilitated is that this information would likely have a significant influence on sentencing, parole hearings, etc. A study published a few years ago found that simply giving a judge information about the biology of psychopathy could lead to a reduction in the sentencing of a diagnosed psychopath (compared to a judge not receiving that information), even though the information didn't indicate psychopathy was treatable (in fact it implied the opposite). However, with or without information about the associated biology, a diagnosis of psychopathy may still add years to a sentence, as judges are more likely to consider the convict a continued danger to society.

With some reliable data about treatment to point to, we might be able to either provide evidential support for those extended sentences or justification for reducing them if proper treatment were provided (depending on what the data indicated). Right now, however, the data we have on rehabilitation of psychopathy is somewhat muddled, with some studies indicating it is possible and other studies suggesting treatment could actually make things worse. Until we have a more definitive answer, we should be hesitant about assuming psychopathy is untreatable; at the same time we should be exploring controlled experiments that allow us to obtain a better understanding of the response of the psychopath to rehabilitation.

Polaschek, D. (2014). Adult Criminals With Psychopathy: Common Beliefs About Treatability and Change Have Little Empirical Support Current Directions in Psychological Science, 23 (4), 296-301 DOI: 10.1177/0963721414535211




2-Minute Neuroscience: Divisions of the Nervous System

In this video, I discuss the divisions of the nervous system. The nervous system is primarily divided into the central nervous system and peripheral nervous system. But the peripheral nervous system is further subdivided into the somatic and autonomic nervous system, and the autonomic nervous system is also divided into sympathetic and parasympathetic fibers. All of these are discussed in this 2-minute video.

Know your brain: Corpus callosum

Corpus callosum (in red). CC image courtesy of Life Science Databases(LSDB).

Corpus callosum (in red).

CC image courtesy of Life Science Databases(LSDB).

Where is it?

The corpus callosum is a large, C-shaped nerve fiber bundle found beneath the cerebral cortex. It stretches across the midline of the brain, connecting the left and right cerebral hemispheres. It makes up the largest collection of white matter tissue found in the brain.

What is it and what does it do?

To understand the role of the corpus callosum, it is first important to remember that the brain is divided into two cerebral hemispheres (right and left). The hemispheres are made distinct from one another by a long groove called the medial longitudinal fissure. On a large scale, the two hemispheres are nearly identical, but on a microscopic and functional level there are some differences.

When information like sensory data is sent to the brain it is typically received first in one hemisphere. For example, when you type on the your keyboard, information about the feel of the keys is sent up from your right hand to the primary somatosensory cortex on the left side of your brain. That information, however, must then be shared with the right side of your brain as well. That's where the corpus callosum comes into play. It is a large bundle of fibers that connects the left and right hemispheres, and it carries information received in one hemisphere over to the other.

Split-brain patients

In the second half of the twentieth century, Roger Sperry, Michael Gazzaniga, and others studied patients whose corpus callosum had been severed in a procedure called a corpus callosotomy. The procedure is normally undertaken as a last-resort treatment of epilepsy, as it can stop seizures from spreading from one hemisphere of the brain to another. The patients became known as split-brain patients.

Surprisingly, a corpus callosotomy can be completed without severe side effects; the side effects that do appear are often language related. Sperry and Gazzaniga explored language deficits in callosotomy patients in detail. In the process, they learned some interesting things about how language centers are distributed across the cerebral hemispheres and how the corpus callosum facilitates communication between the two sides of the brain.

Sperry and Gazzaniga presented split-brain patients with visual stimuli, but only to one eye at a time. For example, they would present an image of a flower to the right eye, but cover the left eye. They found that split-brain patients, when presented with a visual image to only their left eye, could not name the object shown in the image.

Sperry and colleagues hypothesized that this occurred because visual information for the majority of the visual field travels to the opposite side of the brain to be processed. If the object is shown to the left eye, most of the information travels to the right side of the brain. Normally, this information would then be shared with the opposite hemisphere by way of the corpus callosum. The researchers suggested that split-brain individuals could not name the object if it was shown only to the left eye because the visual information was not reaching the left side of the brain, which is where our important language centers are located.

Much of what you've heard about one cerebral hemisphere being dominant in the management of a particular skill or capacity is probably exaggerated. For example, someone who is creative doesn't likely have an overall bias toward thinking with the right side of her brain. Instead, most skills are spread fairly evenly throughout both hemispheres. Language, however, appears to be an exception. In most people, speech is generated in the left hemisphere, and thus the left hemisphere is considered to be the dominant hemisphere for language.

Thus, according to Sperry and Gazzaniga, because language centers are located in the left side of the brain, when an image is presented to the left eye of a split-brain patient, the patient's language areas are not privy to the visual information. The information travels to the right hemisphere but does not cross back over to the left due to the severed corpus callosum. So, the ability to place a name to the object is limited.

These experiments helped to demonstrate the importance of the left hemisphere in language processing as well as the importance of the corpus callosum in bridging the two cerebral hemispheres. However, they also demonstrated the versatility and resiliency of the brain, as in most split-brain patients other tracts like the anterior commissure still carry enough information between the cerebral hemispheres to allow overall functionality to be somewhat normal.

Gazzaniga MS (2005). Forty-five years of split-brain research and still going strong. Nature reviews. Neuroscience, 6 (8), 653-9 PMID: 16062172