The brains of psychopaths have a significant physical difference from those of non-psychopaths, says a new study.
In a psychopath’s brain, white matter (connective neural tissue) links between the ventromedial prefrontal cortex (vmPFC) and amygdala are unusually weak. This means a major brain area involved in anticipating risk (the vmPFC) is only weakly connected with an area crucial for processing fear and sadness.
Though the word “psychopath” gets thrown around a lot, it doesn’t necessarily refer to a maniacal killer. It’s simply a term used to characterize personality disorders in which a person has difficulty linking their actions with feelings like empathy, regret, and guilt.
Because many psychopathic individuals learn to mask their difficulty experiencing these linkages, they often don’t get the therapies they need – so many do, in fact, end up committing crimes; or at least making life tough for their friends and family. Even as we get better at understanding the symptoms of psychopathy, though, the causes have remained somewhat poorly understood.
But now, as the Journal of Neuroscience reports, a team of researchers from several institutions have joined forces to study the neuroanatomy of psychopathic prisoners in detail.
The University of Wisconsin’s Joseph Newman has spent years studying and working with psychopathic prisoners in the Wisconsin state correctional system. Newman teamed up with Kent Kiehl, a psychologist from the University of New Mexico, who brought a mobile fMRI scanner to a Wisconsin prison and took detailed scans of 20 psychopathic prisoners’ brains. The team also took diffusion MRI scans, which are useful for precisely mapping tiny anatomical structures deep within the brain.
When the team compared this data against equivalent scans of 20 non-psychopathic prisoners’ brains, they found that psychopathic prisoners’ brains showed some significant structural abnormalities:
Using diffusion tensor imaging, we show that psychopathy is associated with reduced structural integrity in the right uncinate fasciculus, the primary white matter connection between vmPFC and anterior temporal lobe.
In short, the white matter connecting the vmPFC to the amygdala isn’t particularly sturdy in psychopaths’ brains. This abnormality is also related to some major functional differences:
Using functional magnetic resonance imaging, we show that psychopathy is associated with reduced functional connectivity between vmPFC and amygdala as well as between vmPFC and medial parietal cortex.
In other words (as you might expect) the lack of healthy white matter connectivity means the vmPFC doesn’t communicate with the amygdala very well in psychopaths’ brains.
This study provides some of the first clear data on just what it is, in specific anatomical and physiological terms, that makes the brain of a psychopath different from yours or mine.
While these discoveries don’t let these prisoners off the hook for the crimes they committed, the data does provide encouragement that more targeted therapies could help prepare psychopathic individuals to lead healthy lives in the outside world. It also reminds us that “the criminal mind” may be as much a medical concern as it is a moral one.
And that, I think, is good news both for psychopathic individuals and for the rest of us.