Do psychopaths have split brains? White matter studies point to brain hemispheric disconnect.

White matter image, coronal section

White matter image showing corpus callosum, from the White Matter Atlas, http://www.dtiatlas.org/

People with antisocial personality have white matter structural problems all over the place, including, interestingly, in the brain region that connects hemispheres, according to a recent study out of the UK.

Sundram F, Deeley Q, Sarkar S, Daly E, Latham R, Craig M, Raczek M, Fahy T, Picchioni M; UK AIMS Network, Barker GJ, Murphy DG. White matter microstructural abnormalities in the frontal lobe of adults with antisocial personality disorder. Cortex. 2012 Feb;48(2):216-29. Epub 2011 Jul 21. PubMed PMID: 21777912.

Previously, people with antisocial personality (a label we view as a proxy for psychopathy, although one could quibble that there are differences) were found to have white matter disconnects between the brain areas involved with emotion and those involved with reason on the right hand side. (Our post: Psychopath white matter: Abnormal mostly on the right hand side). This new report demonstrates a broader range of frayed white matter.

The report states [with our comments in brackets]:

FA was bilaterally reduced [white matter was messed up]  in the genu of corpus callosum while in the right frontal lobe FA reduction [white matter was messed up ] was found in the UF [a region previously reported], inferior fronto-occipital fasciculus (IFOF), anterior corona radiata and anterior limb and genu of the internal capsule. These differences negatively correlated with measures of psychopathy [in that the less messed up white matter, the higher the measure of psychopathy, which seems counterintuitive to us]. Also in the right frontal lobe, increased MD [messed up white matter] was found in the IFOF and UF, and the corpus callosum and anterior corona radiata. There was a significant positive correlation between MD [messed up white matter] and psychopathy scores.

We’ve always thought psychopathy – the high-functioning kind – was some kind of un-plugged white matter. (Our posts on white matter). We think of white matter as the wiring that connects brain functional modules, although the brain-as-a-bunch-of – functional-modules paradigm is on the wane. It’s more like a little of all sorts of functions is sprinkled over all sorts of brain parts. This makes for psychopathy flavors:  zillions of white matter disconnects and zillions of brain regions with zillions of functions.

Moreover, this recent report points to the corpus callosum — that hunk o’ white matter trunk line that connects hemispheres.  We think this explains a lot — psychopaths have split brain behavior in lots of ways. (See corpus callostomy –the well known split brain  studies demonstrated that different hemispheres showed different functions). People with full or partial corpus callostomies reportedly have defective moral reasoning.  Full and partial callosotomy patients reportedly based their moral judgments primarily on actions’ outcomes, disregarding agents’ beliefs, according to that report. And, much like psychopath ex post facto rationalizations “[i]n this study, it appears the patients sensed their judgments were not quite right, and they often offered rationalizations for why they judged the act as they did without any prompting. For example, in one scenario a waitress served sesame seeds to a customer while falsely believing that the seeds would cause a harmful allergic reaction. Patient J.W. judged the waitress’s action ‘permissible.’ After a few moments, he spontaneously offered, .’Sesame seeds are tiny little things. They don’t hurt nobody,’ as though this justified his judgment.” Now, does that sound like every psychopath that is in your orbit? Yes, of course it does.

The big picture is that the parts of the brain for emotion and correspondingly compassion are full of frayed connections to the parts of the brain thought to be involved with reasoning and planning.

The recent reports on child psychopathy brings all of this into high relief.  Another report on adolescent “conduct disorder” similarly reports under-developed white matter.

Sarkar S, Craig MC, Catani M, Dell’acqua F, Fahy T, Deeley Q, Murphy DG. Frontotemporal white-matter microstructural abnormalities in adolescents with conduct disorder: a diffusion tensor imaging study. Psychol Med. 2012 May 23:1-11. [Epub ahead of print] PubMed PMID: 22617495.

We suspect that brain re-wiring — whether for psychopathy or for stroke or trauma or whatever — will involve both behavior and some science. The science is tough. Our current fav is local brain stem cells combined with some kind of nasally administered . . . something. Some kind of brain stem cell mobilizing agent? BDNF? GDNF? Oxytocin? Leptin? G-CSF?