In the wake of the Aurora movie theater shooting, many people are asking the same questions: What kind of derangement is indicated by the horrific acts of James Holmes? What is wrong with his brain? How will his mental state play out in the courts?

My goal here is to bring a perspective on this tragedy from the neurolaw point of view. As I write this (only 48 hours after the attack), there are few facts available about Holmes’ personality or mental health background. But even with this dearth of data a few observations can be made.

To begin, it’s critical to understand the difference between psychotic and psychopathic. These are two similar-sounding words that commentators sometimes use interchangeably—but they are completely different terms.

A person with a psychosis is disconnected from reality. For example, a homeless person arguing with himself is typically suffering from a psychosis such as schizophrenia. Someone with this sort of mental illness is termed “psychotic.”

A person with psychopathy, in contrast, does not empathize with other people. The psychopath can be smart, glib, charming, and blend in perfectly with the society around him, but he lacks empathy and guilt. Behind his “mask of sanity” lurks a manipulative creature who can hurt others without compunction. A psychopath (or synonymously, a sociopath) is someone like Jeffrey Dahmer or Ted Bundy. They are termed “psychopathic”.

Which (if either) was Holmes? Did he suffer from a mental illness such as schizophrenia, or was he instead a cognitively intact but an emotionless sociopath? When Colorado Representative Ed Perlmutter told the media that Holmes was “a psychotic son of a bitch”, I’m assuming his statement stemmed from a lack of understanding of the terms, rather than a specific suggestion that Holmes’ had schizophrenia in particular.

At this point there are insufficient facts to know Holmes mental state with certainty, but some clues might get us a step closer.

First, because the theater massacre and the apartment booby-trapping both required high levels of planning, schizophrenia seems less likely. Those with schizophrenia often have paranoia and grand delusions, but they also have a difficult time following through with ambitious plans. Judging by the months-long purchases of weapons, ammunition, and explosives, it would appear that Holmes had been meticulously planning his attack for some time.

Second, those with schizophrenia often (but not always) have a difficult time functioning in society. Holmes had an apparently exceptional undergraduate career and was two years into a graduate program. That certainly does not prove the absence of a psychosis, but it leans against it. To my mind, his neuroscience graduate school professors would have had no trouble detecting signals of schizophrenia in his class work: schizophrenics have a distinctive style of communication, characterized by tangential leaps between concepts.

In contrast, a person with psychopathy often flies below the radar, revealing nothing unusual. He can be perfectly capable of getting through a graduate program without triggering red flags. And his behavior in the theater—shooting victims serially, calmly, and randomly—has the flavor of a psychopath more than a person suffering from, say, a schizophrenic delusion of persecution.

As more data emerge about Holmes’ past and present, the question of his mental condition will be clarified. Of course, his problem could be something other than psychosis or psychopathy.

One suspect in bizarre acts like this is the presence of drugs (specifically, psychoactive drugs—those that effect the brain and can change cognition and behavior). But a drug-induced mental break seems less likely given his long-term pre-planning.

Another root of incomprehensible behavior can be a brain tumor, such as the dime-sized tumor impinging on the amygdala of Charles Whitman, the University of Texas tower shooter in 1966. Let me be clear that I see a brain tumor as an extremely low probability explanation in Holmes’ case, but it should be checked-out for completeness.

One does not have to be a neuroscientist to surmise that something is wrong with Holmes’ brain—but it matters what the problem turns out to be. The answer navigates his possible outcomes in court.

If Holmes is verifiably schizophrenic (with a historical medical record to back up the diagnosis), then his attorneys will plead not guilty by reason of insanity. If the plea is successful, he would be committed to a mental health institution—presumably for life. Historically, the public finds a successful insanity plea unsatisfying. However, even the ancient Greeks recognized that someone disconnected from reality cannot be treated the same way as someone with normally-functioning cognition.

If, in contrast, Holmes turns out to be a psychopath, he will not be able to plead insanity. For insanity defense purposes, one must have a mental illness, and psychopathy does not qualify. This is because psychopaths fully understand the nature and consequences of their crimes; they commit their acts simply because of a lack of compunction and remorse.

In the unlikely case Holmes has a brain tumor—and one which can be plausibly argued to have steered his behavior—this could serve as a mitigating factor during sentencing. Presumably, such a scenario would leave a bitter taste on the public tongue. On the one hand, everyone would agree that a behavior-changing tumor would not be his fault. On the other hand, the direct link between brain and behavior tends to go underappreciated during powerful emotional winds, and the desire for seeing punishment served is understandably strong. Therefore, the discovery of a brain tumor would test our capacity to deal with such horror in the light of modern biological understanding.

To summarize, it is unclear at the moment what would drive Holmes to such unfathomable behavior. Schizophrenia, psychopathy, drugs and brain tumors are all suspects that have reared their heads in other killings. Given the lack of data at the moment, I would guess that psychopathy is the more likely scenario. I will update the blog as more information becomes available.

Dr. David Eagleman directs the Initiative on Neuroscience and Law ( More of his views on the intersection of neuroscience and the legal system can be found in his book Incognito: The Secret Lives of the Brain.

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