by Medical College of Georgia at Augusta
University
Sophisticated brain imaging, like an MRI, has
limited applicability in assessing a defendant's sanity, investigators say.
The bottom line of an insanity defense is the
defendant's inability to distinguish right from wrong at the time of the crime,
something which neuroimaging cannot help do, they say in a review article in
the journal Neuroethics.
"MRIs and other brain scans are good for
many things but they really have limited use when you talk about truly
determining if someone was criminally responsible or not," says Dr.
Michael J. Vitacco, forensic psychologist in the Department of Psychiatry and
Health Behavior at the Medical College of Georgia at Augusta University.
"The key element of an insanity defense
is you have to be unable to tell right from wrong," Vitacco says.
"It's that functional deficit that is critical. It's a very high
bar."
It's also an important distinction that means
the difference between a defendant going to jail or to a hospital, says the
article's corresponding author.
And, it's one that advanced brain imaging
technology, like functional MRIs and positron emission tomography, or PET
scans, which provide images of brain structure and insight into how the brain
is functioning, typically cannot help defendants seeking a not guilty by reason
of insanity verdict achieve.
But it's use is growing. Particularly in the
last decade, brain imaging, which routinely provides valuable, objective
information to a medical diagnosis, has been increasingly used in criminal and
civil cases. It even has a name, "neurolaw," with neurolaw centers
sprouting up across the country and beyond, Vitacco says.
"The problem is nobody talks about the
limitations of these images," says Vitacco who, along with colleagues at
the Medical University of South Carolina, Emory University and University of
Southern Mississippi, decided to take a look at research and evidence out
there.
No published studies they found showed the
ability of brain imaging to provide insight and evidence beyond the usual
exhaustive clinical evaluations of defendants, says Vitacco. These evaluations
may include talking with the defendant, with friends and family members,
possibly personality testing and medical record reviews looking for patterns of
behavior and for evidence that supports or contradicts an insanity defense.
Another issue is that brain images are taken
well after the crime, sometimes even a year or more after, and the dynamic
brain function images they display indicate what is happening at that moment,
not at the time of the crime, he says.
Scans can show evidence of serious mental
health problems like chronic depression and schizophrenia, as well as brain
tumors or brain damage. While problems like these may qualify defendants for an
insanity evaluation, a very small percentage of these individuals will meet the
high bar of not being able to distinguish right from wrong, Vitacco says.
As an example, pedophilia has been associated
with tumors in the front of the brain in areas involved with emotion and
memory, but they don't necessarily mean the offender did not know right from
wrong, Vitacco and his colleagues write. Even sociopaths typically know right
from wrong but choose to ignore it, Vitacco says.
What may better provide insight on many
defendants is social media, notes Vitacco.
He and Dr. Ashley B. Batastini, director of
the Correctional and Forensic Psychology Research Laboratory at the University
of Southern Mississippi, recently coauthored the book Forensic Mental Health
Evaluations in the Digital Age: A Practitioner's Guide to Using Internet-Based
Data.
They found these often multi-daily posts
about detailed thoughts and actions on social media can provide that
retrospective picture of what was happening in the mind of the defendant at the
time of the crime in the defendant's own words, says Vitacco.
"It really is powerful evidence, that
tells you a lot about their function, says Vitacco.
He notes, for example, a Georgia case when
the defendant was pleading insanity but his social media accounts at the time
of the crime included an instant message to a friend that he had done something
bad. "This kind of evidence can speak directly to knowing right from wrong
at the time a crime happens," Vitacco says.
While there is no accurate measure of how
often the defense of not guilty by reason of insanity is used, it is a
controversial issue both in the legal and general community, Vitacco and his colleagues
write. An insanity verdict is reached in less than 1% of cases, he notes.
Insanity evaluations are court ordered and
experts like Vitacco only make recommendations to judges and juries.
"Insanity evaluations are never easy, mainly because they are
retrospective," he says.
A 2013 University of Denver study of 165 defendants who each had multiple evaluations by either a forensic psychologist or forensic psychiatrist found unanimous agreement about legal sanity among evaluators only 55% of the time.
While recent years have seen a surge in brain
imaging in an insanity defense, its usage dates back much further, including
the 1982 trial of John Hinckley Jr., who shot President Reagan, and whose
defense team said had an abnormal CT scan that suggested "organic brain
disease." Hinkley was found not guilty by reason of insanity.
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