Vol. 11, No. 2, 2005 Page 1&3
ADOLESCENT KILLERS EXHIBIT MARKED NEUROLOGICAL DEFICITS
A study of juveniles condemned to death reports compelling
evidence that they exhibited serious neurological impairment at
the time they committed their crimes.
Dorothy Otnow Lewis and colleagues evaluated 18 males who
had received the death penalty in Texas. All had been 17 years
old at the time they committed murder. At the time of the
evaluations, the subjects were in their mid-20s. Each subject
underwent neurological, neuropsychological, psychiatric, and
educational evaluations.
The researchers report that:
- Three subjects had been born prematurely (one weighing only
3 pounds), a fourth was delivered by Cesarean section because
the umbilical cord was wrapped around his neck, and the mother
of a fifth had attempted to abort him. Overall, the researchers
report, "six (33 percent) of the group began life with potentially
compromised central nervous system functioning, and a seventh
reportedly was the product of a difficult delivery."
- All but one of the subjects had a history of multiple head
injuries, often resulting in loss of consciousness.
- Neurological evaluation revealed that five of 17 subjects (one
did not undergo neurological testing) exhibited one abnormal
finding on testing of prefrontal lobe functioning, three had two
abnormal findings, two had three abnormal findings, and three had
four or more abnormal findings. "It should be noted," the
researchers say, "that most normal individuals have no signs of
frontal lobe impairment on neurological examination." In addition,
three subjects exhibited significantly impaired motor function.
- Neuropsychological testing revealed impairment on at least
two traditional structured tests of "executive functions" (brain
functions including planning and organization) in 10 of the
subjects. On the unstructured Iowa Gambling Task, which also
measures executive functions, 84 percent of subjects exhibited
marked impairment. Overall, the researchers say, "every subject
demonstrated signs of prefrontal cortical dysfunction on neurologic
examination, neuropsychological testing, or both."
- Psychiatric evaluation revealed that eight subjects had
histories and signs and symptoms consistent with early-onset
bipolar spectrum disorder, while another four had histories and
signs and symptoms consistent with early-onset schizoaffective
disorder. Of the remaining six subjects, the researchers say, "three
were clearly hypomanic" and one exhibited paranoia. Another
subject apparently had committed his crime while sleepwalking,
and his father had also exhibited parasomnia (unusual behavior
during sleeping). Many subjects reported experiencing dissociative
symptoms ("spacing out" or "out-of-body" episodes). Six had
started abusing alcohol or drugs before their 13th birthdays.
- All but one of the subjects came from very violent or abusive
families, "in which mental illness was prevalent in multiple
generations."
- Only one subject was mentally retarded, with one other
diagnosed as "borderline." However, six had lower reading scores
than would be predicted by their IQ scores. The majority showed
significant impairment in math, with 12 subjects exhibiting at least
a 20-point discrepancy between overall IQ and mathematical
reasoning ability scores. Eight subjects repeated grades in school,
and the other 10 had been placed in special education classes or
transferred to alternate schools. By second grade, more than one-
third were having serious problems in school; by sixth grade, 78
percent had been identified as needing special assistance
(primarily for emotional rather than intellectual reasons).
The researchers note that despite the clear neurological
impairments of their subjects, it appeared that only four had
undergone pretrial psychiatric evaluations, and none had received
pretrial neurologic or neuropsychological testing. Also, none had
received neuropsychiatric evaluations prior to sentencing.
"Unfortunately," they say, "in cases like these, a clinician's failure
to investigate thoroughly the psychiatric, neurologic, and
environmental factors influencing behavior can literally mean the
difference between life and death."
The researchers cite current evidence showing that the
prefrontal cortex and temporal lobes (both critical to reasoning and
self-control) do not mature until late adolescence. Teens with brain
dysfunction and/or mental illness, they note, would be even more
vulnerable to impairments in judgment and impulse control. Thus,
they say, "Our data... raise a question of ethics: to what degree
does it behoove our justice system to modify its criteria for
mitigation and culpability and adopt rules consistent with the
findings of early 21st century neuroscience?"
In earlier research involving adult murderers
(see related article, Crime Times, 1995, Vol. 1, No. 4, Page 1),
study coauthor Pamela Blake and colleagues reported that
"specific neurologic diagnoses could be established in 20 of the 31
subjects."
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"Ethics questions raised by the neuropsychiatric,
neuropsychological, educational, developmental, and family
characteristics of 18 juveniles awaiting execution in Texas,"
Dorothy Otnow Lewis, Catherine A. Yeager, Pamela Blake,
Barbara Bard, and Maren Strenziok, Journal of the American
Academy of Psychiatry and the Law, Vol. 32, 2004, 408-29.
Address: Dorothy Otnow Lewis, 10 St. Ronan Terrace, New
Haven, CT 06510, dorothy.lewis@yale.edu.