A three-dimensional model of Reinaldo Rivera's brain, created from date gathered in a PET scan, was shown at the trial. Andrew Davis Tucker/Staff

Experts debate brain data

Reinaldo Rivera has "diminished responsibility" for his crimes because a sophisticated brain scan shows he has little activity in an area responsible for impulse control and appropriate behavior, a defense expert testified.

ADVERTISEMENT

Related Links  • Visit the Rivera case special section

Have a thought? Go to the Forums or Chat.

Subscribe  E-mail this story  Write a letter to the Editor  Printer-friendly version  Get news on your PDA  Get e-mail headlines

Neuropsychiatrist Thomas Sachy points to an MRI scan of Reinaldo Rivera's brain during Mr. Rivera's trial. Dr. Sachy argues that Mr. Rivera is mentally ill because of a lack of activity in the defendant's orbital frontal lobes. Andrew Davis Tucker/Staff

But specialists in the field who are not involved in the case said the science doesn't support the conclusions.

In Richmond County Superior Court, neuropsychiatrist Thomas Sachy presented images Tuesday from a positron emission tomography scan, or PET scan, of Mr. Rivera's brain. It displays brain areas based on cell activity. Dr. Sachy noted little going on in the orbital frontal lobes of Mr. Rivera's brain when compared side by side with a normal brain scan he obtained from a California lab.

"Judgment, social mores, tact, impulse control, this is where that is in the brain," Dr. Sachy said. "Mr. Rivera's is quiet."

But it is not valid to compare scans from two different machines with patients performing under different circumstances, said Helen Mayberg, a former professor of neuropsychiatry at the University of Toronto who recently relocated to Emory University. She has been using PET scans to study brain circuitry and psychiatric disorders since the 1980s.

"These scans are very, very sensitive," she said, and little things can make a difference. "Showing the pictures side by side is very misleading."

Also, that area of the brain might not be the one responsible for impulse control, said Manuel Casanova, a neuropathologist and professor of psychiatry at the University of Louisville.

"First of all, trying to locate the (center) of impulse control within the brain that way really is not proper," Dr. Casanova said. "If anything, there would be several other candidates."

And activity in that area can change based on patient motivation. Schizophrenics might show little activity in that area, a condition called hypofrontality, until offered a reward for doing the test, Dr. Casanova said.

"If you were to offer those patients cigarettes or coffee, blood flow would be back to normal," Dr. Casanova said. "Many people have actually said that the hypofrontality exhibited by the patients is really a motivational or attentional deficit. It doesn't have to do with impulse control."

Yet Dr. Sachy said his findings, along with an MRI that showed Mr. Rivera's brain shrinking and interviews and exams, led him to diagnose Mr. Rivera with antisocial personality disorder, obsessive-compulsive disorder and a sadistic form of paraphilia, sexual deviancy.

"He has an obsession with violent, deviant sexual acts committed on women," Dr. Sachy said. "His compulsion is doing them."

And the dysfunctional brain interfered with his ability to control them, Dr. Sachy said.

"My clinical opinion is that without a properly functioning frontal lobe, you have diminished responsibility," Dr. Sachy said. "Given the nature of what he's done, it would be difficult to say absolutely no responsibility."

But PET scan readings of low activity in the frontal lobe wouldn't fit with obsessive-compulsive disorder, Dr. Mayberg said.

"Obsessive-compulsive disorder has overactive frontal lobes," Dr. Mayberg said. Nor do the findings seem to fit his crimes, she said.

Dr. Sachy cited a study that showed violent criminals tend to have problems in their frontal lobes, but Dr. Mayberg said that was a flawed study and didn't seem to fit this crime. Mr. Rivera is accused of raping and killing four Augusta-area women.

"There is no data that says people who are serial, premeditated predators have abnormalities of their frontal lobe," she said.

And the whole premise of the scan is mistaken, Dr. Casanova said.

"Making a correlation between blood flow and impulse control is flawed, period. Bad science," he said.

Reach Tom Corwin at (706) 823-3213 or tom.corwin@augustachronicle.com.

--From the Wednesday, January 21, 2004 printed edition of the Augusta Chronicle