PET study finds connection between chemistry, behavior

One of the most interesting topics in science today is the relationship between the mind and the brain. Its study is being propelled particularly by the use of nuclear medicine imaging, and this theme was echoed throughout the 2007 SNM meeting.

Establishing a clinical context for such studies is not easy, and they may leave scientists with more questions than answers. By believing that more knowledge will help prevent or diagnose and treat every disease or condition that afflicts humankind, science may overestimate its reach. Yet studying these issues remains vital.

The more understanding of the basis of life and of human identity and behavior we have, the better scientists and clinicians will be able to intercede when health turns into disease and social behavior becomes problematic, according to Dr. James H. Thrall, chief of radiology at Massachusetts General Hospital, who spoke at the meeting.

"The advantage of imaging is its objectivity compared to simply clinically evaluating people with behavioral or psychiatric afflictions. The use of imaging to phenotype patients for clinical trials and for gene discovery will become extremely valuable," Thrall said.

His message was bolstered by the choice of the SNM Image of the Year, which came from a study by Nelly Alia-Klein, Ph.D., an assistant scientist, and colleagues at Brookhaven National Laboratory. Using PET with carbon-11-labeled monoamine oxidase A inhibitor clorgyline, researchers found an association between MAO-A brain activity and violent behavior. Subjects with lower MAO-A brain activity reported more aggressive behavior in a personality questionnaire and vice versa. The results indicate that an individual's genetic and brain makeup can influence aggressive behavior, even if that individual has no history of personality disorder, Alia-Klein said.

"Psychiatric illness is the number one cause of disability around the world," Thrall said. "Depression in particular steals people's ability to enjoy their lives. If we can understand the link between this multifaceted condition and what we can see on images of the brain, we will have an incredibly powerful tool."