PET links brain chemistry, personality

In the first study of its kind, German researchers have shown a correlation between healthy people's personalities and their brain chemistry using PET. Findings could lead to better understanding and treatment of addictive behavior.

Multiple studies have cemented the theory that genetic or acquired anomalies of the brain's endorphine or reward system influence the development of addictive behavior. Previous imaging research has found evidence that individuals with impaired reward systems are at higher risk of drug or alcohol abuse or pathological gambling.

The latest study shows that PET can detect subtle biochemical changes in the brains of healthy individuals. These "imbalances" could account for the traits deemed an individual's personality, according to coauthor Dr. Gerhard Gründer, a professor of psychiatry and psychotherapy at Aachen University.

"This has far-reaching implications," Gründer said. "Not only for choosing the best individual treatments, but also in discussions of an individual's free will."

Gründer and colleagues enrolled 23 men with no history of substance abuse who underwent PET with fluorine-18 fluoro-ethyl-diprenorphine, a radiolabeled agent that binds to neurotransmitters occurring naturally in the brain's reward system. Researchers compared PET scans with results of a temperament and character questionnaire that assesses human personality based on four dimensions: novelty seeking, harm avoidance, reward dependence, and persistence.

The investigators found that F-18 FDPN binding to opiate receptors in the ventral striatum correlated to an individual's degree of reward dependence. In other words, study subjects with a higher need for approval were also those with the highest endorphin uptake. The researchers published findings in the August issue of the Journal of Nuclear Medicine (2008;49(8):1257-1261).

Reward dependence is the only personality dimension correlated with opiate receptor binding, and that positive correlation was restricted to the ventral striatum, which is considered the key area of the human reward system and of the development of addictive behavior, said lead investigator Dr. Peter Bartenstein, a professor of nuclear medicine at the Ludwig Maximilians-University in Munich.

The novel finding will provide a deeper understanding of the functional relation among human personality, neurobiology, and addictive behavior, according to his colleague and principal investigator, Dr. Mathias Schreckenberger.

"Understanding the central role of neurotransmission processes in certain brain structures for the expression of psychologically defined constructs such as personality will make a great difference in the future of medicine," said Schreckenberger, a professor of nuclear medicine at Johannes Gutenberg-University in Mainz.

The researchers suggest that PET could become the imaging modality of choice for personalized treatment in a range of addictive personality disorders, such as drug abuse or compulsive gambling. PET can show specific changes in all neurotransmitter systems involved in addiction, which vary among people and among addiction types.

Study findings also suggest that PET could be used to predict response to drug abuse therapy and to determine treatment of other psychiatric diseases. PET may also play a role in the development and preclinical evaluation of new anticraving drugs, the researchers said.

For more information from the Diagnostic Imaging archives:

PET study links brain chemistry, behavior

3D MRI examines structural patterns of gray matter and bipolar disease

Functional MRI reveals clues to social behavior

Imaging genomics unveils roots of aggression