"While many people try drugs, only some actually become addicted," said David Self, associate professor of psychiatry at the Yale School of Medicine. "There are clear differences in individual vulnerability to develop addiction. We are interested in finding out what brain mechanisms account for the differences."

Self and his colleagues tested three potential scenarios that might predict which animals would become addicted to cocaine. All of the test subjects were allowed to "self-administer" cocaine; then their access to the cocaine was removed, and craving for the drug was measured by the amount of lever-pressing they displayed in the drug's absence.

In the first test, the researchers looked to see if animals with higher activity in a new environment (so-called novelty seekers) would self-administer cocaine to excessive levels. The second test was designed to determine if being sensitized to cocaine in low doses could predict addictive behavior. "Neither a novelty response nor cocaine sensitization seemed to predict vulnerability to addiction," said Self, principal investigator on the research project. "Although sensitization to drugs occurs in addiction, it does not seem to underlie drug craving."

In the third test, however, Self and colleagues found that the animals with the highest craving responses in abstinence showed a dramatic escalation of cocaine intake prior to abstinence. " propensity for escalation and drug intake is, in itself, one of the criteria for addiction," Self said. "We have identified the addictive population, but what we don't know is how to screen these animals before they become addicted. We want to use this model to see if we can identify other behavioral features that predict which animals will show a vulnerability to develop cocaine addiction. We also want to know what is different about the brains of these animals."

The study is published in the May issue of the journal Neuropsychopharmacology.

COMMENTS ON THIS ARTICLE:

SUBMIT A COMMENT:

Note: Comments are now held for moderator approval. More info

Name:
Comment: (limit 250 words)
Enter this word (help):	Change

GUIDELINES: 
Please keep comments on-topic, courteous, clean, non-commercial, and within the word limit.
Read the complete guidelines