Report: Cocaine users have less gray matter

Seeking to uncover the biological underpinnings of cocaine addiction, Long Island scientists have found that abusers of the drug possess less gray matter in key areas of the brain.

The discovery, reported in the current the Journal of Cognitive Neuroscience, suggests how brain structure governs a potentially devastating pattern of behavior, scientists say.

"Reduced gray matter may culminate in the compromised ability to experience pleasure and control behavior, especially in high-risk situations," said Muhammad Parvaz, a post-doctoral fellow at Brookhaven National Laboratory and a lead investigator of the research.

Parvaz said only additional studies will determine if cocaine abusers are born with the gray matter deficit or develop it after years of drug use. He theorizes the former.

Gray matter is made up of neurons, the basic cellular building blocks of the cerebral cortex, which is associated with all higher human functions. Scientists have long estimated there are more neurons in the three-pound human brain than stars encrusting the universe.

But the team found dramatically less gray matter in key brain regions associated with decision-making and thought-processing in cocaine abusers.

Abusers, Parvaz noted, are less likely to consider consequences, especially when faced with stress or when cravings arise. In either situation, they turn to the drug, he said.

Addiction experts not associated with the investigation say the findings open a new window into understanding why people abuse cocaine, and possibly other drugs as well.

Jeffrey Reynolds, executive director of the Long Island Council on Alcoholism and Drug Dependence in Mineola, said the discovery is welcome news.

"Increasingly there is a whole body of research focusing on addiction as a brain disease," he said, "and the implications are significant not only in terms of treatment but prevention."

Ferreting out the biology of addiction "helps reduce the stigma" faced by those whose lives are dominated by drug or alcohol abuse, Reynolds said.

Dr. Stephen Dewey, director of behavioral and molecular neuroimaging at the Feinstein Institute for Medical Research in Manhasset, said, "There have definitely been reports in the scientific literature of [brain] anatomical differences for patients with schizophrenia, but this is the first time I've heard of it with respect to cocaine abuse."

Brookhaven announced similar findings last year in research involving alcoholism. The lab has been on a decades-long pursuit to unlock the chemistry -- and now the anatomy -- of addiction.

Scientists conducted a series of MRI scans on 39 volunteers, 17 who never used drugs and 22 with a history of cocaine abuse.

To determine whether decision-making differed, scientists placed electrodes on volunteers' scalps to measure a brain signal known as the P-300, a well-known electrical marker associated with pleasure and reward.

In the non-addicted, the P-300 increased in magnitude as the monetary reward grew. Volunteers had prospects of earning rewards up to 45 cents for each correct answer in the test. The ultimate amount to be earned: $50.

The brain signal in cocaine-addicted volunteers essentially flat-lined throughout the test. Their sense of reward -- pleasure -- was never satisfied, Parvaz said, a characteristic seen throughout the spectrum of drug and alcohol abuse.