In what seems at first an obvious conclusion, researchers at Johns Hopkins and the National Institute on Drug Abuse have found that people who "do" both cocaine and alcohol risk a worse loss of brain function than those who frequently use either drug alone.
"You could say this is a 'no brainer' sort of study," says Hopkins neuropsychologist Karen Bolla, who led the research team. "That two drugs are worse than one is something you'd expect. But very little science exists on how using both drugs affects the brain," Bolla says. "Since cocaine and alcohol use often go hand in hand in the real world, these studies were acutely needed." One result of the study, for example, suggests that cocaine use may somehow make the brain more sensitive, lowering the amount of alcohol it takes to hobble brain abilities, she adds.
In a study reported in the July issue of the journal Neurology, the researchers gave 56 chronic cocaine abusers a battery of neuropsychological tests, each geared to measure a specific brain ability. All the participants also drank liquor, but half of them drank more than 10 times a week.
The coke/alcohol users had been "dry" for at least a day at the time they were first tested. They were tested again after four weeks of abstinence.
Results showed that each drug takes a unique toll. "We found that people with a heavy use of alcohol don't do as well at executive abilities like planning ahead and organizing," Bolla says. "Those with a heavy cocaine habit have less ability to concentrate, and score higher in impulsive activity. The take-home message is that taking both drugs is additive; users experience the whole range of losses."
One of the study's strengths, Bolla says, was that researchers questioned people on their lifetime drug use and translated that into specific numerical results. For the first time, she says, scientists could show how the degree of a person's drug habit relates to brain performance. For both cocaine and alcohol, she adds, the greater the weekly drug amount, the worse people do.
"This research won't cure anything but could improve ways we treat addiction," Bolla explains. "All the years of 'reefer madness' stories have done little to discourage people from becoming addicted. But here are hard data. This is real. When we tell people, 'Look. High doses of these drugs can do this,' we hope now they'll listen.
"One other major benefit of this study lies in helping to tailor addiction treatment," Bolla says. "Long-term use of these drugs actually is damaging to the very parts of the brain that make it possible to quit. So you have to work around that."
"If you did these cognitive tests on people as soon as they begin a treatment program, you'd know, for example, that visual memory's knocked out. So you could present things verbally. You'd know that people who don't have executive skills can't make a plan of action and carry it out. So you find another approach."
Other scientists in the study were Jean Lud Cadet, with NIDA, and Frank R. Funderburk, with In Compass Systems, Baltimore.
NIDA funding supported the research.