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Cocaine May Age the Brain

24 April 2012 2:00 pm
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Karen Ersche/University of Cambridge

Old beyond years. A 3D model of merged imaging scans shows the brain areas affected by age (blue) in healthy people (left) and longterm cocaine users (right).

Add this to the list of reasons not to take cocaine: Chronic use of the drug may speed up the aging process. According to a new imaging study, cocaine abusers in their 30s and 40s show brain changes more commonly seen in people over 60. The finding also calls attention to the special medical needs of older drug users—a group that, until now, hasn't garnered much notice.

"Drug abuse is typically considered a young people's problem," says behavioral neuroscientist Karen Ersche at the University of Cambridge in the United Kingdom. But baby boomers, many of whom began experimenting with drugs when they were young, are getting older. And according to Ersche's research, some of them may be getting older faster.

Studies show that middle-aged drug abusers often have problems more commonly seen in the elderly, such as memory loss, increased susceptibility to infection, and higher rates of cardiovascular disease. Rates of premature death among drug abusers are up to eight times higher than in the general population, according to some estimates.

People addicted to cocaine also perform poorly on tasks that involve an area of the brain called the prefrontal cortex, such as memory, attention, and reaction time. Because elderly people can have similar mental impairments, Ersche wondered if chronic exposure to cocaine accelerates these changes in the brain.

To investigate, she and colleagues studied 120 people between the ages of 18 and 50. About half met criteria for cocaine addiction: They had used cocaine for an average of 10 years and had the drug in their systems on the day of the scan, according to urine tests. The other participants had no history of drug abuse or psychiatric problems. All subjects underwent magnetic resonance imaging scans, which the researchers analyzed with specialized software to reveal differences in the volume of brain structures.

Brain volume tended to decrease with subjects' age, consistent with other studies that have found that some brain shrinkage occurs normally as people grow older. But among cocaine users, the rate of shrinkage was almost twice that of the non-drug-using group (about 3 milliliters per year versus 1.7 milliliters for the non-drug-users), the team reports today in Molecular Psychiatry. Compared with drug-free people of the same age, the cocaine users also showed proportionally greater volume loss in prefrontal and temporal areas—the very areas that control the functions impaired in drug abusers. Alcohol consumption, which often goes hand-in-hand with cocaine addiction, did not seem to account for these changes. Even when the investigators removed the scans of 16 participants who were dependent on alcohol as well as cocaine, the link between cocaine use and brain volume loss remained.

"We are an aging society as it is," says Ersche. "If our young people are aging prematurely due to drug abuse, the public health implications could be huge."

"This is the first biological evidence I've seen that cocaine abuse may have an aging effect on the brain," says social scientist Caryl Beynon of Liverpool John Moores University in the United Kingdom. Beynon, who studies drug use in the elderly, notes that people who are growing older while using drugs have needs that may be unrecognized—especially if they have problems typical of those at an even more advanced age. Older drug users tend to be isolated and are often ashamed to admit to their drug problem, she says.

Beynon would like to see future research examine the effects of more casual use of cocaine and other drugs, since not everyone who uses drugs becomes addicted. She'd also like to see scientists track the changes in individuals over time. "It would be good to run a study scanning the participants once a year for a long period," she says.

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