More pressure in the brain
Cocaine use poses serious threats to brain function: it constricts the blood vessels in the brain, reducing blood flow and possibly causing long-term brain damage. This thesis is advanced in an article in the February 4, 1998 issue of the Journal of the American Medical Association. The findings, experts say, could explain brain damage and strokes in people who use cocaine in large quantities. Doctors have long known that cocaine puts a strain on the heart: blood pressure rises to dangerous levels. The extent of the effects on the brain, however, was previously less known. Now, pharmacologist Marc Kaufman and his colleagues at McLean Hospital in Belmont, Massachusetts and Harvard Medical School in Boston studied 24 he althy adult men who had previously used cocaine but were not addicts. The researchers injected the subjects with either a saline solution or a relatively small dose of cocaine and measured the blood flow in the subjects' brains 20 minutes after the injection using magnetic resonance angiography.
The researchers compared images of the subjects' brains before and after taking the drug to detect changes in blood vessel diameter or other signs of narrowing.
Five of eight subjects who received 0.4 mg of cocaine per kilogram of body weight showed such changes. According to Kaufman, drug users who take relatively small amounts are likely to experience comparable doses. Changes of a lesser magnitude occurred in three out of nine subjects who received half that dose. One in seven people who received the saline solution alone also had narrowing.
The researchers found that the changes were more pronounced in subjects who had used cocaine more frequently in the past. This suggests, says Kaufman, that cocaine use may have a cumulative effect.
Researchers speculate whether the narrowing of blood vessels could be related to the appearance of areas of low blood flow found in the brains of most cocaine users. These are blamed for memory loss and other brain damage. The narrowed blood vessels could also play a role in the strokes that sometimes occur. "It's like tightening an attacked pipe and putting more pressure on it at the same time," says Kaufman.
