Yale Bulletin and Calendar

March 2, 2001

Volume 29, Number 21

Two-Week Issue

Study shows cocaine can harm brain permanently

Using an innovative method called transcranial magnetic stimulation (TMS) to measure brain responsiveness, Yale researchers have found that a cocaine ad-dict's response to stimulation is decreased, suggesting that cocaine may cause permanent brain damage.

"Contrary to what we expected, the results showed that cocaine-dependent individuals displayed increased resistance to brain stimulation," says Dr. Nashaat Boutros, associate professor of psychiatry and principal investigator on the study. "We expected them to be jumpy or more responsive because of the sensitizing effects of cocaine, but it took much stronger stimulation to get them to respond."

Boutros and his team examined 10 cocaine-dependent subjects (four men and six women) who had not used cocaine for at least three weeks and were addicted to no other drugs. A magnetic stimulus was delivered by TMS using a hand-held magnetic coil over the motor cortex, the part of the brain that moves the hands and fingers. The amount of magnetic stimulus needed to move the fingers is an indication of sensitivity in that part of the brain.

The results, published in the Feb. 15 issue of Biological Psychiatry, showed that those without cocaine addiction need about 35% to 55% of the output to move their fingers, while cocaine-addicted individuals sometimes need as much as 80%. "Somehow addicts have increased their resistance to the effect of the stimulus," Boutros says.

Boutros and his team started out with the theory that the longer people use cocaine, the more it causes symptoms like paranoia, panic attacks and seizures. "People have thought that a process called 'kindling' -- over time, less stimulus is needed to elicit the same response -- would apply to cocaine addicts," Boutros says. "But these results raise other possibilities."

The Yale researcher believes there are two theories that could explain the findings. One is that the cocaine caused widespread damage that decreased the brain's ability to respond to stimulation. "The other possibility," Boutros says, "is that the brain was indeed sensitized via the kindling response, and what we're seeing is a normal response from the brain, like an overcompensation. The brain feels too sensitive from all the cocaine jitter and cools off the response."

A follow-up study, Boutros says, will confirm this initial finding by examining a different group of cocaine-addicted people using additional TMS techniques. TMS has been used to study neurological disorders for 10 years, but was first used in exploration of cortical function in psychiatric disorders about three years ago.

Additional researchers on the study included Hajime Tokuno, Duane Campbell, of Yale and the VA-Connecticut Healthcare System; Robert Berman, Robert Mallison, John Krystal and Thomas Kosten of Yale; Sarah Lisnaby of Columbia University and Michael Torello of Capital University

-- By Karen Peart

Other Medical Center stories in this issue

Clinic eliminating pain of medical procedures for children

Study: Nurses rarely refer patients to hospice care

Shortened hospital stays do not affect recovery of PTSD patients, says report

British and Yale surgeons to share meeting of the minds

T H I SW E E K ' SS T O R I E S

Study shows cocaine can harm brain permanently

Forums explore democracy on local level

Director Spike Lee slams 'same old' black stereotypes in today's films

Head of NFL explains the economics of running a football league

Brooks appointed to Sterling Professor of French and Comparative Literature

Nordhaus is Sterling Professor of Economics

YCIAS awarded Carnegie grant to support study of globalization

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