Study: Brain Structure Different Among Cocaine Users

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Study: Brain Structure Different Among Cocaine Users

11/19/2004

 

New research from Massachusetts General Hospital finds that

individuals addicted to cocaine have a different brain structure than

non-users, which may make it difficult for users to determine the

consequences of their actions, the BBC reported Nov. 18.

 

For the study, researchers performed magnetic resonance imaging (MRI)

scans of the brains of 27 individuals addicted to cocaine and a group of

non-users of the same age and background. From the scans, the researchers

created 3D images of the brain to examine the volume of the amygdala in

participants. The amygdala is an almond-shaped section of the brain strongly

involved in emotional response.

 

According to the findings, the amygdala in cocaine users was 13

percent smaller on the left side of the brain and 23 percent smaller on the

right side than in non-users.

 

The study's findings are published in the Nov. 18, 2004 isssue of the

journal Neuron.

 

 

 

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Study: Cognitive Deficits Linked to Cocaine Misuse

11/17/2004

 

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Scientists have concluded that cocaine misuse is linked to dysfunction

in areas of the brain that are involved in higher thought and

decision-making, according to the National Institute on Drug Abuse (NIDA).

 

The study, conducted by Dr. Robert Hester of Trinity College in

Dublin, Ireland, and Dr. Hugh Garavan of Trinity College and the Medical

College of Wisconsin in Milwaukee, involved 15 active cocaine users and 15

healthy individuals who have never used the drug.

 

For the study, participants completed a task in which they had to view

memory lists of letters for 6 seconds and " rehearse " each list for 8

seconds. The participant then pressed a button when they were presented with

a letter that was not part of the preceding " memorized " list.

 

During the task, the researchers analyzed the participants' brains

using functional magnetic resonance imaging (fMRI), a noninvasive imaging

technique that illustrates nerve-cell activity during the performance of a

specific task.

 

The researchers found that those who misuse cocaine were significantly

less proficient than non-drug users at accurately completing the task.

 

The study showed that the demands of working memory required increased

activation of two brain regions, the anterior cingulate cortex (ACC) and the

prefrontal cortex. These areas have been consistently associated with memory

and higher brain function.

 

" Previous research that examined cognitive function in cocaine abusers

identified decreased activity in the ACC, " said Garavan. " But our study is

the first to show that the difficulty cocaine users have with inhibiting

their actions, particularly when high levels of reasoning and

decision-making are required, relate directly to this reduced capacity for

controlling activity in the ACC and prefrontal regions of the brain. "

 

The researchers concluded that cognitive deficits are part of the

reason why individuals who misuse cocaine persist in using the drug or

return to it after a period of abstinence.

 

The study's findings will be published in a future issue of the

Journal of Neuroscience.

 

 

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Cocaine May Compromise Immune System, Increase Risk of Infection

4/23/2004

 

 

 

Research Summary

by Patrick Zickler

NIDA NOTES Staff Writer

 

Cocaine abusers are more likely than nonusers to suffer from HIV,

hepatitis, sexually transmitted diseases, and other infections. Most of this

increased incidence is the result of conditions and behaviors -- for

example, injecting drugs, poor nutrition, and unsafe sex -- that often are

associated with drug abuse. Now, NIDA-supported investigators at the McLean

Hospital Alcohol and Drug Abuse Research Center in Belmont, Massachusetts,

have found that cocaine itself has a direct biological effect that may

decrease an abuser's ability to fight off infections.

 

Dr. John H. Halpern, along with colleagues at McLean Hospital and

Harvard Medical School, found that a key immune system component, a protein

called interleukin-6 (IL-6), responded less robustly to an immunological

challenge in male and female abusers injected with cocaine than in those who

received placebo. " When your body detects a foreign object, IL-6 helps

trigger the release of a cascade of other immune system components that

isolate and neutralize the threat, " explains Dr. Halpern. " If the balance of

this response is disrupted, your body cannot fight infection as effectively

as it should. "

 

The study involved 30 participants (16 women, 14 men, ages 21-35) with

a history of cocaine abuse, including at least one drug administration

within the past month. The investigators placed an intravenous catheter in

one arm of each participant and measured IL-6 levels. The catheter is

detected as foreign by the body's immune system and triggers an immune

response. After 30 minutes, the researchers injected cocaine or saline

solution (0.4 mg/kg) into each participant's other arm; 4 hours later, they

measured IL-6 levels again. In participants given saline, IL-6 levels had

more than quintupled in response to the presence of the catheter, increasing

from an average of less than 2 trillionths of a gram (picograms, or pg) per

milliliter of blood to an average of more than 11 pg/ml. In men and women

who received cocaine, however, IL-6 levels barely doubled--from less than 2

pg/ml to an average of 3.8 pg/ml.

 

" The findings in this study show that in people with a history of

cocaine abuse, exposure to the drug establishes conditions that can lead to

immediate harm, " Dr. Halpern says. " In such subjects, we found that cocaine

impairs the body's defense system for at least 4 hours. We can't rule out

the possibility that IL-6 response returns to normal shortly after that

time. But even if the blunted immune response lasts only a few hours, it

makes it more likely that an infection like HIV or just a common cold can

take hold, " Dr. Halpern says.

 

" This research suggests a link between cocaine use and compromised

immune response and could help explain the high incidence of infectious

disease among drug abusers, " observes Dr. Steven Grant of NIDA's Division of

Treatment Research and Development. " It reminds us that the health

consequences of drug abuse reach far beyond disruption of the brain systems

involved in abuse and addiction. "

 

The findings also have significance in another context, Dr. Grant

adds. " The IL-6 findings are a small but possibly significant part of a much

larger study designed to gather a wide range of information on the acute and

chronic effects of abused drugs on the brain, endocrine system, and immune

function. This kind of discovery-based research can yield unexpected,

sometimes important, insights. "

 

SOURCE: Halpern, J.H., et al. Diminished interleukin-6 response to

proinflammatory challenge in men and women after intravenous cocaine

administration. Journal of Clinical Endocrinology and Metabolism

88(3):1188-1193, 2003.

 

 

 

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Study: Two Genes Linked to Cocaine Addiction

8/10/2004

 

Researchers have discovered two mouse genes that may help to

explain how both a genetic susceptibility and environmental factors can lead

to addiction, Health Day News reported Aug. 4.

 

For the study, researchers examined the effects of caffeine,

cocaine, and heroin on mice. The scientists identified two related genes

that control signaling between brain cells. When either of the two genes was

deleted, the mice exhibited symptoms similar to cocaine withdrawal.

 

However, the same behavioral responses were not seen when the

mice were given caffeine or heroin.

 

The study's findings are published in the Aug. 5 issue of

Neuron.

 

 

 

Szumlinski, K., et al. (2004) Homer Proteins Regulate

Sensitivity to Cocaine. Neuron, 43(3): 401-413.

 

More News Summaries

 

 

 

Study Says Marijuana Alters Blood Flow in Brain

2/9/2005

 

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Marijuana users' problems with memory and concentration could be

related to altered blood flow to the brain, according to new research from

the National Institute on Drug Abuse.

 

The BBC reported Feb. 8 that long-term marijuana smokers could

be risking memory damage and stroke because the drug appears to speed up

blood flow in the brain, possibly because it causes abnormalities in small

blood vessels. Marijuana use may narrow blood vessels, researchers said, and

the effects linger even when users abstain for a month.

 

" In the long-term one might see cognitive difficulties, such as

problems with memory and thinking, " said lead researcher Dr. Ronald Herning.

 

The study looked at 54 marijuana users who smoked between two

and 350 joints per week, as well as 18 nonsmokers. " Moderate " users -- those

consuming 70 joints per week -- showed signs of normalizing blood flow after

a month of abstinence. But " heavy " users -- those smoking up to 350 joints a

week -- showed no improvement after a month of not smoking.

 

The research was published in the Feb. 8, 2005 issue of the

journal Neurology.

 

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Survey: Sexually Active Teens More Likely to Use Drugs

8/23/2004

 

A survey of U.S. teens finds that those who are sexually active are more

likely to have tried marijuana, alcohol, and cigarettes, the Associated

Press reported Aug. 19.

 

The annual survey by the National Center on Addiction and Substance Abuse at

Columbia University polled adolescents aged 12-17 about their use of drugs

and other activities in their daily lives.

 

According to the study, 66 percent of teens who were sexually active

reported having tried alcohol, compared with 10 percent of teens who didn't

report having sex. In addition, 45 percent of teens reporting having sex

were more likely to have tried marijuana, compared with 2 percent of those

who were not sexually active. Cigarette smoking was seen in 45 percent of

sexually active teens, compared with 8 percent who abstained from teen sex.

 

" This year's survey reveals a tight connection between teen sexual behavior

and substance abuse, " said Joseph Califano Jr., president of the National

Center on Addiction and Substance Abuse. " Parents who become aware of

certain dating and sexual behavior by their children should be alert to the

increased likelihood of substance abuse. "

 

The telephone survey involved 1,000 teenagers and was conducted between

April 16 and May 16, 2004.