More than 1,000 researchers are meeting this week in Puerto Rico at the annual College on Problems of Drug Dependence (CPDD) to discuss the latest studies on drug dependence and abuse. The international aspects of drug abuse will be discussed at a meeting convened by the National Institute on Drug Abuse (NIDA), June 16-17. The 62nd annual meeting of the CPDD will be held June 17-23 and will feature the latest news on drug dependence and abuse as it relates to adolescents, gender differences, technological advancements, and treatment.
Adolescent Drug Abuse:
Most cigarette, alcohol, and drug use begins during adolescence, and an early age of onset of drug use is associated with longer and more severe use and more difficulty achieving abstinence. Over the years, many factors have been implicated in the initiation of cigarette, alcohol, and other drug use. Researchers at this year's CPDD meeting will present data showing that parents and peers are strong influencers in adolescent drug use.
In a study comparing the rates of drug use and dependence between American and Puerto Rican adolescents 15-18 years of age, researchers L. Warner (Rutgers University) and colleagues found that while alcohol and drug abuse are higher among adolescents in the United States, youngsters in Puerto Rico had higher rates of drug dependence. The greater incidence of dependence was attributed to a higher frequency of problems with family and police, as well as emotional problems and physical illness among youth in Puerto Rico. These findings may support the development of appropriate cross-cultural substance abuse prevention programs.
Two other studies show that parents may play a key role in the prevention of substance abuse in their children. The first, a study by researchers J.J. Lloyd and J.C. Anthony of Johns Hopkins University, indicates that earlier parental supervision may influence a child's decision whether to associate with peers who use illegal substances, ultimately influencing the child's decision to use drugs.
A second study by C.S. Storr and colleagues at Johns Hopkins University indicates that a smoking prevention program implemented both at home and in the classroom is effective in improving the child's performance and conduct in elementary school by increasing the parent's instruction and behavior management skills.
A.C. Mezzich, S. Lu, and S. Parks (University of Pittsburgh) recently found that adolescent girls whose peers abuse substances are more susceptible to drug use. Furthermore, adolescents with psychiatric symptomology, sexual abuse, and poor parent-daughter relationships and association with drug-using peers predict substance severity in young adulthood.
Gender Differences:
According to researchers, gender differences play a role in drug abuse and addiction. In two studies, Dr. Kathryn Cunningham and colleagues from the University of Texas at Galveston found that the hormone estrogen increased the stimulant effects of cocaine in laboratory rats. A separate study by Dr. Wendy Lynch and colleagues from the University of
Minnesota found that estrogen increased the amount of cocaine self-administered by rodents.
Together, these findings suggest women's higher estrogen levels may result in more drug-seeking behavior, and making it harder for women in treatment programs to stop using drugs.
Another study by Dr. Marc Kaufman and colleagues at Harvard Medical School, which assessed the effects of cocaine on brain blood flow in men and women, found that cocaine constricted brain blood vessels in men, but failed to do so in women during the first part of their menstrual cycle when estrogen levels are higher. This suggests that estrogen may protect women against cocaine's vasoconstrictive effects.
Dr. L. Reneman and colleagues from the University of Amsterdam, who studied the brain blood flow patterns in men and women who were chronic users of the stimulant drug
MDMA (ecstasy), found that women experienced more brain flow disturbances than men. The implications are that women who use ecstasy may be more likely than men to develop neurologic dysfunction.
Technological Breakthroughs/Advances:
Modern technology can take advantage of new scanning procedures to see how the brain works in normal and diseased states. Measures of how fast blood flows through the different parts of the brain can point out damage or changes in function when taking a drug or medication. One technique available for this purpose is SPECT (single photon computed emission tomography) scanning, which requires the injection of a radioactive substance. In a study supported by NIDA, scientists at Yale University are taking SPECT scans of cocaine abusers to test the effects of treatment medications. The scans show improvement in blood flow in the cortex when the participants are treated either with aspirin or isradipine, a calcium channel blocker similar to other medications used to treat heart disease. The findings emphasize the deleterious effects of cocaine on the brain and the potential for improvement with medications.
New approaches using nuclear magnetic resonance (MRI) can help assess the biochemistry and activity of different parts of the brain under normal conditions, in diseases or drug-induced states. Two recent studies by investigators collaborating at the Universities of Basel (Zurich, Switzerland) and Freiburg (Germany) found that the frontal lobes in the brains of heroin-dependent participants have a reduced concentration of N-acetyl aspartate, a substance found only in nerve cells. The findings indicate a toxic effect of long-term heroin use, seen as a loss of nerve cells in the frontal lobes of heroin-dependent individuals.
At the University of Chicago, scientists using MRI to test how patterns of blood flow change when the brain is at work, found that when a person taking amphetamines is performing a task that requires sustained attention, a greater number of nerve cells are involved.
Treatment News:
One type of treatment includes chemicals that interfere with the effects that drugs of abuse have on the brain. Ethanol may exert some of its effects on the brain by acting on specialized proteins (called receptors) that also are influenced by cannabis (marijuana).
Dr. Mansbach and colleagues at Pfizer Inc. demonstrated that a newly synthesized compound (so new that it has yet to be assigned a name) that blocks the effects of cannabis at its particular receptor also decreases the amount of ethanol that mice will drink. Therefore, blocking specific cannabis receptors may help in treating alcoholism.
Other research has shown that activating or turning on a different set of brain receptors may be useful in treating alcoholism. Researchers have found that activating a specific receptor in the brain, called the kappa opioid receptor, appears to reduce the "high" or feel-good sensations of many abused drugs (including ethanol, cocaine, and PCP). Implications are that diminishing the euphoric effects of drugs may also reduce the desire to take the drug.
Studies on two medications show promise for treating the cravings and euphoria associated with cocaine use. A recent study on rats by Dr. VandenEynden and colleagues at the University of Cincinnati suggests that, depending on the dose administered, a compound that mimics particular effects of the neurotransmitter dopamine (pramixpexole) may be able to reduce the good feelings associated with using cocaine. Larger doses work to selectively reduce the craving sensations that occur after the animal no longer has access to cocaine.
A NIDA-funded study conducted by Dr. R.T. Jones and colleagues (at the University of Cincinnati, San Francisco) found that wearing a patch made of Selegiline?an monoamine oxidase inhibitor, which is a type of medication safely used to treat depression--during cocaine administrations reduced craving for the drug.
Researchers at Columbia University are studying two additional agents that may be promising. Dr. T.J. Baird and colleagues have been examining the influence of a novel cocaine antibody known as Mab 15A10 and butyryl-cholinesterase, a naturally occurring endogenous enzyme. The scientists found that administering either agent reduced cocaine self-administration in laboratory animals and they suggest that both agents should continue to be studied in the search for effective treatments for cocaine addiction.