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BNL Addiction Symposium

at the AAAS Annual Meeting

February 16, 2007, San Francisco, CA  Symposium Home

Dopamine's Role in Drug Craving

Author: Nora Volkow
Director, National Institute on Drug Abuse

The role of dopamine in the reinforcing effects of drugs of abuse is well recognized. However its involvement in the process of drug addiction is much less clear. In this talk we will report on a study that evaluated the brain dopamine responses in addicted subjects to the presentation of drug cues and the relationship of these changes to their subjective desire for the drug. We will compare these findings to those we had previously obtained in food-deprived subjects exposed to food cues, highlighting the differences and similarities in the responses of the dopamine system of an addicted person and that of a healthy control under conditions of food deprivation. Full abstract  

Monoamine Oxidase in Smoking: Role in Addiction and Health

Author: Joanna Fowler
Director, Center for Translational Neuroimaging,
Brookhaven National Laboratory

Cigarette smoking is associated with 450,000 deaths per year in the United States alone and new knowledge on why people smoke is crucial to develop effective smoking cessation treatments. Studies of the effects of tobacco smoking on the human brain have focused almost entirely on nicotine, the major addictive component of cigarette smoke. However, brain-imaging studies of the enzyme monoamine oxidase (MAO, an enzyme that breaks down dopamine and other neurotransmitters associated with reward and mood) have shown that smokers have reduced MAO. Moreover MAO inhibition by tobacco smoke is not caused by nicotine. Low brain MAO also may explain why the rate of smoking is so high in individuals addicted to other substances and in diseases like depression (80% smoking rate in depression vs 25% in healthy individuals). In this presentation we will describe neuroimaging studies to investigate the effect of cigarette smoking on MAO in the human brain and peripheral organs and possible implications in health and disease. Full abstract

Imaging the Causes and Consequences of Inhalant Abuse

Author: Stephen Dewey
Senior Scientist,
Brookhaven National Laboratory, Upton, NY, USA.

Inhalant abuse, also known as "huffing," is a rapidly growing health problem, particularly among young people. However, little is known about how inhaled chemicals affect the brain and body. Research using positron emission tomography (PET) reveals that fumes from a variety of household products including glue, lighters, liquid correction fluid, and other solvents commonly inhaled, or "huffed," by children and young adults go straight to some of the same brain regions stimulated by cocaine and other drugs of abuse. These chemicals, such as toluene, move very quickly to pleasure centers - then move out to other brain areas, causing damage that can make huffers lose their memory, suffer vision and motor problems, and eventually develop serious mental defects. This talk will address these findings and implications and strategies for making children more aware of the dangers of huffing, as well as promising pre-clinical results on a potential treatment for inhalant abuse. Full abstract

Methamphetamine and the Brain: A Problem of Inhibitory Control

Author: Edythe D. London
University of California, Los Angeles, CA

Methamphetamine (MA) abuse is the fastest growing drug abuse problem in the world, with amphetamines used by more people worldwide than any illicit drug besides cannabis. Still, effective treatments for MA dependence are lacking. This presentation will review the medical consequences of MA abuse, including inhibitory control deficits and the links between MA dependence, risky behavior, and the spread of HIV infection. The presentation will review how brain imaging techniques (structural and functional MRI, magnetic resonance spectroscopy, and PET) have been used to help understand brain dysfunction in individuals with MA dependence, with an emphasis on defective control mechanisms involving the prefrontal cortex and limbic system. Full abstract

The Addiction-Obesity Connection

Author: Gene-Jack Wang
Chair, Medical Department
Brookhaven National Laboratory

The mechanisms underlying pathological overeating are unknown. We used positron emission tomography (PET) to assess the involvement of brain dopamine. In normal-body-weight, fasting subjects, presentation of food that could not be consumed was associated with increases in brain dopamine, providing evidence for involvement of dopamine in non-hedonic motivational properties of food intake. In addition, in pathologically obese subjects, we found reductions in dopamine D2 receptors similar to that observed in drug-addicted subjects. We postulate that decreased levels of dopamine receptors predisposes subjects to search for reinforcers (drugs or food) as a means to temporarily compensate for decreased sensitivity of dopamine-regulated reward circuits. In obese subjects, we also found increased metabolism in the somatosensory cortex. The reduction in receptors coupled with the enhanced sensitivity to food palatability may put these subjects at risk for over-consumption of food. Full abstract  

Maternal-Fetal Drug Transfer: Implications for Drug Abuse and Therapeutics

Author: Helene Benveniste
Professor, Department of Anesthesiology,
Stony Brook University and Scientist, Medical Department, Brookhaven National Laboratory

Using positron emission tomography (PET) combined with magnetic resonance imaging ( (MRI) to track the uptake and distribution of trace amounts of cocaine and nicotine in pregnant monkeys, we have demonstrated a new way to assess the potentially damaging effects of prenatal drug exposure. We found significant differences in where and how fast drugs accumulate in maternal and fetal organs. In another series of studies we used dynamic PET to non-invasively assess the pharmacodynamic effect of clinically relevant doses of maternal cocaine use on the fetal brain, heart, and liver as well as the placenta. Our findings have significant implications not only for prenatal exposure to drugs of abuse but also for future investigations of fetal responses to therapeutic drugs such as antidepressants, analgesics, and anti-seizure medications frequently taken during pregnancy. This talk will present these results as well as implications for the treatment of drug abuse and other maternal diseases. Full abstract

Promising Approaches in the Treatment of Drug Addiction

Author: Charles O’Brien
Director, Department of Psychiatry
VA Medical Center/University of Pennsylvania

Pre clinical and human laboratory models have elucidated mechanisms involved in the pathophysiology of addiction. In brief there is evidence that the underlying "lesion" in addictive disorders is a highly reinforced memory pathway that activates the brain reward system when the individual is exposed to any cue previously associated with the drug of abuse. Activation of these brain structures produces drug craving and often leads to drug seeking. This memory effect is separate from any incidental toxic effect that may also occur as part of heavy drug exposure, but is not a critical part of the addiction phenomenon. One of the major implications of these findings is that the disorder persists long after the person has stopped using drugs and thus, relapse is highly likely. Behavioral treatments in combination with medications that have been designed to reduce the rewarding effects of the drug and the craving reflex have been developed. The approach varies according to the drug. One example of an approach developed through basic animal models is the use of an opiate receptor antagonist to block the reward from alcohol ingestion. A subcategory of alcoholics has an endogenous opioid system very sensitive to alcohol and it appears that endogenous opioids are an important part of the reward mechanism for these individuals. If opiate receptors are blocked, the reward is prevented and reduced drinking or total abstinence is the result when the patient is also engaged a behavioral treatment program. The clinical efficacy of this medication has been demonstrated in numerous randomized, controlled clinical trials and a depot preparation has recently been approved by the FDA. Numerous other examples of novel medication approaches have been developed and other new medications are in the pipeline.

Last Modified: September 14, 2007