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Scientists have new visual evidence that cocaine and amphetamine abuse produce specific structural and functional changes in the brain, according to Alan Leshner, Ph.D., director of the National Institute on Drug Abuse at a conference on drug addiction treatment in Washington, D.C. last month.
The goal of the conference was to disseminate the latest drug research treatment findings to practitioners, law enforcement and criminal justice personnel, policymakers, and the media.
Leshner continued, "We can see in the brain of an addict, just minutes after acute cocaine infusion, the positive signal changes in multiple subcortical and brainstem structures." Previous neuroimaging techniques have been limited in their ability to visualize these vital structures, Leshner observed.
"Moreover, for most abused drugs, it is the immediate dramatic upsurges in extracellular dopamine levels that account for the euphoria," he explained.
To illustrate his point, Leshner referred to an animal study showing that the dopamine level rose about six times the normal rate within 20 minutes after receiving 3 mg of cocaine. In contrast, the animal's dopamine level rose only slightly when injected with .3 mg of cocaine.
Research has shown that animals will work to produce such euphoric effects, said Leshner. For example, an animal's dopamine level rose rapidly to about seven times the normal level when it pressed a lever repeatedly to receive amphetamine.
Over the next two and a half hours, the animal pressed its lever at about 20-minute intervals. "When the animal's dopamine level fell to about 2.5 times the normal rate, the animal 'asks for more' by pressing the lever again," explained Leshner.
The prolonged use of many drugs can also produce fundamental and long-lasting changes in the brain including a reduced capacity to synthesize dopamine, he added.
Sequential positron emission tomo-graphy (PET) scans of a primate's brain showed significant swings in its dopamine levels after receiving a daily dose of amphetamine increased from 4 mg to 18 mg over 10 days.
Following the drug regimen, dopamine activity decreased by 75 percent after the first month, 50 percent at six months, and 10 percent at one year. "Two years after drug use, an apparent recovery of dopamine function was observed," said Leshner.
The director also cited NIDA's Drug Addiction Treatment Initiative, which was launched last year and has the following goals:
Leshner also announced the release of the first two therapy manuals for treating drug addiction that are part of a series of manuals whose development NIDA is funding.
The first manual, A Cognitive Behavioral Approach: Treating Cocaine Dependence, describes components of cognitive behavioral therapy (CBT) skills and treatment including integrating CBT and medication, problem solving, and case management.
The second manual, A Community Reinforcement Plus Vouchers Approach: Treating Cocaine Addiction, describes clinical approaches and voucher programs, among other topics. Vouchers, which patients turn into points that give them purchasing power, are used by treatment programs to reinforce abstinence and provide treatment motivation. The manual also describes drug-avoidance skills, relationship counseling, and other substance abuse and psychiatric problems.
The manuals can be ordered by calling (800) 729-6686 and referring to #BKD-254 for the first manual and #BKD-255 for the second manual. In May the manuals are also scheduled to be available through NIDA's Web site at www.nida.nih.gov.