Biology a factor in why we get hooked, doc says
The Aspen Times
Genetics, mental illness and changes that occur in the brain all can be factors in why some people get addicted to drugs and alcohol, a top national researcher said in an Aspen Institute Spotlight Health seminar Saturday.
There is a common belief that people become addicted to something because they enjoy the feeling they get from it, but the biological process of losing control over one’s behavior is more complex than that, said Dr. Nora D. Volkow, the director of the National Institute on Drug Abuse, in a session titled “The Biology of Addiction — Why Do We Get Hooked?”
Rewards motivate humans to take certain actions, which is a crucial aspect of our biology because it includes behaviors such as eating and sex, Volkow said. But early in her research on addiction, Volkow questioned why someone would become so addicted to a pleasurable experience that they would lose their control over the behavior and choose it despite “catastrophic consequences.”
Abusing drugs creates a pleasurable feeling by increasing levels of the neurotransmitter dopamine in the reward centers of the brain. Studying cocaine abuse by using methylphenidate, a safer drug that has similar effects when injected, Volkow found that the brains of addicts had less than half the pleasurable response to the drug that non-addicts did.
Volkow followed that by monitoring the reactions of a control group and addicts to images of people using drugs and paraphernalia. Addicts would get a craving when they saw the images, causing the dopamine levels in their brain to rise, but then if they consumed, the pleasurable response did not occur.
“They’re not more sensitive to the rewarding effect but conditioned to it,” Volkow said.
Research also has shown that receptors to dopamine are fewer in the brains of addicts. Activity in the frontal cortex, which helps with decision making and self-control, is compromised as well. Those phenomena can occur due to pre-existing conditions such as genetics and mental illness, but they also can occur as a result of changes in the brain due to substance abuse or a combination of factors.
“No one chooses to be an addict,” Volkow said. “Their brains have been rewired in such a way to lead to an automatic response when they are in an environment (where the substance is available).”
Volkow believes treatment for addiction should take a multi-pronged approach of helping patients enhance their self-control, disrupt positive memories of past pleasurable experiences with substances and find other motivators that create positive reinforcement.
“Addiction can be prevented or treated, but we’re not doing either one,” Volkow said, although later she said that she should have added “sufficiently,” as the country has made great strides in combating tobacco addiction and some of the negative consequences of alcohol abuse, such as accidents and drinking among teens.
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