There probably will not be a surprise that smoking a joint now and then ... you feel pretty good, the man. But many smoking marijuana over a long period may do just the opposite. The scientists found that the brain potted addicts react less strongly to the chemical dopamine, which is responsible for creating feelings of pleasure and reward. Their blunted dopamine response could leave heavy marijuana users living in a fog and not the right type.
After high-profile legalization in Colorado, Washington, and Uruguay, marijuana is increasingly available in many parts of the world. Yet scientific research on the drug has been delayed. Pot contains many different chemicals, and scientists do not fully understand how these components interact to produce unique effects of different strains. His illegal status in most of the world has also thrown barriers to research. In the US, for example, any study of marijuana requires approval from four federal agencies, including the Drug Enforcement Administration. Politics also plays a role in the search for marijuana.
One of the unanswered questions about the drug is what, exactly, he does to our brain, both during and after the high. Of particular interest to scientists is the effect of marijuana on dopamine, a key ingredient in the brain's reward system. pleasurable activities such as eating, sex, and certain medications all dopamine trigger bursts essentially say the brain, "Hey, that was great-we will do it soon."
Scientists know that drug abuse can wreak havoc on the dopamine system. Cocaine and alcohol abusers, for example, are known to produce less dopamine in their brains than people who are not addicted to these drugs. But previous studies had suggested that the same might not be true for those who abuse marijuana.
Nora Volkow, director of the National Institute on Drug Abuse in Bethesda, Maryland, decided to take a look more closely at the brains of marijuana users. For help, she and her team turned to another drug: methylphenidate (Ritalin aka), a stimulant known to increase the amount of dopamine in the brain. The researchers gave 24 methylphenidate marijuana abusers (who had smoked a median of about five joints a day, 5 days a week, for 10 years) and 24 controls.
Brain imaging revealed that the two groups have produced as much extra dopamine after taking the drug. But while the controls showed an increase in heart rate and blood pressure readings and reported feeling restless and high marijuana users do not. Their responses were so weak that Volkow had to double check that methylphenidate, she gave them has not passed its expiry date.
This lack of physical response suggests that marijuana users may have damaged the reward circuits in their brains, Volkow and her report online today in the team Academy Acts national science . Unlike cocaine and alcohol abusers, marijuana users seem to produce the same amount of dopamine that people who abuse drugs. But their brains do not know what to do with it. This disconnection could be "a key mechanism underlying cannabis dependence," said Raul Gonzalez, a neuropsychologist at Florida International University in Miami, who was not involved in the research. The study "suggests that cannabis users may experience less reward from other things usually find enjoyable and, contrary to popular stereotypes, they generally feel more irritable, stressed, and just plain shabby. This can contribute to the ongoing use of cannabis and climbing among these people. "
But marijuana abusers smoke a lot because they feel lousy, or they feel lousy because they smoke a lot? Volkow does not know. Not being able to unravel the cause and effect "is a limitation in a study like this," she said. Perhaps the attackers had already dopamine systems less reactive and started smoking a ton of pot to cope with their general malaise. Or marijuana abuse can be sustained is actually damaging the reward circuitry of the brain, leading to apathy and social withdrawal that marijuana abusers often experience.
Lessons for recreational users of marijuana, if any, are unclear. This study used "unconditional voluntary [s]" that "uses a lot of cannabis," said Paul Stokes, a psychiatrist at Imperial College London who was not involved in the research. As such, "it probably tells you more about cannabis dependence on recreational use." But when he did a similar study of brain imaging of people who smoked marijuana more than once week, he observed "similar issues" when it came to dopamine.
All these questions are important to answer, said Volkow. the availability of drugs increases, she said, it is something "we all need to know."
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