ahlam1399
08-11-2016, 01:44 PM
LUBECK: The brain makes less dopamine, a chemical involved in both pleasure and addiction, when people ***** but this temporary deficit may be reversed when *****rs kick the habit, a small experiment suggests.
“It is assumed that the brain adapts to the repeated nicotine-induced release of dopamine by producing less dopamine,” said lead study author Dr. Lena Rademacher of Lubeck University in Germany.
It’s still **t clear if dopamine production reduced by long-term smoking bounces back in ex-*****rs, so the researchers did brain scans of 15 never-*****rs and 30 *****rs.
Then, they offered cessation treatment to the *****rs and did a**ther set of brain scans three months later on the subset of 15 people in this group who had quit.
On the first set of scans, *****rs had a 15 percent to 20 percent lower capacity for dopamine production than the **n*****rs, researchers report in the journal Biological Psychiatry.
But in the second set of scans, there was ** longer a difference between **n*****rs and the *****rs who successfully quit during the study.
This is important because some researchers think certain people could possess naturally low dopamine production that predisposes them to addiction.
Nicotine addiction is k**wn to be associated with ab**rmalities in the dopamine system. But scientists are uncertain if smoking induces those ab**rmalities or if they already exist in some people and make them more vulnerable to getting hooked on nicotine.
Because the study found that most nicotine ab**rmalities went away after *****rs quit, it suggests they are a byproduct of smoking, Rademacher said.
“In case of a predisposing trait, ab**rmalities are expected to persist with abstinence,” Rademacher said. “Conversely, if dopamine function **rmalizes with abstinence this rather indicates that alterations were induced by substance consumption.”
One limitation of the study is its small size, which makes it difficult to draw statistically meaningful conclusions, the authors **te. The study also only included men, making it hard to say whether the findings would apply to women.
Even so, the results are encouraging because they suggest that brain function is plastic, or modifiable, and that an ex-*****r's brain can return to more **rmal functioning over time, said Joseph McCler**n, a psychiatry researcher at Duke University School of Medicine in Durham, **rth Carolina, who wasn’t involved in the study.
The findings also may have implications beyond just addiction to cigarettes because the dopamine system is involved in a broad range of functions including learning, motivation and behavior control, McCler**n added by email.
“To the extent that smoking or other drug use alters how this system functions **rmally can have impacts on behavior that increase the likelihood that one continues to use ***** or has difficulty in quitting drug use,” McCler**n said.
“Dopamine regulation of motivation for instance, is likely involved in the tendency of drug users to be overly preoccupied with drug use” to the exclusion of other forces in their lives like work and relationships, McCler**n added.
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“It is assumed that the brain adapts to the repeated nicotine-induced release of dopamine by producing less dopamine,” said lead study author Dr. Lena Rademacher of Lubeck University in Germany.
It’s still **t clear if dopamine production reduced by long-term smoking bounces back in ex-*****rs, so the researchers did brain scans of 15 never-*****rs and 30 *****rs.
Then, they offered cessation treatment to the *****rs and did a**ther set of brain scans three months later on the subset of 15 people in this group who had quit.
On the first set of scans, *****rs had a 15 percent to 20 percent lower capacity for dopamine production than the **n*****rs, researchers report in the journal Biological Psychiatry.
But in the second set of scans, there was ** longer a difference between **n*****rs and the *****rs who successfully quit during the study.
This is important because some researchers think certain people could possess naturally low dopamine production that predisposes them to addiction.
Nicotine addiction is k**wn to be associated with ab**rmalities in the dopamine system. But scientists are uncertain if smoking induces those ab**rmalities or if they already exist in some people and make them more vulnerable to getting hooked on nicotine.
Because the study found that most nicotine ab**rmalities went away after *****rs quit, it suggests they are a byproduct of smoking, Rademacher said.
“In case of a predisposing trait, ab**rmalities are expected to persist with abstinence,” Rademacher said. “Conversely, if dopamine function **rmalizes with abstinence this rather indicates that alterations were induced by substance consumption.”
One limitation of the study is its small size, which makes it difficult to draw statistically meaningful conclusions, the authors **te. The study also only included men, making it hard to say whether the findings would apply to women.
Even so, the results are encouraging because they suggest that brain function is plastic, or modifiable, and that an ex-*****r's brain can return to more **rmal functioning over time, said Joseph McCler**n, a psychiatry researcher at Duke University School of Medicine in Durham, **rth Carolina, who wasn’t involved in the study.
The findings also may have implications beyond just addiction to cigarettes because the dopamine system is involved in a broad range of functions including learning, motivation and behavior control, McCler**n added by email.
“To the extent that smoking or other drug use alters how this system functions **rmally can have impacts on behavior that increase the likelihood that one continues to use ***** or has difficulty in quitting drug use,” McCler**n said.
“Dopamine regulation of motivation for instance, is likely involved in the tendency of drug users to be overly preoccupied with drug use” to the exclusion of other forces in their lives like work and relationships, McCler**n added.
http://feeds.feedburner.com/~r/com/YEor/~4/Oa0RK8_tDTs
أكثر... (http://feedproxy.google.com/~r/com/YEor/~3/Oa0RK8_tDTs/141766-Brain-chemical-dopamine-bounces-back-after-quitting-smoking)