Our minds are powerful things, they grow and change, with knowledge, with experiences and habits, and our brains adapt. It’s called neuroplasticity. And it’s part of your normal development, until a foreign substance manipulates it. Scientists are learning just how dramatic the effects of opioids can be on the human brain.
“These are things we can see under the microscope,” said Ellen Unterwald, director of the Center for Substance Abuse Research at Temple University. “There are actually structural changes to neurons in different brain regions, and those are different for different drugs of abuse. They each have their own signature,” she said.
Neuroscientists like Unterwald are learning more about these changes in regards to opiate use, in hope of looking for signs of addiction before they develop. Painkillers or not, no one is truly opioid free, as opioids occur naturally. An example of which is a runners high, or the benefits of acupuncture, which produce opioids made in the brain, such as endorphins that encourage the good feelings.
Opioid linked reward circuits in the brain can even be elevated by looking at delicious food or a desired object, according to new imaging researched from Finland. Penn State just recently began studying brain imagine to track children’s responsiveness to food rewards to see how they might predict obesity. The mind tells all.
Though the desires are different, the individuals brains sense and respond to everyday pleasures could explain a range of behaviors from overeating to one’s likelihood of opioid abuse.
“Certainly more than half the risk (for opioid abuse) is genetic,” said Henry Kranzler, director of the Center for the Studies of Addiction at the University of Pennsylvania. “Risk is not about character. It’s about genetics and environmental exposure.”
Kranzler, an expert substance abuse disorders after publishing hundreds of scientific papers on the topic, calls them “genetically complex,”
“There are many different genes—we’re not even sure how many—that contribute to risk.”
During a study, Kranzler and his colleages identified a gene variant in African American children that showed a lower sensitivity to prescription pain medications. This lead them to seek more of the same, that may be in older African Americans who have had opioids after knee or hip replacements. Long-term, the goal is to customize prescription medications for patients undergoing surgery to make the pain management process less risky and more effective at the same time.
It’s euphoric effects are well understood, “The reward pathway that’s stimulated by things that we find pleasurable—eating, social interaction, sex—causes dopamine to be released. Opioids act at the beginning of that pathway,” says Unterwald.
Opioid medications like morphine can do much more than stimulate pleasure. Many opioids target the amygdala, an emotional and motivation center deep within the brain, which drives up drug cravings when aroused. This can drive up drug cravings.
As recently as June, a study published by a team of researchers from Temple University, the Max Planck Institute of Biochemistry in Germany, and the Medical University of Innsbruck in Austria used sensitive instruments to detect drug-induced molecular changes in the brains of rats.
“We found more than 1,000 changes after exposure to an opioid-like drug, showing a global effect of these drugs on signaling in the brain,” Jeffrey Liu, the lead author of the study, said in a statement.
The rats were given high doses of opioids daily, and the study found tiny structures throughout the brain called dendritic spines begin to disappear, said Wade Berrettini, director of the Center for Neurobiology and Behavior at Penn. The structures allowed neurons to communicate with one another, and in losing them, the lack of structures lead to “trouble reasoning and thinking through problems,” he said.
During addiction’s progression, the brain’s reward center becomes off centered. Cravings can become irresistible and steer behavior towards rewards instead of responsibilities. Berrettini said even simple triggers like old friends and familiar street corners can spur the urge to use again, as can general life stressors. And because of widespread brain changes including the loss of dendritic spines, those in addiction may have “limited ability to resist,” he said.
“Part of the dysregulation that occurs,” said Temple’s Unterwald, “is because the drug is onboard and then goes away. Opioid users take heroin many times a day, so (the brain) cycles through periods of highs and withdrawals.”
And the motivation to avoid opioid withdrawals, cramping, sweating, nausea and more, are the result of the brains adaptations she said.
During a first use, one of the stress-associated regions in the brain called the locus coeruleus becomes muted. Long-term exposure has the brain compensate the neurons in that region by supercharging them. Once the dampening effects are removed an altered locus coeruleus can create chaos and the painful symptoms of withdrawals set in.
Opioid effects on the brain can reverse themselves, but some take more time.
Patients given opioids for cancer related pain are typically weaned off their medications over several weeks to avoid withdrawals setting in said Unterwald, “But that’s not what usually happens with opioid abusers.”
“People who would like to be drug-free often transition to one of the medication-assisted therapies like methadone or buprenorphine,” said Unterwald, and may gradually reduce intake of these stabilizing opioids, though experts say long-term use is the gold standard for achieving long-term recovery. “These drugs are not really replacing (opioids),” she said. “They are resetting the neurobiological changes that have occurred.”
To achieve a custom effect for addiction treatment, Penn States’ Kranzler and colleagues rely on a standard scale to assess the severity of an individual’s addiction. By studying the genetic makeup of those with the highest scores, the team is discovering DNA markers associated with severe addiction.
“We are looking to identify genetic biomarkers that can be used to dose medications, both for analgesics for pain post-surgery as well as for methadone maintenance,” he said. The FDA is currently evaluating whether genetic or brain-based signatures can be used to guide clinical decision-making.
“Treatment works,” Kranzler said. “We tend to hear more about the people for whom treatment failed—and there still are too many of those. The better we can match treatment to an individual’s profile, both genetic and otherwise, the better we are going to be able to treat people.”
Source : The Recover Newsroom
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