Chapter 4. The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
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Tom Goldman Voters in seven more states said "yes" to marijuana this month. Pot now is legal for recreational or medicinal use in more than half the country. It's still against federal law and classified as a Schedule 1 drug, meaning U.S. officials consider marijuana to have a high risk of abuse or harm, and no accepted medical use in treatment. Also, it's still banned in professional sports. Many athletes hope that will change as momentum grows nationwide for legalization. That's especially true in the National Football League, where pain is a constant companion. Advocates say marijuana could offer a safer and better way to manage the pain. Football hurts. As a fan watching from home, that's not always obvious — players collide, fall down, pop back up. They rarely wince or show weakness. That's just not how it's done in football. Kyle Turley hurt plenty during his eight NFL seasons in the 1990s and 2000s. As an offensive lineman, he was involved in jarring collisions nearly every play when his team had the ball. He hurt after his career -– Turley sometimes walks with a cane. And in a recent video, he displayed one by one the bottles of powerful painkillers he used. "Vicodin, Flexeril, Percocets, Vioxx, morphine," Turley recited as he plopped the bottles down on a kitchen counter. © 2016 npr
Sara Reardon Lasers shone into the brains of mice can now activate individual neurons — and change the animals behaviour. Scientists have used the technique to increase how fast mice drink a milkshake, but it could also help researchers to map brain functions at a much finer scale than is currently possible. Neuroscientists at Stanford University in California conducted their experiments on mice that were genetically engineered to have light-sensitive neurons in a brain region called the orbitofrontal cortex. That area is involved in perceiving, and reacting to, rewards. By shining a laser at specific neurons, the researchers increased the pace at which the mice consumed a high-calorie milkshake. The results, reported on 12 November at the annual meeting of the Society for Neuroscience in San Diego, California, illustrate for the first time that the technique, known as optogenetics, can control behaviour by activating a sequence of individual cells. One goal of optogenetics is to create automated systems that manipulate the brain on the fly using only light, says Michael Häusser, a neuroscientist at University College London, UK. This might be done by engineering neurons to contain one protein that makes the cell fire when activated by a flash of coloured light, and another that causes the cell to flash in a different colour when it fires. A device that detected this second colour could quickly determine sites of activity associated with certain behaviours and customize which cells the first light would stimulate in response. Such a system might be able to alter the neural processes that link alcohol with reward in addiction, or a visual trigger with flashbacks in post-traumatic stress disorder. © 2016 Macmillan Publishers Limited,
By Greg Miller In the mid-19th century, some European doctors became fascinated with a plant-derived drug recently imported from India. Cannabis had been used as medicine for millennia in Asia, and physicians were keen to try it with their patients. No less an authority than Sir John Russell Reynolds, the house physician to Queen Victoria and later president of the Royal College of Physicians in London, extolled the medical virtues of cannabis in The Lancet in 1890. “In almost all painful maladies I have found Indian hemp by far the most useful of drugs,” Reynolds wrote. Like other doctors of his day, Reynolds thought cannabis might help reduce the need for opium-based painkillers, with their potential for abuse and overdose. “The bane of many opiates and sedatives is this, that the relief of the moment, the hour, or the day, is purchased at the expense of to-morrow’s misery,” he wrote. “In no one case to which I have administered Indian hemp, have I witnessed any such results.” More than 125 years later, the misery caused by opioids is clearer than ever, and there are new hints that cannabis could be a viable alternative. Some clinical studies suggest that the plant may have medical value, especially for difficult-to-treat pain conditions. The liberalization of marijuana laws in the United States has also allowed researchers to compare overdoses from painkiller prescriptions and opioids in states that permit medical marijuana versus those that don’t. Yet following up on those hints isn’t easy. Clinical studies face additional hurdles because the plant is listed on Schedule I, the U.S. Drug Enforcement Administration’s (DEA’s) list of the most dangerous drugs. © 2016 American Association for the Advancement of Science.
Keyword: Drug Abuse
Link ID: 22832 - Posted: 11.04.2016
Ian Sample Science editor The devastating impact of cigarette smoke on the body’s DNA has been laid bare by the first comprehensive study into the damage tobacco inflicts on human cells. People who smoke a pack of cigarettes each day for a year develop on average 150 extra mutations in every lung cell, and nearly 100 more mutations than usual in each cell of the voice box, researchers found. More still build up in the mouth, bladder, liver and other organs. While chemicals in tobacco smoke have long been known to raise the risk of at least 17 forms of cancer, the precise molecular mechanisms through which they mutate DNA and give rise to tumours in different tissues have never been clear. “This is about running down the root cause of cancers,” said David Phillips, a professor of environmental carcinogenesis at King’s College London and a co-author on the study. “By identifying the root causes, we gain the sort of knowledge we need to think more seriously about cancer prevention.” More than 70 of the 7,000 chemicals found in tobacco smoke are known to cause cancer. Some damage DNA directly, but others ramp up mutations in more subtle ways, often by disrupting the way cells function. The more mutations a cell acquires, the more likely it is to turn cancerous. © 2016 Guardian News and Media Limited
Keyword: Drug Abuse
Link ID: 22828 - Posted: 11.04.2016
By SABRINA TAVERNISE WASHINGTON — A decade after electronic cigarettes were introduced in the United States, use has flattened, sales have slowed and, this fall, NJoy, once one of the country’s biggest e-cigarette manufacturers, filed for bankruptcy. It is quite a reversal for an invention once billed as the biggest chance to end smoking as we know it and take aim at the country’s largest cause of preventable death. Use of the devices is slumping because they are not as good as cigarettes at giving a hit of nicotine. Dealing another strike against them, the country’s top public health authorities have sent an unwavering message: Vaping is dangerous. The warning is meant to stop people who have never smoked — particularly children — from starting to vape. But a growing number of scientists and policy makers say the relentless portrayal of e-cigarettes as a public health menace, however well intentioned, is a profound disservice to the 40 million American smokers who could benefit from the devices. Smoking kills more than 480,000 Americans a year. “We may well have missed, or are missing, the greatest opportunity in a century,” said David B. Abrams, senior scientist at the Truth Initiative, an antismoking group. “The unintended consequence is more lives are going to be lost.” American public health experts, led by the Centers for Disease Control and Prevention, have long been suspicious of e-cigarettes. The possible risks of vaping are vast, officials warn, including the potential to open a dangerous new door to addiction for youth. Scientists will not know the full effect for years, so for now, they caution, be wary. But mounting evidence suggests vaping is far less dangerous than smoking, a fact that is rarely pointed out to the American public. Britain, a country with about the same share of smokers, has come to the opposite conclusion from the United States. This year, a prestigious doctors’ organization told the public that e-cigarettes were 95 percent less harmful than cigarettes. British health officials are encouraging smokers to switch. © 2016 The New York Times Company
Keyword: Drug Abuse
Link ID: 22826 - Posted: 11.03.2016
By Laura Wright, Researchers have the clearest-ever picture of the receptor that gives humans the 'high' from marijuana, which could lead to a better understanding of how the drug affects humans. Scientists have long known that molecules from THC, the psychoactive component of marijuana, bind to and activate the receptor known as CB1. But now they know that it has a three-dimensional crystal structure. The authors of the paper, which was published Thursday in the journal Cell, say this information is crucial to improve our understanding of this receptor as marijuana use becomes widespread and, in many places, legalized. Now that they know the shape of the receptor, they can get a better idea of how different molecules bind to it, which is what causes reactions in humans. "What is important is to understand how different molecules bind to the receptor, how they control the receptor function, and how this can affect different people," said Raymond Stevens, co-author of the study. Dr. Mark Ware, the executive director of the Canadian Consortium for the Investigation of Cannabinoids and the director of clinical research at the Alan Edwards pain management unit at the McGill University Health Centre, called the discovery a "breakthrough." "Suddenly we've been given the design of the building," he explained. "We can work out ways to get in the building, we know where the windows and doors and stairs are, and we know kind of how the building is structured now." They both said that knowing the receptor's design can lead to better drug design. K2 synthetic pot It's also a key step to understanding the differences between natural cannabinoids, found in the marijuana plant, and synthetic cannabinoids, made in labs. ©2016 CBC/Radio-Canada.
Keyword: Drug Abuse
Link ID: 22776 - Posted: 10.22.2016
By DONNA DE LA CRUZ Some of the most troubling images of the opioid crisis involve parents buying or using drugs with their children in tow. Now new research offers a glimpse into the addicted brain, finding that the drugs appear to blunt a person’s natural parenting instincts. Researchers at the Perelman School of Medicine at the University of Pennsylvania scanned the brains of 47 men and women before and after they underwent treatment for opioid dependence. While in the scanner, the study subjects looked at various images of babies, and the researchers measured the brain’s response. The brain scans were compared with the responses of 25 healthy people. What the study subjects didn’t know was that the photos had been manipulated to adjust the “baby schema,” the term used to describe the set of facial and other features like round faces and big eyes that make our brains register babies as irresistible, kicking in our instinct to care for them. Sometimes the babies’ features were exaggerated to make them even more adorable; in others, the chubby cheeks and big eyes were reduced, making the faces less appealing. Studies show that a higher baby schema activates the part of the brain called the ventral striatum, a key component of the brain reward pathway. Compared with the brains of healthy people, the brains of people with opioid dependence didn’t produce strong responses to the cute baby pictures. But once the opioid-dependent people received a drug called naltrexone, which blocks the effects of opioids, their brains produced a more normal response. “When the participants were given an opioid blocker, their baby schema became more similar to that of healthy people,” said Dr. Daniel D. Langleben, one of the researchers. “The data also raised in question whether opioid medications may affect social cognition in general.” © 2016 The New York Times Company
Lauren Silverman It's been a wild ride for kratom lately. Since Aug. 31, when the Drug Enforcement Administration announced its intention to classify the plant as a Schedule I substance, a group of kratom vendors filed a lawsuit against the government to block the move, angry advocates took to social media in protest and scientists questioned whether they would be able to continue kratom research. Now, the DEA is withdrawing its notice of intent to put kratom in the most restrictive category of controlled substances, with drugs like LSD and heroin. The DEA says it will instead open an official public comment period — to last until Dec. 1, 2016 — for people to share their experiences using kratom as a medical treatment. It has also requested that the Food and Drug Administration expedite scientific research. DEA spokesman Russ Baer says the DEA received more than 2,000 phone calls since August, mostly in opposition to the plan to classify kratom as Schedule I. "So in a spirit of transparency, and to open this up to public dialogue, we withdrew our notice to temporarily schedule kratom," Baer says. "We will then give full consideration to those comments before we move forward with any action." Kratom is derived from the leaves of a tree native to Southeast Asia. It is a relative of the coffee plant. According to David Kroll, a pharmacologist and medical writer, farmers and indigenous people have used it for hundreds of years as both a stimulant to increase work output and also as a way to relax. © 2016 npr
Keyword: Drug Abuse
Link ID: 22752 - Posted: 10.13.2016
By MIKE IVES HONG KONG — President Rodrigo Duterte of the Philippines was elected in May after pledging to kill 100,000 criminals in his first six months in office, vowing that fish in Manila, the capital, would grow fat from eating the bodies of drug dealers and other “do nothings.” In Mr. Duterte’s first three months as president, his bloody campaign led to the killing of about 1,400 drug suspects by the police and hundreds of others by extrajudicial means, according to official estimates. He has also publicly accused thousands of government officials of being involved in the drug trade, in some cases offering no evidence. The campaign has taken particular aim at people who use or sell shabu, a cheap form of methamphetamine that has caused grave health and social problems across the country. Mr. Duterte has likened shabu addicts to zombies and claimed — absent evidence — that many are “no longer viable for rehabilitation” because abusing the drug shrinks their brains. What is methamphetamine? Methamphetamine is an addictive stimulant that can be made from ephedrine and other readily available chemicals. It typically comes in either tablets, called yaba in parts of Asia, or crystalline form. The first variety is common in mainland Southeast Asia, and the second — known as shabu, ice or crystal meth, among other names — is more popular in the Philippines and many other countries. It also tends to be more potent and more deeply intertwined with international drug manufacturing and smuggling networks, according to a report by the United Nations Office on Drugs and Crime. How does the drug affect people who use it? Smoking, snorting, ingesting or injecting methamphetamine can cause aggression, memory loss and a range of other health complications, including heart attack or sudden death. Links between methamphetamine abuse and crime, disease transmission and other social problems have also been documented. A study by the RAND Corporation found that the effects of methamphetamine abuse, including the burden of addiction and treatment, cost the United States $23.4 billion in 2005. © 2016 The New York Times Company
Keyword: Drug Abuse
Link ID: 22751 - Posted: 10.13.2016
By CASEY SCHWARTZ Have you ever been to Enfield? I had never even heard of it until I was 23 and living in London for graduate school. One afternoon, I received notification that a package whose arrival I had been anticipating for days had been bogged down in customs and was now in a FedEx warehouse in Enfield, an unremarkable London suburb. I was outside my flat within minutes of receiving this news and on the train to Enfield within the hour, staring through the window at the gray sky. The package in question, sent from Los Angeles, contained my monthly supply of Adderall. Adderall, the brand name for a mixture of amphetamine salts, is more strictly regulated in Britain than in the United States, where, the year before, in 2005, I became one of the millions of Americans to be prescribed a stimulant medication. The train to Enfield was hardly the greatest extreme to which I would go during the decade I was entangled with Adderall. I would open other people’s medicine cabinets, root through trash cans where I had previously disposed of pills, write friends’ college essays for barter. Once, while living in New Hampshire, I skipped a day of work to drive three hours each way to the health clinic where my prescription was still on file. Never was I more resourceful or unswerving than when I was devising ways to secure more Adderall. Adderall is prescribed to treat Attention Deficit Hyperactivity Disorder, a neurobehavioral condition marked by inattention, hyperactivity and impulsivity that was first included in the D.S.M. in 1987 and predominantly seen in children. That condition, which has also been called Attention Deficit Disorder, has been increasingly diagnosed over recent decades: In the 1990s, an estimated 3 to 5 percent of school-age American children were believed to have A.D.H.D., according to the Centers for Disease Control and Prevention; by 2013, that figure was 11 percent. It continues to rise. And the increase in diagnoses has been followed by an increase in prescriptions. In 1990, 600,000 children were on stimulants, usually Ritalin, an older medication that often had to be taken multiple times a day. By 2013, 3.5 million children were on stimulants, and in many cases, the Ritalin had been replaced by Adderall, officially brought to market in 1996 as the new, upgraded choice for A.D.H.D. — more effective, longer lasting. © 2016 The New York Times Company
By Gareth Cook According to the American Psychiatric Association, about 5 percent of American children suffer from Attention Deficit Hyperactivity Disorder (ADHD), yet the diagnosis is given to some 15 percent of American children, many of whom are placed on powerful drugs with lifelong consequences. This is the central fact of the journalist Alan Schwarz’s new book, ADHD Nation. Explaining this fact—how it is that perhaps two thirds of the children diagnosed with ADHD do not actually suffer from the disorder—is the book’s central mystery. The result is a damning indictment of the pharmaceutical industry, and an alarming portrait of what is being done to children in the name of mental health. What prompted you to write this book? In 2011, having spent four years exposing the dangers of concussions in the National Football League and youth sports for The New York Times, I wanted another project. I had heard that high school students in my native Westchester County (just north of New York City) were snorting Adderall before the S.A.T.'s to focus during the test. I was horrified and wanted to learn more. I saw it not as a "child psychiatry" story, and not as a "drug abuse" story, but one about academic pressure and the demands our children feel they're under. When I looked deeper, it was obvious that our nationwide system of ADHD treatment was completely scattershot—basically, many doctors were merely prescribing with little thought into whether a kid really had ADHD or not, and then the pills would be bought and sold among students who had no idea what they were messing with. I asked the ADHD and child-psychiatry establishment about this, and they denied it was happening. They denied that there were many false diagnoses. They denied that teenagers were buying and selling pills. They denied that the national diagnosis rates reported by the C.D.C.—then 9.5 percent of children aged 4-17, now 11 percent and still growing—were valid. They basically denied that anything about their world was malfunctioning at all. In the end, they doth protest too much. I wrote about 10 front-page stories for The New York Times on the subject from 2012-2014. © 2016 Scientific American,
Ben Allen Louis Casanova is playing cards with a friend on the back deck of a recovery house in Philadelphia's northern suburbs. He's warm and open as he talks about his past few years. The guy everyone calls Louie started using drugs like Xanax and Valium during his freshman year of high school. At age 18, Casanova turned to heroin. About two years later, the rehab shuffle began. "I relapsed and then I was just getting high. And then I went to treatment again in February of 2015," he says. "Then I relapsed again and went back to treatment." He's 23 now. He's hurt people close to him and his criminal record, fueled by his drug addiction, is long. By Louie's count, he has been through eight inpatient rehabs. Louis says his stays have ranged from about 18 to 45 days. "I did 30 days, and after that I came here," he concludes, talking about his latest visit. A month's stay can be pretty typical among people who go to an inpatient facility. But why? "As far as I know, there's nothing magical about 28 days," says Kimberly Johnson, director of the Center for Substance Abuse Treatment at SAMHSA, the federal agency that studies treatment services. Anne Fletcher, author of the book Inside Rehab, agrees. "It certainly is not scientifically based," she says. "I live in Minnesota where the model was developed and a lot of treatment across the country really stemmed from that." She says the late Daniel Anderson was one of the primary architects of the "Minnesota model," which became the prevailing treatment protocol for addiction specialists. At a state hospital in Minnesota in the 1950s, Anderson saw alcoholics living in locked wards, leaving only to be put to work on a farm. © 2016 npr
Keyword: Drug Abuse
Link ID: 22719 - Posted: 10.02.2016
By MAIA SZALAVITZ Drug education is the only part of the middle school curriculum I remember — perhaps because it backfired so spectacularly. Before reaching today’s legal drinking age, I was shooting cocaine and heroin. I’ve since recovered from my addiction, and researchers now are trying to develop innovative prevention programs to help children at risk take a different road than I did. Developing a public antidrug program that really works has not been easy. Many of us grew up with antidrug programs like D.A.R.E. or the Nancy Reagan-inspired antidrug campaign “Just Say No.” But research shows those programs and others like them that depend on education and scare tactics were largely ineffective and did little to curb drug use by children at highest risk. But now a new antidrug program tested in Europe, Australia and Canada is showing promise. Called Preventure, the program, developed by Patricia Conrod, a professor of psychiatry at the University of Montreal, recognizes how a child’s temperament drives his or her risk for drug use — and that different traits create different pathways to addiction. Early trials show that personality testing can identify 90 percent of the highest risk children, targeting risky traits before they cause problems. Recognizing that most teenagers who try alcohol, cocaine, opioids or methamphetamine do not become addicted, they focus on what’s different about the minority who do. © 2016 The New York Times Company
Keyword: Drug Abuse
Link ID: 22715 - Posted: 09.30.2016
By Carl Hart In early August the Drug Enforcement Administration declined to reclassify marijuana under the federal Controlled Substances Act. The drug is currently listed on Schedule I, meaning that it is viewed as having “no currently accepted medical use in treatment” and is therefore technically banned by federal law. The proposed change would have moved it to Schedule II, where it would join morphine, opium and codeine. That would make marijuana potentially available by prescription nationwide. Such a change would have been good for patients and scientists, and it would have represented a big step toward resolving the hypocritical mess that characterizes current law. Despite many people's assumptions to the contrary, the existing law does not ban scientific investigation into the harms and benefits of the drug. It's true that scientists studying marijuana must jump through multiple bureaucratic and regulatory hoops, and one of these just became a bit easier to navigate. Currently researchers who want to study the drug must get it from the University of Mississippi, which is the only university now permitted to grow marijuana plants for research purposes. When the DEA announced in August that it would not reschedule marijuana, it did say that it would let other institutions apply for permission to start growing the plants as well. That was a step in the right direction—but it's not enough. Despite the regulatory barriers, dozens of scientists—myself included—have been engaged in research on the harms and benefits of marijuana for decades, and the evidence shows that the drug has many helpful therapeutic uses. For example, it stimulates appetite in HIV-positive patients, which could be a lifesaver for someone suffering from AIDS wasting syndrome. It is also useful in the treatment of neuropathic pain, chronic pain, and spasticity caused by multiple sclerosis. © 2016 Scientific American
Keyword: Drug Abuse
Link ID: 22710 - Posted: 09.30.2016
By Nick Purdon, Leonardo Palleja, CBC News If you met Lisa James, chances are you'd never guess she injects herself with heroin twice a day. She's a devoted mom to her daughter Tia, 24, who has a rare neurological disorder that causes tumours to grow on her spine and brain. She comforts Tia when she's overcome with nausea. She's by her side when she visits doctors. "My relationship with my daughter is better than it's ever been," says James, 48. But James says it wasn't so long ago, her days were spent doing absolutely anything to score heroin. She used to steal hundreds of dollars' worth of meat from grocery stores and sell it on the streets. She even stole from Tia. "I took $500 out of her account and because of the lovely girl that she is, she never wanted to make me feel bad," James says. "If someone had told me I would do something so despicable — I never would have believed it." She says that all changed when she was accepted to the Providence Crosstown Clinic in Vancouver's Downtown Eastside, where she's buzzed in every morning at 9 a.m. She sits down in a sterile room and injects a syringe full of free heroin into her arm. ©2016 CBC/Radio-Canada.
Keyword: Drug Abuse
Link ID: 22702 - Posted: 09.28.2016
Emma Yasinski Two often-overlooked medications might help millions of Americans who abuse alcohol to quit drinking or cut back. Public health officials, building on a push to treat people who abuse opioids with medications, want physicians to consider using medications to treat alcohol addiction. The drugs can be used in addition to or sometimes in place of peer-support programs, they say. "We want people to understand we think AA is wonderful, but there are other options," says George Koob, director of the National Institute of Alcohol Abuse and Alcoholism, a part of the federal National Institutes of Health. It is still rare for a person struggling with alcohol to hear that medication therapy exists. This partly reflects the tradition of treating addiction through 12-step programs. It's also a byproduct of limited promotion by the drugs' manufacturers and confusion among doctors about how to use them. A key study funded by the federal government reported last year that only 20 percent people who abuse alcohol will ever receive any form of treatment, which ranges from seeing a counselor or doctor to entering a specialized treatment program. The same is true for opioid addiction — about 80 percent of people dependent on opioids will never receive treatment. © 2016 npr
Keyword: Drug Abuse
Link ID: 22698 - Posted: 09.27.2016
By NICHOLAS BAKALAR Ants, like people and rats, can become addicted to morphine. Scientists divided 90 ants into three groups. The first received a solution containing morphine and sugar, which was gradually reduced until the ants were receiving pure morphine. The second group of ants got a sugar solution gradually reduced to pure water, and the third ate just sugar. Then the researchers offered all three groups the choice of sugar or morphine. The ants that had been gradually deprived of sugar and those never exposed to morphine went right back to sugar. But about two-thirds of the ants given morphine chose it over sugar. Ants are the first nonmammal to display drug-seeking behavior, the researchers said. © 2016 The New York Times Company
Keyword: Drug Abuse
Link ID: 22697 - Posted: 09.27.2016
By MICHAEL HEDRICK My father said on numerous occasions when I was growing up that he would see other families that had problems like divorce and drug use, and he would thank God that his family was so perfect. Things would change, though. They always do. And that perfect family would face just as much struggle as any other. Growing up in the mountains above Boulder, Colo., our life was good. My parents had left their life in Chicago behind for an ideal they saw in a piece of art they found at a flea market, a haphazardly painted picture of a cabin next to a river with the mountains towering in the background. Born in the early ‘80s, my brothers and I shared a bond as best friends in our small neighborhood, isolated from town, where we spent time outside sledding, building forts and making dams in the ditch that ran by our house. The biggest problems we seemed to face were bloody knees and the occasional broken bone from snowboarding and bike accidents. My dad, a subscriber to “Mother Earth News,” relished our family’s home in the mountains. There were backpacking trips to the national park 30 miles away, where he taught us how to build a fire and to hang our food from tree limbs to keep it out of reach of bears. Other times he would take us on long father-son road trips, where we would drive the long highways with nothing to look at but the passing fields and nothing to pay attention to but the books on tape from Focus on the Family that my father put on the car stereo. Those tapes provided a Christian look at what it meant to be a man, covering issues like lust, sex and puberty, and he’d answer our questions about girls and all manner of things relating to our growing into healthy young men. © 2016 The New York Times Company
By Mallory Locklear Men and women show different patterns of drug abuse, with women becoming addicted to some substances much more quickly. Now a study in rats has found that sex hormones can reduce opioid abuse. From studies of other drugs, such as cocaine and alcohol, we know that women are less likely to use these substances than men, but become addicted faster when they do. “There are a lot of data to indicate that women transition from that initial use to having a substance-use disorder much more rapidly,” says Mark Smith, a psychologist at Davidson College, North Carolina. Once addicted, women also seem to have stronger drug cravings. Tracking drug use throughout women’s menstrual cycles suggests that both these differences could be shaped by hormones – with more intense cravings and greater euphoria at particular times in the cycle, says Smith. Craving crash Now Smith’s team has investigated the effects of hormones on opioid addiction in rats. Their findings suggest that hormones such as oestrogen and progesterone may help women to kick the habit. The researchers allowed female rats to self-administer heroin, and measured how much they chose to take at different times in their oestrous cycle – a regular sequence of hormone fluctuations similar to those seen in the menstrual cycle in women. © Copyright Reed Business Information Ltd.
By Andy Coghlan You made a choice and it didn’t turn out too well. How will your brain ensure you do better next time? It seems there’s a hub in the brain that doles out rewards and punishments to reinforce vital survival skills. “Imagine you go to a restaurant hoping to have a good dinner,” says Bo Li of Cold Spring Harbor Laboratory in New York. “If the food exceeds your expectations, you will likely come back again, whereas you will avoid it in future if the food disappoints.” Li’s team has discovered that a part of the brain’s basal ganglia area, called the habenula-projecting globus pallidus (GPh), plays a crucial role in this process. They trained mice to associate specific sound cues either with a reward of a drink of water or a punishment of a puff of air in the face, and then surprised them by switching them around. When mice expecting a drink were instead punished with a puff of air, GPh neurons became particularly active. But when the mice were unexpectedly rewarded, the activity of these neurons was inhibited. Further experiments revealed that once activated GPh neurons enforce punishment in the brain, reducing levels of the reward chemical dopamine in regions of the brain that plan actions. © Copyright Reed Business Information Ltd.
Keyword: Drug Abuse
Link ID: 22681 - Posted: 09.22.2016