Chapter 16. Psychopathology: Biological Basis of Behavior Disorders
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We all have days when we feel like our brain is going at a snail’s pace, when our neurons forgot to get out of bed. And psychologists have shown that IQ can fluctuate day to day. So if we’re in good health and don’t have a sleep deficit from last night’s shenanigans to blame, what’s the explanation? Sophie von Stumm, a psychologist at Goldsmiths University, London, set about finding out. In particular, she wanted to know whether mood might explain the brain’s dimmer switch. Although it seems intuitively obvious that feeling low could compromise intellectual performance, von Stumm says research to date has been inconclusive, with some studies finding an effect and others not. “On bad mood days, we tend to feel that our brains are lame and work or study is particularly challenging. But scientists still don’t really know if our brains work better when we are happy compared to when we are sad.” To see if she could pin down mood’s effect on IQ more convincingly, von Stumm recruited 98 participants. Over five consecutive days they completed questionnaires to assess their mood, as well as tests to measure cognitive functions, such as short-term memory, working memory and processing speed. Surprisingly, being in a bad mood didn’t translate into worse cognitive performance. However, when people reported feeling positive, von Stumm saw a modest boost in their processing speed. © Copyright Reed Business Information Ltd.
By Amy Ellis Nutt Magnetic pulses from a device applied to the head appear to "reset" the brains of depressed patients, according to a new study from the United Kingdom. The circuitry in a part of the right prefrontal cortex is known to be too active in depressed patients, causing excessive rumination and self absorption and impaired attention. When the TMS was applied to healthy subjects in this study, the activity in that region slowed. "We found that one session of TMS modifies the connectivity of large-scale brain networks, particularly the right anterior insula, which is a key area in depression," lead scientist Sarina Iwabuchi, told the European College of Neuropsychology at a conference in Amsterdam this week. This was the first time an MRI was used to guide the TMS impulses and, at the same, time measure subtle changes in brain circuit activity. In addition, the researchers used magnetic resonance spectroscopy to analyze subjects' brain chemistry. "We also found that TMS alters concentrations of neurotransmitters. Iwabuchi said, "which are considered important for the development of depression," and which are the targets of most current antidepressant medications. Transcranial Magnetic Stimulation is the use of an electromagnetic coil to deliver small, powerful bursts of energy to targeted areas known to be involved in mood regulation. It is a painless, non-invasive treatment than involves no drugs, no IVs, or any other kind of sedation, and whose chief possible side effect is a headache. (The Food and Drug Administration approved limited use of TMS in 2008 for the treatment of depression.)
Link ID: 21352 - Posted: 08.28.2015
By Felicity Muth You might have heard of serotonin as one of the ‘happy’ hormones in humans. Indeed, mood disorders like anxiety and depression are associated with low levels of serotonin. However, this neurotransmitter also has other functions. One of the more interesting ones in humans is its role in cooperation. Lowering the serotonin levels of people increases peoples’ reactions to unfairness and makes them less cooperative. On the other hand, increasing the level of serotonin in people makes people less argumentative and more communicative and cooperative. Serotonin also plays a role in peoples’ intimate relationships, for example men and women who were fed tryptophan (necessary for serotonin production) were more likely to judge photos of couples as intimate and romantic than people who had not been fed tryptophan. Humans are of course not the only animals that form intimate relationships or cooperate with each other. One of the best examples of unrelated animals cooperating comes from cleaner fish, who form relationships with ‘clients’ (visiting reef fish) where they clean their bodies, gills and even mouths. This relationship is very cooperative: the cleaner fish would rather eat the mucus from the skin of their clients than the ectoparasites (it’s yummier, apparently), but they usually keep this particular urge under control. In return, the clients don’t eat the cleaner fish, even when they are cleaning the inside of their mouths and one might think that it would be pretty tempting just to swallow one. Of course, cleaner fish do ‘cheat’ occasionally, taking a bite from the skin of a client, making the client jolt away and probably choose not to return to that particular cleaner again. © 2015 Scientific American
Sara Reardon Some of the people who survived Hurricane Katrina lost loved ones, and many were made homeless by the storm. New Orleans still bears the scars of Hurricane Katrina, ten years later. More than 500,000 people fled when the storm hit, and many never returned. Large swathes of the city are sparsely populated, particularly in the poor neighbourhoods that suffered the most severe flood damage. Psychological scars linger, too. Many hurricane survivors continue to experience mental-health problems related to the storm, whether or not they returned to New Orleans, say researchers tracking Katrina’s psychological aftermath. Such work could ultimately aid people affected by future disasters, by identifying factors — such as lack of a social-support network and unstable environments for children — that seem to increase risk of mental-health trauma. “What’s unique about this disaster is the magnitude of it,” says Joy Osofsky, a clinical psychologist at Louisiana State University in New Orleans. Katrina, a category 3 hurricane when it made landfall on 29 August 2005, ultimately damaged an area the size of the United Kingdom. In New Orleans, it destroyed basic resources such as schools and health clinics to a degree unparalleled in recent US history. Osofsky saw the devastation and despair first hand. With their clinics flooded after the storm, she and other mental-health experts set up treatment centres for emergency responders on cruise ships docked nearby on the Mississippi River, and an emergency psychology unit at the city’s central command centre. Osofsky says that the centres treated thousands of displaced and traumatized people. © 2015 Nature Publishing Group
By Laura Sanders By tweaking a single gene, scientists have turned average mice into supersmart daredevils. The findings are preliminary but hint at therapies that may one day ease the symptoms of such disorders as Alzheimer’s disease and schizophrenia, scientists report August 14 in Neuropsychopharmacology. The altered gene provides instructions for a protein called phosphodiesterase-4B, or PDE4B, which has been implicated in schizophrenia. It’s too early to say whether PDE4B will turn out to be a useful target for drugs that treat these disorders, cautions pharmacologist Ernesto Fedele of the University of Genoa in Italy. Nonetheless, the protein certainly deserves further investigation, he says. The genetic change interfered with PDE4B’s ability to do its job breaking down a molecular messenger called cAMP. Mice designed to have this disabled form of PDE4B showed a suite of curious behaviors, including signs of smarts, says study coauthor Alexander McGirr of the University of British Columbia. Compared with normal mice, these mice more quickly learned which objects in a cage had been moved to a new location, for instance, and could better recognize a familiar mouse after 24 hours. “The system is primed and ready to learn, and it doesn’t require the same kind of input as a normal mouse,” McGirr says. These mice also spent more time than usual exploring brightly lit spaces, spots that normal mice avoid. But this devil-may-care attitude sometimes made the “smart” mice blind to risky situations. The mice were happy to spend time poking around an area that had been sprinkled with bobcat urine. “Not being afraid of cat urine is not a good thing for a mouse,” McGirr says. © Society for Science & the Public 2000 - 2015
Helen Thomson Serious mood disorders such as bipolar may be the price humans have had to pay for our intelligence and creativity. That’s according to new research which links high childhood IQ to an increased risk of experiencing manic bipolar traits in later life. Researchers examined data from a large birth cohort to identify the IQ of 1,881 individuals at age eight. These same individuals were then assessed for manic traits at the age of 22 or 23. The statements they provided were part of a checklist widely used to diagnose bipolar disorder. Each person was given a score out of 100 related to how many manic traits they had previously experienced. Individuals who scored in the top 10% of manic features had a childhood IQ almost 10 points higher than those who scored in the lowest 10%. This correlation appeared strongest for those with high verbal IQ. “Our study offers a possible explanation for how bipolar disorder may have been selected through generations,” said Daniel Smith of the University of Glasgow , who led the study. “There is something about the genetics underlying the disorder that are advantageous. One possibility is that serious disorders of mood - such as bipolar disorder - are the price that human beings have had to pay for more adaptive traits such as intelligence, creativity and verbal proficiency.” Smith emphasises that as things stand, having a high IQ is only an advantage: “A high IQ is not a clear-cut risk factor for bipolar, but perhaps the genes that confer intelligence can get expressed as illness in the context of other risk factors, such as exposure to maternal influenza in the womb or childhood sexual abuse.” © 2015 Guardian News and Media Limited
Dean Burnett Yesterday, an article in the Entrepreneurs section of the Guardian purported to reveal a “cloth cap that could help treat depression”. This claim has caused some alarm in the neuroscience and mental health fields, so it’s important to look a little more closely at what the manufacturers are actually claiming. The piece in question concerns a product from Neuroelectrics: a soft helmet containing electrodes and sensors. According to the company’s website, it can be used to monitor brain activity (electroencephalography, or EEG), or administer light electrical currents to different areas of the brain in order to treat certain neurological and psychiatric conditions (known as transcranial direct current stimulation or tDCS). While this would obviously be great news to the millions of people who deal with such conditions every day, such claims should be treated with a considerable amount of caution. The fields of science dedicated to researching and, hopefully, treating serious brain-based problems like depression, stroke, personality disorder etc. work hard to find new and inventive methods for doing so, or refining and improving existing ones. Sometimes they succeed, but probably not as often as they’d like. The problem is that when a new development occurs or a new approach is found, it doesn’t automatically mean it’s widely applicable or even effective for everyone. The brain is furiously complicated. There is no magic bullet for brain problems [Note: you shouldn’t use bullets, magic or otherwise, when dealing with the brain]. © 2015 Guardian News and Media Limited
Link ID: 21305 - Posted: 08.18.2015
By NICHOLAS BAKALAR “Insanity Treated By Electric Shock” read the headline of an article published on July 6, 1940, in The New York Times. The article described “a new method, introduced in Italy, of treating certain types of mental disorders by sending an electric shock through the brain.” It was the first time that what is now called electroconvulsive therapy, or ECT, had been mentioned in The Times. The electric shock, the article said, “is produced by a small portable electric box which was invented in Italy by Professor Ugo Cerletti of the Rome University Clinic.” Dr. S. Eugene Barrera, the principal researcher on the project, “emphasized that hope for any ‘miracle cure’ must not be pinned on the new method.” On April 29, 1941, the subject came up again, this time in an article about a scientific meeting at which a professor of psychiatry at Northwestern reported “ ‘very promising instantaneous results’ in the recently developed electric shock method of relieving schizophrenic patients of their malady.” The treatment entered clinical practice fairly quickly. In October 1941, The Times reported on the opening of several new buildings at Hillside Hospital in Queens (today called Zucker Hillside Hospital). “The hospital has pioneered in the use of insulin and metrazol, and also in the electric shock treatment, which has proved useful in shortening the average stay of patients,” the article read. Over the years, ECT has had its ups and downs in the public imagination and in the pages of The Times. In an article on Nov. 25, 1980, the reporter Dava Sobel seemed to relegate it to another age. © 2015 The New York Times Company
Link ID: 21304 - Posted: 08.18.2015
There may finally be a way to stop people progressing beyond the first signs of schizophrenia – fish oil. When people with early-stage symptoms took omega-3 supplements for three months, they had much lower rates of progression than those who did not, according to one small-scale trial. People with schizophrenia are usually diagnosed in their teens or 20s, but may experience symptoms for years beforehand, such as minor delusions or paranoid thoughts. Only about a third of people with such symptoms do go on to develop psychosis, however, and antipsychotic drugs can cause nasty side effects, so these are rarely given as a preventative. Fish oil supplements, which contain polyunsaturated fatty acids like omega-3, may be a benign alternative. These fatty acids may normally help dampen inflammation in the brain and protect neurons from damage, and lower levels in the brain have been implicated in several mental illnesses. Tests have found that people with schizophrenia have lower levels of these fatty acids in their blood cells, suggesting the same could be true for their brain cells. Fish oil supplements have been investigated as a treatment for adults with schizophrenia, but so far results have been mixed – four trials found no benefit while another four found a small reduction in symptoms. But a study that gave omega-3 fish oil pills to younger people suggests that what matters is catching the condition in time. The trial followed 81 people aged 13 to 25 with early signs of schizophrenia. Roughly half took fish oil pills and half took placebo tablets for three months. A year later, those given fish oils were less likely to have developed psychosis. © Copyright Reed Business Information Ltd.
Link ID: 21288 - Posted: 08.12.2015
By Ariana Eunjung Cha Everyone knows that a diet full of white bread, pasta and rice is bad for your waistline. Now scientists say these types of refined carbs could also impact your mind — putting post-menopausal women at higher risk for depression. In a new study published in the the American Journal of Clinical Nutrition, researchers looked at data from more than 70,000 women who participated in the National Institutes of Health's women's health initiative between 1994 and 1998. They found that the more women consumed added sugars and refined grains and the higher their score on the glycemic index (GI) — a measure of the rate carbohydrates are broken down and absorbed by the body — the more they were at risk of new-onset depression. Those who had a different sort of diet — one with more dietary fiber, whole grains, vegetables and non-juice fruits — had a decreased risk. "This suggests that dietary interventions could serve as treatments and preventive measures for depression," wrote James Gangswisch, an assistant professor of psychiatry at Columbia University Medical Center, and his co-authors. The researchers explained that refined foods trigger a hormonal response in the body to reduce blood sugar levels. That is believed to lead to the "sugar high" and subsequent "crash" some people say they feel after eating such foods. This can lead to mood changes, fatigue and other symptoms of depression.
Susanne Ahmari Some 40 million people worldwide have been diagnosed with anxiety disorders. In Anxious, Joseph LeDoux presents a rigorous, in-depth guide to the history, philosophy and scientific exploration of this widespread emotional state. An eminent neuroscientist and author of The Emotional Brain (Simon & Schuster, 1996) and The Synaptic Self (Viking, 2002), he offers a magisterial review of the role of mind and brain in the generation of both unconscious defensive responses and consciously expressed anxiety. LeDoux looks first at how our understanding of anxiety has evolved. He starts with ancient etymology (the Greek angh signified constriction) and moves on to Sigmund Freud's view of anxiety as the “root of most if not all mental maladies”, and philosopher Søren Kierkegaard's perspective on it as existential, evolving from the dread that stems from freedom of choice. He then lays out the core distinction between fear and anxiety. Fear he defines as anticipation of danger from a physically present threat (a grizzly bear in front of you); anxiety, as anticipation of an uncertain threat (potential predators roaming outside your tent). But although 'fear' and 'anxiety' are excellent descriptors of conscious feelings, LeDoux shows, they should not be used to describe the unconscious mental processes and neural circuits associated with these emotions. Instead of thinking of those processes as “fear stimuli activate a fear system to produce fear responses”, he proposes conceptualizing them as “threat stimuli elicit defense responses via activation of a defensive system”. This is a subtle distinction, and LeDoux makes an excellent case that it is an important foundation for rigorous research into the neural underpinnings of the conscious and unconscious processes that subserve anxiety. © 2015 Macmillan Publishers Limited.
Link ID: 21274 - Posted: 08.08.2015
By Kristin Leutwyler Ozelli Researchers are just now beginning to discover how different biological malfunctions can give rise to symptoms of post-traumatic stress disorder (PTSD)—insight that might one day lead to more targeted treatments. In the meantime they are also exploring the use of biomarkers—hallmark variations in hormones, genes, enzymes and brain function—to apply existing therapies more effectively. “Trauma exposure can result in enduring biological changes that depend on an individual’s life history, age, gender and a host of other factors,” says Rachel Yehuda, a neuroscientist at Mount Sinai Hospital in New York City. “We must capitalize on this heterogeneity in the service of individualizing treatment approaches rather than insisting that one size fits all.” Indeed, not all patients get well by way of the most popular forms of therapy. One widely recommended treatment, cognitive behavioral therapy (CBT), typically helps only half of the patients who try it. In 2008 Richard Bryant, a professor of psychology at the University of New South Wales in Australia, and his colleagues attempted to identify that half up front. Before CBT they took brain scans using functional MRI of 14 subjects while showing them photographs of frightening faces. Seven people—the same who later failed to improve—showed greater than normal activity in brain regions associated with experiencing fear: the amygdala and the ventral anterior cingulate cortex. In another study Bryant found that the people who did benefit from CBT began treatment with larger rostral anterior cingulate cortices. Both animal and human studies have linked this brain area to “extinction,” the psychological process by which we unlearn conditioned responses, including fear. © 2015 Scientific American
By Christian Jarrett One of the saddest things about loneliness is that it leads to what psychologists call a “negative spiral.” People who feel isolated come to dread bad social experiences and they lose faith that it’s possible to enjoy good company. The usual result, as Melissa Dahl recently noted, is more loneliness. This hardly seems adaptive, but experts say it’s because we’ve evolved to enter a self-preservation mode when we’re alone. Without the backup of friends and family, our brains become alert to threat, especially the potential danger posed by strangers. Until now, much of the evidence to support this account has come from behavioral studies. For example, when shown a video depicting a social scene, lonely people spend more time than others looking at signs of social threat, such as a person being ignored by their friends or one person turning their back on another. Unpublished work also shows that lonely people’s attention seems to be grabbed more quickly by words that pertain to social threat, such as rejected or unwanted. Now the University of Chicago’s husband-and-wife research team of Stephanie and John Cacioppo — leading authorities on the psychology and neuroscience of loneliness — have teamed up with their colleague, Stephen Balogh, to provide the first evidence that lonely people’s brains, compared to the non-lonely, are exquisitely alert to the difference between social and nonsocial threats. The finding, reported online in the journal Cortex, supports their broader theory that, for evolutionary reasons, loneliness triggers a cascade of brain-related changes that put us into a socially nervous, vigilant mode. The researchers used a loneliness questionnaire to recruit 38 very lonely people and 32 people who didn’t feel lonely (note that loneliness was defined here as the subjective feeling of isolation, as opposed to the number of friends or close relatives one has). Next, the researchers placed an electrode array of 128 sensors on each of the participants’ heads, allowing them to record the participants’ brain waves using an established technique known as electro-encephalography (EEG) that’s particularly suited to measuring brain activity changes over very short time periods. © 2015, New York Media LLC.
By Julie Scelfo This week, I wrote about the pressures college students face and the related risk for depression and suicide. The article, “Suicide on Campus and the Pressure for Perfection,” generated numerous comments, and readers also raised important questions about other aspects of mental health. Q.Your story seemed to focus on women. Do boys and men experience the same kinds of pressure? A.Yes, male college students experience the same kind of pressure and commit suicide at significantly higher rates than their female counterparts. The rate of suicide among 15 to 24-year-old males in the United States was 17.3 per 100,000 in 2013, compared with 4.5 among females of the same age, according to the Centers for Disease Control and Prevention. In fact, men of all ages are far more likely to commit suicide than women. Q.If men are more likely to commit suicide, why did the story focus on a female student? A. There is still tremendous stigma surrounding mental illness, and not everyone who experiences depression is willing to talk about it. The young woman I profiled, Kathryn DeWitt, offered a rare opportunity to hear from someone who had gone all the way down to the depths of despair but — thankfully — was still alive to talk about it (and could do so articulately). Male depression is a significant concern, and a topic I have written about in the past. More information and resources are available from The National Alliance on Mental Illness. Q.Why didn’t you talk about high rates of suicide among Asian-American students? A.While suicide among Asian-American students is a significant concern, data from the C.D.C. shows the racial/ethnic group with the highest suicide rate is actually American-Indian/Alaskan Native. According to the C.D.C, the rate of suicide in that group for 15 to 24-year-olds is 9.4 for females and a staggering 29.1 for males. Q.Are parents to blame for suicide? A. The cause of any individual suicide is complex, and it would be a mistake to assume parents are to blame if a child attempts suicide. Gregory Eels, the director of Counseling and Psychological Services at Cornell, who has worked in higher education for 20 years and says he has seen “too many” student deaths, describes it this way: “The causes of a completed suicide are never a single thing. It’s a combination of thousands of things.” © 2015 The New York Times Company
Link ID: 21266 - Posted: 08.05.2015
Richard Harris One of the frequent trials of parenthood is dealing with a picky eater. About 20 percent of children ages 2 to 6 have such a narrow idea of what they want to eat that it can make mealtime a battleground. A study published Monday in the journal Pediatrics shows that, in extreme cases, picky eating can be associated with deeper trouble, such as depression or social anxiety. The study followed a broad spectrum of children who had come to Duke University for routine medical care. Most kids dislike some foods (broccoli is a common villain), but the researchers counted a child as a severely picky eater if his or her food choices were so limited that it made meals at home difficult, and meals out all but impossible. Those extreme cases were rare — just 3 percent of all kids. But, as a group, they were twice as likely as the children who weren't picky to have a diagnosis of depression, and seven times as likely to have been diagnosed with social anxiety, according to the study. Nancy Zucker, director of the Duke Center for Eating Disorders, says parents of children who are extremely finicky may find it useful to seek help, because the kids may not simply outgrow the behavior on their own. And even if they eventually do, it can be disruptive to child and family alike in the meantime. A big question is what to do about less extreme cases, which in the Duke study made up 17 percent of all children. These children have a list of foods that they are reluctant to stray beyond. © 2015 NPR
By Nancy Szokan “This is a story of a family who made mistakes.” Thus Janet Sternburg begins her memoir of a close-knit Jewish family living in Boston. Her grandfather, Philip, was a cold, angry man who abandoned his wife and six children not long after the only son in the family, Bennie, was diagnosed as schizophrenic. As Bennie became increasingly violent and untreatable, the family — advised by a Harvard professor of psychiatry — agreed to submit him to a prefrontal lobotomy. More than a decade later, one of Bennie’s sisters, Francie, sank into a debilitating depression — relentlessly weeping, attempting suicide — and again, the solution was seen to be a lobotomy. While she was growing up, Sternburg accepted the lobotomies as her family’s normalcy. It was decades later, when she was an adult living in California, that it occurred to her to question why such terrible measures had been taken. “The years came back to me when my aunt and uncle were driven to our house” for a regular visit, she writes. As the grandmother cooked and the aunts and uncles talked and played cards, the two lobotomized siblings “sat blankly on the couch — Bennie at one end, virtually unmoving, my aunt crumpled into the far corner. . . . With the sharp return of memories came the realization that even as a child I had a slight awareness . . . that something wrong had been done.” But she also knew her relatives as good and generous people. So she set out to learn what happened, and why. “White Matter: A Memoir of Family and Medicine” is Sternburg’s tale of what she discovered, put in the context of her family’s history.
Steve Connor A computer game designed by neuroscientists has helped patients with schizophrenia to recover their ability to carry out everyday tasks that rely on having good memory, a study has found. Patients who played the game regularly for a month were four times better than non-players at remembering the kind of things that are critical for normal, day-to-day life, researchers said. The computer game was based on scientific principles that are known to “train” the brain in episodic memory, which helps people to remember events such as where they parked a car or placed a set of keys, said Professor Barbara Sahakian of Cambridge University, the lead author of the study. People recovering from schizophrenia suffer serious lapses in episodic memory which prevent them from returning to work or studying at university, so anything that can improve the ability of the brain to remember everyday events will help them to lead a normal life, Professor Sahakian said. Schizophrenia affects about one in every hundred people and results in hallucinations and delusions (Rex) Schizophrenia affects about one in every hundred people and results in hallucinations and delusions (Rex) “This kind of memory is essential for everyday learning and everything we do really both at home and at work. We have formulated an iPad game that could drive the neural circuitry behind episodic memory by stimulating the ability to remember where things were on the screen,” Professor Sahakian said. © independent.co.uk
By JULIE SCELFO Kathryn DeWitt conquered high school like a gold-medal decathlete. She ran track, represented her school at a statewide girls’ leadership program and took eight Advanced Placement tests, including one for which she independently prepared, forgoing the class. Expectations were high. Every day at 5 p.m. test scores and updated grades were posted online. Her mother would be the first to comment should her grade go down. “I would get home from track and she would say, ‘I see your grade dropped.’ I would say, ‘Mom, I think it’s a mistake.’ And she would say, ‘That’s what I thought.’ ” (The reason turned out to be typing errors. Ms. DeWitt graduated with straight A’s.) In her first two weeks on the University of Pennsylvania campus, she hustled. She joined a coed fraternity, signed up to tutor elementary school students and joined the same Christian group her parents had joined at their alma mater, Stanford. But having gained admittance off the wait list and surrounded by people with seemingly greater drive and ability, she had her first taste of self-doubt. “One friend was a world-class figure skater. Another was a winner of the Intel science competition. Everyone around me was so spectacular and so amazing and I wanted to be just as amazing as they are.” Classmates seemed to have it all together. Every morning, the administration sent out an email blast highlighting faculty and student accomplishments. Some women attended class wearing full makeup. Ms. DeWitt had acne. They talked about their fantastic internships. She was still focused on the week’s homework. Friends’ lives, as told through selfies, showed them having more fun, making more friends and going to better parties. Even the meals they posted to Instagram looked more delicious. Her confidence took another hit when she glanced at the cellphone screen of a male student sitting next to her who was texting that he would “rather jump out of a plane” than talk to his seatmate. © 2015 The New York Times Company
Steve Connor Anxiety and depression could be linked to the presence of bacteria in the intestines, scientists have found. A study on laboratory mice has shown that anxious and depressive behaviour brought on by exposure to stress in early life appears only to be triggered if microbes are present in the gut. The study, published in Nature Communications, demonstrates a clear link between gut microbiota – the microbes living naturally in the intestines – and the triggering of the behavioural signs of stress. “We have shown for the first time in an established mouse model of anxiety and depression that bacteria play a crucial role in inducing this abnormal behaviour,” said Premysl Bercik of McMaster University in Hamilton, Canada, the lead author of the study. The scientists called for further research to see if the conclusions applied to humans, and whether therapies that that target intestinal microbes can benefit patients with psychiatric disorders. Previous research on mice has indicated that gut microbes play an important role in behaviour. For instance, mice with no gut bacteria – called “germ-free” mice – are less likely to show anxiety-like behaviour than normal mice. The latest study looked at mice that had been exposed to a stressful experience in early life, such as being separated from their mothers. When these mice grow up they display anxiety and depression-like behaviour and have abnormal levels of the stress hormone corticosterone in their blood, as well as suffering from gut dysfunction based on the release of the neurotransmitter acetylcholine.
Link ID: 21232 - Posted: 07.29.2015
By C. CLAIBORNE RAY Q. Are men more likely to be claustrophobic than women? A. The opposite seems to be true, as is the case in almost all anxiety disorders, large epidemiological studies have found. The reasons for such a gender difference are not clear, and claustrophobia, the feeling of extreme panic when faced with being in a confined or enclosed space, is not as well studied as some other phobias. One situation that has been comparatively well researched is what happens when people need magnetic resonance imaging, which often involves a prolonged period of confinement in a small enclosure, the perfect storm of claustrophobia triggers. A recent study found that certain factors seem to correlate with an increase in claustrophobic reactions, including being female, going into the scanner head first and having a previous negative experience with the test. Another large study involving scanners with a shorter chamber and noise reduction found a significant reduction in claustrophobic reactions, but being female and middle-aged were still associated with a higher rate of claustrophobia. It has often been assumed that claustrophobia develops as a response to a traumatic experience, like being trapped in a closet as a child, but newer research suggests a genetic component. In one study in mice, a single defective gene was associated with claustrophobia. email@example.com © 2015 The New York Times Company