Posts Tagged ‘anxiety’

by PETER DOCKRILL

When bad things happen, we don’t want to remember. We try to block, resist, ignore – but we should perhaps be doing the opposite, researchers say.

A new study led by scientists in Texas suggests the act of intentionally forgetting is linked to increased cerebral engagement with the unwanted information in question. In other words, to forget something, you actually need to focus on it.

“A moderate level of brain activity is critical to this forgetting mechanism,” explains psychologist Tracy Wang from the University of Texas at Austin.

“Too strong, and it will strengthen the memory; too weak, and you won’t modify it.”

Trying to actively forget unwanted memories doesn’t just help prevent your brain from getting overloaded.

It also lets people move on from painful experiences and emotions they’d rather not recall, which is part of the reason it’s an area of active interest to neuroscientists.

“We may want to discard memories that trigger maladaptive responses, such as traumatic memories, so that we can respond to new experiences in more adaptive ways,” says one of the researchers, Jarrod Lewis-Peacock.

“Decades of research has shown that we have the ability to voluntarily forget something, but how our brains do that is still being questioned.”

Much prior research on intentional forgetting has focussed on brain activity in the prefrontal cortex, and the brain’s memory centre, the hippocampus.

In the new study, the researchers monitored a different part of the brain called the ventral temporal cortex, which helps us process and categorise visual stimuli.

In an experiment with 24 healthy young adults, the participants were shown pictures of scenes and people’s faces, and were instructed to either remember or forget each image.

During the experiment, each of the participants had their brain activity monitored by functional magnetic resonance imaging (fMRI) machines.

When the researchers examined activity in the ventral temporal cortex, they found that the act of forgetting effectively uses more brain power than remembering.

“Pictures followed by a forget instruction elicited higher levels of processing in [the] ventral temporal cortex compared to those followed by a remember instruction,” the authors write in their paper.

“This boost in processing led to more forgetting, particularly for items that showed moderate (vs. weak or strong) activation.”

Of course, forgetting specific images on demand in a contrived laboratory experiment is very different to moving on from painful or traumatic memories of events experienced in the real world.

But the mechanisms at work could be the same, researchers say, and figuring out how to activate them could be a huge benefit to people around the world who need to forget things, but don’t know how.

Especially since this finding in particular challenges our natural intuition to suppress things; instead, we should involve more rather than less attention to unwanted information, in order to forget it.

“Importantly, it’s the intention to forget that increases the activation of the memory,” Wang says.

“When this activation hits the ‘moderate level’ sweet spot, that’s when it leads to later forgetting of that experience.”

The findings are reported in JNeurosci.

https://www.sciencealert.com/to-forget-something-you-need-to-think-about-it-neuroscientists-reveal

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by Carly Cassella

Sticks and stones may break your bones, but name-calling could actually change the structure of your brain.

A new study has found that persistent bullying in high school is not just psychologically traumatising, it could also cause real and lasting damage to the developing brain.

The findings are drawn from a long-term study on teenage brain development and mental health, which collected brain scans and mental health questionnaires from European teenagers between the ages of 14 and 19.

Following 682 young people in England, Ireland, France and Germany, the researchers tallied 36 in total who reported experiencing chronic bullying during these years.

When the researchers compared the bullied participants to those who had experienced less intense bullying, they noticed that their brains looked different.

Across the length of the study, in certain regions, the brains of the bullied participants appeared to have actually shrunk in size.

In particular, the pattern of shrinking was observed in two parts of the brain called the putamen and the caudate, a change oddly reminiscent of adults who have experienced early life stress, such as childhood maltreatment.

Sure enough, the researchers found that they could partly explain these changes using the relationship between extreme bullying and higher levels of general anxiety at age 19. And this was true even when controlling for other types of stress and co-morbid depressive symptoms.

The connection is further supported by previous functional MRI studies that found differences in the connectivity and activation of the caudate and putamen activation in those with anxiety.

“Although not classically considered relevant to anxiety, the importance of structural changes in the putamen and caudate to the development of anxiety most likely lies in their contribution to related behaviours such as reward sensitivity, motivation, conditioning, attention, and emotional processing,” explains lead author Erin Burke Quinlan from King’s College London.

In other words, the authors think all of this shrinking could be a mark of mental illness, or at least help explain why these 19-year-olds are experiencing such unusually high anxiety.

But while numerous past studies have already linked childhood and adolescent bullying to mental illness, this is the very first study to show that unrelenting victimisation could impact a teenager’s mental health by actually reshaping their brain.

The results are cause for worry. During adolescence, a young person’s brain is absolutely exploding with growth, expanding at an incredible place.

And even though it’s normal for the brain to prune back some of this overabundance, in the brains of those who experienced chronic bullying, the whole pruning process appears to have spiralled out of control.

The teenage years are an extremely important and formative period in a person’s life, and these sorts of significant changes do not bode well. The authors suspect that as these children age, they might even begin to experience greater shrinkage in the brain.

But an even longer long-term study will need to be done if we want to verify that hunch. In the meantime, the authors are recommending that every effort be made to limit bullying before it can cause damage to a teenager’s brain and their mental health.

This study has been published in Molecular Psychiatry.

https://www.sciencealert.com/chronic-bullying-could-actually-reshape-the-brains-of-teens

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The NIHR and King’s College London are calling for 40,000 people diagnosed with depression or anxiety to enrol online for the Genetic Links to Anxiety and Depression (GLAD) Study and join the NIHR Mental Health Bioresource.

Researchers hope to establish the largest ever database of volunteers who can be called up to take part in research exploring the genetic factors behind the two most common mental health conditions – anxiety and depression.

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The GLAD study will make important strides towards better understanding of these disorders and provide a pool of potential participants for future studies, reducing the time-consuming process of recruiting patients for research.

Research has shown 30-40% of the risk for both depression and anxiety is genetic and 60-70% due to environmental factors. Only by having a large, diverse group of people available for studies will researchers be able to determine how genetic and environmental triggers interact to cause anxiety and depression.

Leader of the GLAD study and the NIHR Mental Health BioResource, Dr Gerome Breen of King’s College London, said: “It’s a really exciting time to become involved in mental health research, particularly genetic research which has made incredible strides in recent years – we have so far identified 46 genetic links for depression and anxiety.

“By recruiting 40,000 volunteers willing to be re-contacted for research, the GLAD Study will take us further than ever before. It will allow researchers to solve the big unanswered questions, address how genes and environment act together and help develop new treatment options.”

The GLAD Study, a collaboration between the NIHR BioResource and King’s College London, has been designed to be particularly accessible, with a view to motivating more people to take part in mental health research.

Research psychologist and study lead Professor Thalia Eley, King’s College London, said: “We want to hear from all different backgrounds, cultures, ethnic groups and genders, and we are especially keen to hear from young adults. By including people from all parts of the population, what we learn will be relevant to everyone. This is a unique opportunity to participate in pioneering medical science.”

https://www.nihr.ac.uk/news/nihr-launches-largest-ever-study-of-genetic-links-to-depression-and-anxiety/9201

inhaled-version-of-blood-pressure-drug-shows-promise-in-treating-anxiety-pain-309437

An inhaled form of a high blood pressure medication has potential to treat certain types of anxiety as well as pain, according to a new study by the Centre for Addiction and Mental Health (CAMH).

Anxiety disorders are usually treated with different types of medications, such as antidepressants, and psychotherapy. Amiloride is a medication offering a new approach, as a short-acting nasal spray that could be used to prevent an anxiety attack.

“Inhaled amiloride may prove to have benefits for panic disorder, which is typically characterized by spells of shortness of breath and fear, when people feel anxiety levels rising,” says lead author Dr. Marco Battaglia, Associate Chief of Child and Youth Psychiatry and Clinician Scientist in the Campbell Family Mental Health Research Institute at CAMH.

The study was based on understanding the key physiological changes in brain functioning that are linked to anxiety and pain sensitivity. The researchers then tested a molecule, amiloride, which targets this functioning.

Amiloride was inhaled so that it could immediately access the brain. The study showed that it reduced the physical respiratory signs of anxiety and pain in a preclinical model of illness. This therapeutic effect didn’t occur when amiloride was administered in the body, as it didn’t cross the blood-brain barrier and did not reach the brain.

Results were published in the Journal of Psychopharmacology.

The role of early life adversity
The study is based on years of research into how a person’s early life experiences affect their genes, says Dr. Battaglia. Childhood adversity, such as loss or separation from parents, increases the risk of anxiety disorders and pain, among other health issues.

At a molecular level, these negative life experiences are linked to changes in some genes of the ASIC (acid-sensing-ion-channels) family. While the DNA itself doesn’t change, the way it functions is affected.

DNA is converted into working proteins through a process called gene expression. As a result of childhood adversity, some ASIC genes showed increased expression and epigenomic changes. (“Epigenomic” refers to changes in gene regulation that can inherited by children). Overlapping genetic changes were also seen in blood taken from twins who responded to specific tests designed to provoke panic.

These genetic changes are linked to physical symptoms. Breathing can be affected, due to over-sensitivity to higher carbon dioxide levels in the air. In such situations, a person might hyperventilate and experience growing anxiety. Preclinical and human data are strikingly similar in this regard. “As a treatment, amiloride turned out to be very effective preclinically,” says Dr. Battaglia.

The next step in his research is to test whether it eases anxiety symptoms. Dr. Battaglia is now launching a pilot clinical trial, supported through a seed grant from CAMH’s new Discovery Fund. Collaborators at the University of Utah are testing the drug’s safety.

Amiloride has been used as an oral treatment for decades for hypertension, and as an inhaled spray in a few experimental studies of cystic fibrosis, he notes. The researchers are therefore further ahead than if they had to develop and test an entirely new medication.

https://www.technologynetworks.com/neuroscience/news/inhaled-version-of-blood-pressure-drug-shows-promise-in-treating-anxiety-pain-309437

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A 3-D rendering of the serotonin system in the left hemisphere of the mouse brain reveals two groups of serotonin neurons in the dorsal raphe that project to either cortical regions (blue) or subcortical regions (green) while rarely crossing into the other’s domain.

As Liqun Luo was writing his introductory textbook on neuroscience in 2012, he found himself in a quandary. He needed to include a section about a vital system in the brain controlled by the chemical messenger serotonin, which has been implicated in everything from mood to movement regulation. But the research was still far from clear on what effect serotonin has on the mammalian brain.

“Scientists were reporting divergent findings,” said Luo, who is the Ann and Bill Swindells Professor in the School of Humanities and Sciences at Stanford University. “Some found that serotonin promotes pleasure. Another group said that it increases anxiety while suppressing locomotion, while others argued the opposite.”

Fast forward six years, and Luo’s team thinks it has reconciled those earlier confounding results. Using neuroanatomical methods that they invented, his group showed that the serotonin system is actually composed of at least two, and likely more, parallel subsystems that work in concert to affect the brain in different, and sometimes opposing, ways. For instance, one subsystem promotes anxiety, whereas the other promotes active coping in the face of challenges.

“The field’s understanding of the serotonin system was like the story of the blind men touching the elephant,” Luo said. “Scientists were discovering distinct functions of serotonin in the brain and attributing them to a monolithic serotonin system, which at least partly accounts for the controversy about what serotonin actually does. This study allows us to see different parts of the elephant at the same time.”

The findings, published online on August 23 in the journal Cell, could have implications for the treatment of depression and anxiety, which involves prescribing drugs such as Prozac that target the serotonin system – so-called SSRIs (selective serotonin reuptake inhibitors). However, these drugs often trigger a host of side effects, some of which are so intolerable that patients stop taking them.

“If we can target the relevant pathways of the serotonin system individually, then we may be able to eliminate the unwanted side effects and treat only the disorder,” said study first author Jing Ren, a postdoctoral fellow in Luo’s lab.

Organized projections of neurons

The Stanford scientists focused on a region of the brainstem known as the dorsal raphe, which contains the largest single concentration in the mammalian brain of neurons that all transmit signals by releasing serotonin (about 9,000).

The nerve fibers, or axons, of these dorsal raphe neurons send out a sprawling network of connections to many critical forebrain areas that carry out a host of functions, including thinking, memory, and the regulation of moods and bodily functions. By injecting viruses that infect serotonin axons in these regions, Ren and her colleagues were able to trace the connections back to their origin neurons in the dorsal raphe.

This allowed them to create a visual map of projections between the dense concentration of serotonin-releasing neurons in the brainstem to the various regions of the forebrain that they influence. The map revealed two distinct groups of serotonin-releasing neurons in the dorsal raphe, which connected to cortical and subcortical regions in the brain.

“Serotonin neurons in the dorsal raphe project to a bunch of places throughout the brain, but those bunches of places are organized,” Luo said. “That wasn’t known before.”

Two parts of the elephant

In a series of behavioral tests, the scientists also showed that serotonin neurons from the two groups can respond differently to stimuli. For example, neurons in both groups fired in response to mice receiving rewards like sips of sugar water but they showed opposite responses to punishments like mild foot shocks.

“We now understand why some scientists thought serotonin neurons are activated by punishment, while others thought it was inhibited by punishment. Both are correct – it just depends on which subtype you’re looking at,” Luo said.

What’s more, the group found that the serotonin neurons themselves were more complex than originally thought. Rather than just transmitting messages with serotonin, the cortical-projecting neurons also released a chemical messenger called glutamate – making them one of the few known examples of neurons in the brain that release two different chemicals.

“It raises the question of whether we should even be calling these serotonin neurons because neurons are named after the neurotransmitters they release,” Ren said.

Taken together, these findings indicate that the brain’s serotonin system is not made up of a homogenous population of neurons but rather many subpopulations acting in concert. Luo’s team has identified two groups, but there could be many others.

In fact, Robert Malenka, a professor and associate chair of psychiatry and behavioral sciences at Stanford’s School of Medicine, and his team recently discovered a group of serotonin neurons in the dorsal raphe that project to the nucleus accumbens, the part of the brain that promotes social behaviors.

“The two groups that we found don’t send axons to the nucleus accumbens, so this is clearly a third group,” Luo said. “We identified two parts of the elephant, but there are more parts to discover.”

https://medicalxpress.com/news/2018-08-brain-serotonin.html


Pinpoint stimulation of a cluster of nerve cells in the brains of mice encouraged timid responses to a perceived threat, whereas stimulation of an adjacent cluster induced boldness and courage.

Researchers at the Stanford University School of Medicine have identified two adjacent clusters of nerve cells in the brains of mice whose activity level upon sighting a visual threat spells the difference between a timid response and a bold or even fierce one.

Located smack-dab in the middle of the brain, these clusters, or nuclei, each send signals to a different area of the brain, igniting opposite behaviors in the face of a visual threat. By selectively altering the activation levels of the two nuclei, the investigators could dispose the mice to freeze or duck into a hiding space, or to aggressively stand their ground, when approached by a simulated predator.

People’s brains probably possess equivalent circuitry, said Andrew Huberman, PhD, associate professor of neurobiology and of ophthalmology. So, finding ways to noninvasively shift the balance between the signaling strengths of the two nuclei in advance of, or in the midst of, situations that people perceive as threatening may help people with excessive anxiety, phobias or post-traumatic stress disorder lead more normal lives.

“This opens the door to future work on how to shift us from paralysis and fear to being able to confront challenges in ways that make our lives better,” said Huberman, the senior author of a paper describing the experimental results. It was published online May 2 in Nature. Graduate student Lindsey Salay is the lead author.

Perilous life of a mouse
There are plenty of real threats in a mouse’s world, and the rodents have evolved to deal with those threats as best they can. For example, they’re innately afraid of aerial predators, such as a hawk or owl swooping down on them. When a mouse in an open field perceives a raptor overhead, it must make a split-second decision to either freeze, making it harder for the predator to detect; duck into a shelter, if one is available; or to run for its life.

To learn how brain activity changes in the face of such a visual threat, Salay simulated a looming predator’s approach using a scenario devised some years ago by neurobiologist Melis Yilmaz Balban, PhD, now a postdoctoral scholar in Huberman’s lab. It involves a chamber about the size of a 20-gallon fish tank, with a video screen covering most of its ceiling. This overhead screen can display an expanding black disc simulating a bird-of-prey’s aerial approach.

Looking for brain regions that were more active in mice exposed to this “looming predator” than in unexposed mice, Salay pinpointed a structure called the ventral midline thalamus, or vMT.

Salay mapped the inputs and outputs of the vMT and found that it receives sensory signals and inputs from regions of the brain that register internal brain states, such as arousal levels. But in contrast to the broad inputs the vMT receives, its output destination points were remarkably selective. The scientists traced these outputs to two main destinations: the basolateral amygdala and the medial prefrontal cortex. Previous work has tied the amygdala to the processing of threat detection and fear, and the medial prefrontal cortex is associated with high-level executive functions and anxiety.

Further inquiry revealed that the nerve tract leading to the basolateral amygdala emanates from a nerve-cell cluster in the vMT called the xiphoid nucleus. The tract that leads to the medial prefrontal cortex, the investigators learned, comes from a cluster called the nucleus reuniens, which snugly envelopes the xiphoid nucleus.

Next, the investigators selectively modified specific sets of nerve cells in mice’s brains so they could stimulate or inhibit signaling in these two nerve tracts. Exclusively stimulating xiphoid activity markedly increased mice’s propensity to freeze in place in the presence of a perceived aerial predator. Exclusively boosting activity in the tract running from the nucleus reuniens to the medial prefrontal cortex in mice exposed to the looming-predator stimulus radically increased a response seldom seen under similar conditions in the wild or in previous open-field experiments: The mice stood their ground, right out in the open, and rattled their tails, an action ordinarily associated with aggression in the species.

Thumping tails

This “courageous” behavior was unmistakable, and loud, Huberman said. “You could hear their tails thumping against the side of the chamber. It’s the mouse equivalent of slapping and beating your chest and saying, ‘OK, let’s fight!’” The mice in which the nucleus reuniens was stimulated also ran around more in the chamber’s open area, as opposed to simply running toward hiding places. But it wasn’t because nucleus reuniens stimulation put ants in their pants; in the absence of a simulated looming predator, the same mice just chilled out.

In another experiment, the researchers showed that stimulating mice’s nucleus reuniens for 30 seconds before displaying the “looming predator” induced the same increase in tail rattling and running around in the unprotected part of the chamber as did vMT stimulation executed concurrently with the display. This suggests, Huberman said, that stimulating nerve cells leading from the nucleus reunions to the prefrontal cortex induces a shift in the brain’s internal state, predisposing mice to act more boldly.

Another experiment pinpointed the likely nature of that internal-state shift: arousal of the autonomic nervous system, which kick-starts the fight, flight or freeze response. Stimulating either the vMT as a whole or just the nucleus reuniens increased the mice’s pupil diameter — a good proxy of autonomic arousal.

On repeated exposures to the looming-predator mockup, the mice became habituated. Their spontaneous vMT firing diminished, as did their behavioral responses. This correlates with lowered autonomic arousal levels.

Human brains harbor a structure equivalent to the vMT, Huberman said. He speculated that in people with phobias, constant anxiety or PTSD, malfunctioning circuitry or traumatic episodes may prevent vMT signaling from dropping off with repeated exposure to a stress-inducing situation. In other experiments, his group is now exploring the efficacy of techniques, such as deep breathing and relaxation of visual fixation, in adjusting the arousal states of people suffering from these problems. The thinking is that reducing vMT signaling in such individuals, or altering the balance of signaling strength from their human equivalents of the xiphoid nucleus and nucleus reuniens may increase their flexibility in coping with stress.

Reference:
Salay, L. D., Ishiko, N., & Huberman, A. D. (2018). A midline thalamic circuit determines reactions to visual threat. Nature. doi:10.1038/s41586-018-0078-2

http://med.stanford.edu/news/all-news/2018/05/scientists-find-fear-courage-switches-in-brain.html

Ever get chills listening to a particularly moving piece of music? You can thank the salience network of the brain for that emotional joint. Surprisingly, this region also remains an island of remembrance that is spared from the ravages of Alzheimer’s disease. Researchers at the University of Utah Health are looking to this region of the brain to develop music-based treatments to help alleviate anxiety in patients with dementia. Their research will appear in the April online issue of The Journal of Prevention of Alzheimer’s Disease.

“People with dementia are confronted by a world that is unfamiliar to them, which causes disorientation and anxiety” said Jeff Anderson, M.D., Ph.D., associate professor in Radiology at U of U Health and contributing author on the study.“We believe music will tap into the salience network of the brain that is still relatively functioning.”

Previous work demonstrated the effect of a personalized music program on mood for dementia patients. This study set out to examine a mechanism that activates the attentional network in the salience region of the brain. The results offer a new way to approach anxiety, depression and agitation in patients with dementia. Activation of neighboring regions of the brain may also offer opportunities to delay the continued decline caused by the disease.

For three weeks, the researchers helped participants select meaningful songs and trained the patient and caregiver on how to use a portable media player loaded with the self-selected collection of music.

“When you put headphones on dementia patients and play familiar music, they come alive,” said Jace King, a graduate student in the Brain Network Lab and first author on the paper. “Music is like an anchor, grounding the patient back in reality.”

Using a functional MRI, the researchers scanned the patients to image the regions of the brain that lit up when they listened to 20-second clips of music versus silence. The researchers played eight clips of music from the patient’s music collection, eight clips of the same music played in reverse and eight blocks of silence. The researchers compared the images from each scan.

The researchers found that music activates the brain, causing whole regions to communicate. By listening to the personal soundtrack, the visual network, the salience network, the executive network and the cerebellar and corticocerebellar network pairs all showed significantly higher functional connectivity.

“This is objective evidence from brain imaging that shows personally meaningful music is an alternative route for communicating with patients who have Alzheimer’s disease,” said Norman Foster, M.D., Director of the Center for Alzheimer’s Care at U of U Health and senior author on the paper.“Language and visual memory pathways are damaged early as the disease progresses, but personalized music programs can activate the brain, especially for patients who are losing contact with their environment.”

However, these results are by no means conclusive. The researchers note the small sample size (17 participants) for this study. In addition, the study only included a single imaging session for each patient. It is remains unclear whether the effects identified in this study persist beyond a brief period of stimulation or whether other areas of memory or mood are enhanced by changes in neural activation and connectivity for the long term.

“In our society, the diagnoses of dementia are snowballing and are taxing resources to the max,” Anderson said. “No one says playing music will be a cure for Alzheimer’s disease, but it might make the symptoms more manageable, decrease the cost of care and improve a patient’s quality of life.”

https://www.technologynetworks.com/neuroscience/news/music-activation-of-salience-network-could-alleviate-anxiety-in-alzheimers-disease-300268?utm_campaign=Newsletter_TN_BreakingScienceNews&utm_source=hs_email&utm_medium=email&utm_content=62522460&_hsenc=p2ANqtz-9ihWyFIxhX4_ZqRqTTeOrNwa0ZHtTKERWsL_8k0sb5boN7jUkYGkdh9HwUwTgNxQfBVCpLL2CkwNk4uJpbMDlvKJPNJw&_hsmi=62522460