New Research Suggests Why Males and Females Respond Differently to Social Stress

Emily Wright, researcher, in a UC Davis lab.
Photo Credit: Jerry Tsai

Women are nearly twice as likely as men to be diagnosed with an anxiety disorder, but among boys and girls the likelihood is the same. New University of California, Davis, research has identified changes in the brain during puberty that may account for differences in how women and men respond to stress.

A team of psychologists has found that testosterone is the key hormone that drives gender-based differences in responses to social stress. The study encompassed six separate experiments with mice to isolate what changes in the brain drive these differences between males and females. The study was published in the Proceedings of the National Academy of Sciences, or PNAS, today.

“This research shows how the body’s hormones shape the complex interplay between the brain’s circuitry and behavioral responses to stress,” said Brian Trainor, a professor of psychology in the College of Letters and Science at UC Davis and the study’s corresponding author.

The emotional function of dreams is not the same everywhere

The study by the UNIGE and the University of Toronto shows that there is a strong link between our socio-cultural life and the function of dreams.
Photo Credit: Maeghan Smulders

Why do we dream? A product of our brain’s neurophysiology, dreaming is a complex experience that can take on many emotional tones and simulate reality to varying degrees. As a result, there is still no clear answer to this question. A study led by the universities of Geneva (UNIGE) and Toronto, and the Geneva University Hospitals (HUG), compared the dreams of two forager communities, in Tanzania and the Democratic Republic of Congo, with those of individuals living in Europe and North America. It showed that the first two groups produced more threatening, but also more cathartic and socially-oriented dreams than the Western groups. These results, to be read in Scientific Reports, show how strong the links are between the socio-cultural environment and the function of dreams.

Dreaming is a hallucinatory experience common to all human beings. It occurs most often during the paradoxical phase of sleep, known as the Rapid Eye Movement (REM) phase. However, it can occur at any sleep stage. What are the physiological, emotional or cultural functions of dreams? Does it regulate our emotions? Does it prepare us to deal with a specific situation? Recent theories suggest that during a "functional" dream, the individual simulates more threatening and/or social situations, which would have an evolutionary advantage in promoting adapted behavior to real-life situations.

Cannabis intoxication triggers cognitive mechanism of addiction

Photo Credit: Matthew Brodeur

New research from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s College London and the University of Oxford has found that the main component of cannabis, delta-9-tetrahydrocannabinol (THC), leads to people’s attention being more drawn to other cannabis stimuli when using the drug, which researchers suggest could underpin the cognitive mechanisms behind cannabis use disorder (CUD).

The research, published in Addiction, also found that levels of cannabidiol (CBD) typically found in cannabis had no modulating effects on the participants, despite many users believing this to be the case.

Over the course of four sessions, researchers asked 46 infrequent cannabis users (using cannabis less than once a week) to inhale a cannabis vapour containing 10mg of THC, and either 0, 10, 20, or 30mg of CBD. They were then given a task designed to measure what they focused on more when given the choice between options of images (cannabis stimuli vs neutral and food stimuli vs neutral).

Researchers found that the acute inhalation of THC resulted in people being more drawn to cannabis-related cues without explicitly liking it more.

Cellular Atlas of Amygdala Reveals New Treatment Target for Cocaine Addiction

The study was led by co-senior authors Francesca Telese, PhD (left) and Graham McVicker, PhD (right).
Photo credit: UC San Diego Health Sciences

Researchers at University of California San Diego School of Medicine and the Salk Institute for Biological Studies have created a unique, cell-by-cell atlas of the amygdala, a small structure deep within the brain that plays a crucial role in controlling emotional responses to drugs. The findings, published October 5, 2023 in Nature Neuroscience, helped the researchers identify a potential new treatment for cocaine addiction, a disease that is poorly understood at the molecular level and has virtually no approved pharmacological treatments.

“There are some drugs that can help treat other addictions, such as those to opioids or nicotine, but there are currently no safe and effective drugs approved for cocaine addictions,” said co-senior author Francesca Telese, PhD, an associate professor in the Department of Psychiatry at UC San Diego School of Medicine. “These findings help address that problem and could also point to universal molecular mechanisms of addiction that we haven’t understood until now.”

Cocaine is a widely used illicit drug and addiction to cocaine is a major public health concern, associated with a rising number of overdose deaths and a high rate of relapse. Despite the threat cocaine addiction poses, not every person who uses cocaine develops an addiction. According to the National Institute on Drug Abuse, an estimated 4.8 million people used cocaine in 2021, while only 1.4 million people had a cocaine use disorder.

Psychedelics improve mental health, cognition in special ops veterans

The Colorado River toad (Incilius alvarius), also known as the Sonoran Desert toad, is a toad species found in northwestern Mexico and the southwestern United States. It is well known for its ability to exude toxins from glands within its skin that have psychoactive properties.
Photo Credit: Alan Schmierer
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One treatment each of two psychedelic drugs lowered depression and anxiety and improved cognitive functioning in a sample of U.S. special operations forces veterans who sought care at a clinic in Mexico, according to a new analysis of the participants’ charts. 

The treatment included a combination of ibogaine hydrochloride, derived from the West African shrub iboga, and 5-MeO-DMT, a psychedelic substance secreted by the Colorado River toad. Both are designated as Schedule I drugs under the U.S. Controlled Substances Act.

In addition to relieving symptoms of post-traumatic stress disorder (PTSD), the combined treatment also alleviated cognitive impairment linked to traumatic brain injury – which stood out to researchers from The Ohio State University who led the chart-review analysis. Many special operations forces veterans seeking treatment for complex psychiatric symptoms do not respond to more traditional therapies. 

“What sets this group apart from some other veterans and civilians is that often, they are exposed to repeated traumatic events as a routine part of their jobs. This build-up of exposure to these difficulties seems to produce a cluster of challenges that include traumatic brain injury, which we know in and of itself predisposes people to mental health problems,” said lead author Alan Davis, associate professor and director of the Center for Psychedelic Drug Research and Education (CPDRE) in Ohio State’s College of Social Work. 

“So, the fact that we saw that there were improvements in cognitive functioning linked to brain injury were probably the most striking results, because that’s something we didn’t predict and it’s very new and novel in terms of how psychedelics might help in so many different domains.” 

Small doses of mushrooms can have a beneficial effect on mental disorders

"Liberty Cap" Psilocybin mushroom
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A new research result from the University of Southern Denmark opens the door to the possibility of using psilocybin, the active compound in mushrooms with psychedelic properties, as a therapeutic tool through microdosing.

Psilocybin has long been recognized as a classic psychedelic substance and has recently been investigated for its potential to assist in the treatment of various psychiatric disorders, primarily depression and addiction, through therapy supplemented with a high dose of psilocybin.

In such therapeutic treatment, the patient takes psilocybin after thorough therapeutic preparation and undergoes a psychedelic experience in a supportive environment with a trained therapist. Subsequently, the experience is integrated over several therapy sessions.

Experiments are being conducted with patients at hospitals, including Bispebjerg Hospital and Rigshospitalet.

Discrimination alters brain-gut ‘crosstalk,’ prompting poor food choices and increased health risks

Illustration Credit: julientromeur

People frequently exposed to racial or ethnic discrimination may be more susceptible to obesity and related health risks in part because of a stress response that changes biological processes and how we process food cues. These are findings from UCLA researchers conducting what is believed to be the first study directly examining effects of discrimination on responses to different types of food as influenced by the brain-gut-microbiome (BGM) system.

The changes appear to increase activation in regions of the brain associated with reward and self-indulgence – like seeking “feel-good” sensations from “comfort foods” – while decreasing activity in areas involved in decision making and self-control.

“We examined complex relationships between self-reported discrimination exposure and poor food choices, and we can see these processes lead to increased cravings for unhealthy foods, especially sweet foods, but also manifested as alterations in the bidirectional communication between the brain and the gut microbiome,” said Arpana Gupta, PhD, a researcher and co-director of the UCLA Goodman-Luskin Microbiome Center and the UCLA G. Oppenheimer Center for Neurobiology of Stress and Resilience.

Sleep apnea link to cognitive decline

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Flinders University experts are working on better solutions for sleep apnea to ward off a range of health risks, including cognitive decline.

Improved solutions for obstructive sleep apnea (OSA), insomnia and other sleep disorders are being developed by the Flinders Sleep Health experts to reduce the associated negative health effects such as cardiovascular harm, diabetes, anxiety and depression and even long-term cognitive decline.

Heightened risk of cognitive function decline from undiagnosed OSA – particularly in middle-aged men living in the community – is the focus of one of the latest studies published in Sleep Health.

The study recorded the sleep patterns of more than 470 men aged from 41-87 years alongside their daytime cognitive function for processing speed, visual attention, episodic memory recollection and other markers.

Measuring distinct features of brain electrical activity during non-REM sleep, called ‘sleep spindles’, the study aimed to explore if these features can serve as markers of cognitive function.

“Non-REM sleep includes light stage 1 and 2 sleep, as well as deeper stage 3 sleep which is thought to play an important role in learning and memory,” says Flinders University sleep researcher Dr Jesse Parker.

New study links contraceptive pills and depression

According to the study, women who began to use contraceptive pills as teenagers had a 130 per cent higher incidence of symptoms of depression.
Photo Credit: Thought Catalog

Women who used combined contraceptive pills were at greater risk of developing depression than women who did not, according to a new study from Uppsala University. Contraceptive pills increased women’s risk by 73 per cent during the first two years of use.

In a global perspective, depression is the leading cause of ill health and disability. More than 264 million people are affected and at least 25 per cent of all women and 15 per cent of all men experience a depression that requires treatment at some point during their life.

The possibility that contraceptive pills might have negative effects on mental health and even lead to depression has long been discussed. Although many women choose to stop using contraceptive pills because of the influence on their mood, until now the picture emerging from research has not been straightforward. This study is one of the largest and widest-ranging to date, following more than a quarter of a million women from UK Biobank from birth to menopause.

Newly discovered brain mechanism linked to anxiety, OCD

Distinguished Professor Mario Capecchi, Ph.D. and Naveen Nagajaran, Ph.D.
Photo Credit: Charlie Ehlert/U of U Health

The pandemic and its aftermath have raised anxiety to new levels. But the roots of anxiety-related conditions, including obsessive-compulsive spectrum disorder (OCSD), are still unclear. In a new study, University of Utah Health scientists discovered insights into the importance of a minor cell type in the brain—microglia—in controlling anxiety-related behaviors in laboratory mice. Traditionally, neurons—the predominant brain cell type—are thought to control behavior.

The researchers showed that, like buttons on a game controller, specific microglia populations activate anxiety and OCSD behaviors while others dampen them. Further, microglia communicate with neurons to invoke the behaviors. The findings, published in Molecular Psychiatry, could eventually lead to new approaches for targeted therapies.

“A small amount of anxiety is good,” said Nobel Laureate Mario Capecchi, Ph.D., a distinguished professor of human genetics at the Spencer Fox Eccles School of Medicine at University of Utah and senior author of the study. “Anxiety motivates us, spurs us on, and gives us that extra bit of push that said, ‘I can.’ But a large dose of anxiety overwhelms us. We become mentally paralyzed, the heart beats faster, we sweat, and confusion settles in our minds.”

Clinically relevant deficiency of the “bonding hormone” oxytocin demonstrated

The hormones oxytocin and vasopressin are produced in the same area of the brain and are also very similar in structure. This is why disorders that cause vasopressin deficiency could also affect the neurons that produce oxytocin
Image Credit: Colin Behrens

The hormone oxytocin is important for social interaction and to control emotions. A deficiency of this hormone has previously been assumed, for example, in people with autism, but has never been proven. Now, for the first time, researchers from the University of Basel and the University Hospital of Basel have succeeded in demonstrating a deficiency of oxytocin in patients with a deficiency of vasopressin caused by a disease of the pituitary gland. This finding could be key to developing new therapeutic approaches.

The hormones oxytocin and vasopressin are produced in the same area of the brain and are also very similar in structure. Patients with a rare deficiency of vasopressin cannot concentrate their urine and lose liters of water as a result. In order to compensate for this loss, they are obliged to drink up to 10 liters or more per day.

With a nasal spray or a tablet containing synthetically produced vasopressin, these symptoms can usually be treated without any problems. However, even with this treatment, many patients report anxiety, have trouble with social interactions or demonstrate impaired emotional awareness.

Stress increases Alzheimer’s risk in female mice but not males

Stress causes the levels of Alzheimer's proteins to rise in females' brains but not males' brains, according to a new study in mice by researchers at Washington University School of Medicine in St. Louis. This difference may contribute to women's greater risk of developing Alzheimer's disease.
Photo Credit: Karolina Grabowska

Women are about twice as likely as men to be diagnosed with Alzheimer’s disease. Some of that is age; in the U.S., women outlive men by five to six years, and advanced age is the strongest risk factor for Alzheimer’s. But there’s more to it than that, so Alzheimer’s researchers continue to look for other reasons why women have an elevated risk of the deadly neurodegenerative disease.

Stress may be one such reason. A study by researchers at Washington University School of Medicine in St. Louis shows that the effect stress has on the brain differs by sex, at least in mice. In stressful situations, levels of the Alzheimer’s protein amyloid beta rises sharply in the brains of females but not males. In addition, the researchers identified a molecular pathway that is active in brain cells from female mice but not male mice, and showed that it accounts for the divergent responses to stress.

The findings, published May 2 in Brain, add to a growing collection of evidence that sex matters in health and disease. From cancer to heart disease to arthritis, scientists have found differences between males and females that could potentially affect how men and women respond to efforts to prevent or treat chronic diseases.

Cannabis exposures in suspected suicide attempts are on the rise

Photo Credit: Jose Luis Sanchez Pereyra

Suspected suicidal cannabis exposures have increased 17% annually, over a period of 12 years, according to a Washington State University-led analysis of U.S. poison center data.

The vast majority of the attempts, more than 92%, involved other substances in addition to cannabis, and the data cannot show a direct causal link between cannabis and suicide attempts. Still, the findings are cause for concern, the researchers said, especially since the increase was more pronounced among children and women during and after the pandemic. They reported their findings in the journal JAMA Network Open.

“This study adds to already ample evidence that cannabis use, particularly by younger people, has significant implications for mental health,” said study co-author Tracy Klein, a WSU associate professor of nursing. “We don’t have evidence that cannabis alone was the primary driver of a suicide attempt, but we do know that cannabis can worsen certain mental health conditions and increase impulsivity.”

The brain’s support cells may play a key role in OCD

An astrocye from the striatum
Image Credit: Joselyn Soto

A type of cell usually characterized as the brain’s support system appears to play an important role in obsessive-compulsive disorder-related behaviors, according to new UCLA Health research published April 12 in Nature.

The new clue about the brain mechanisms behind OCD, a disorder that is incompletely understood, came as a surprise to researchers. They originally sought to study how neurons interact with star-shaped “helper” cells known as astrocytes, which are known to provide support and protection to neurons.

However, scientists are still trying to understand the apparent role these complex cells play in psychiatric and neurodegenerative diseases.

By studying the proteins expressed by neurons and astrocytes in mice, UCLA researchers found a protein associated with OCD and repetitive behaviors in neurons was also found in astrocytes. The discovery suggests therapeutic strategies targeting astrocytes and neurons may be useful for OCD and potentially other brain disorders.

The brain’s cannabinoid system protects against addiction

Test participants’ emotional reactions are measured using electrodes that record tension in the small facial muscles. From left: Madeleine Jones and Irene Perini. 
Photo Credit: Thor Balkhed

High levels of the body’s own cannabinoid substances protect against developing addiction in individuals previously exposed to childhood maltreatment, according to a new study. Those who had not developed an addiction following childhood maltreatment seem to process emotion-related social signals better.

 Childhood maltreatment has long been suspected to increase the risk of developing a drug or alcohol addiction later in life. Researchers at Linköping University have previously shown that this risk is three times higher if you have been exposed to childhood maltreatment compared with if you have not, even when accounting for confounds from genetics and other familial factors.

“There’s been a lot of focus on addiction as a disease driven by a search for pleasure effects and euphoria, but for many it has more to do with the drugs’ ability to suppress negative feelings, stress sensitivity, anxiety and low mood. Based on this, we and other researchers have had a theory that if affected in childhood, the function of the brain’s distress systems is altered, and that this may contribute to addiction risk in adulthood,” says Markus Heilig, professor and director of the Center for Social and Affective Neuroscience, CSAN, at Linköping University and consultant at the Psychiatric Clinic of the University Hospital in Linköping.

Machine learning models rank predictive risks for Alzheimer’s disease

Xiaoyi Raymond Gao, PhD Associate Professor
Photo Credit: Courtesy of Ohio State University

Once adults reach age 65, the threshold age for the onset of Alzheimer’s disease, the extent of their genetic risk may outweigh age as a predictor of whether they will develop the fatal brain disorder, a new study suggests. 

The study, published recently in the journal Scientific Reports, is the first to construct machine learning models with genetic risk scores, non-genetic information and electronic health record data from nearly half a million individuals to rank risk factors in order of how strong their association is with eventual development of Alzheimer’s disease.

Researchers used the models to rank predictive risk factors for two populations from the UK Biobank: White individuals aged 40 and older, and a subset of those adults who were 65 or older. 

Results showed that age – which constitutes one-third of total risk by age 85, according to the Alzheimer’s Association – was the biggest risk factor for Alzheimer’s in the entire population, but for the older adults, genetic risk as determined by a polygenic risk score was more predictive. 

“We all know Alzheimer’s disease is a later-onset disease, so we know age is an important risk factor. But when we consider risk only for people age 65 or older, then genetic information captured by a polygenic risk score ranks higher than age,” said lead study author Xiaoyi Raymond Gao, associate professor of ophthalmology and visual sciences and of biomedical informatics in The Ohio State University College of Medicine. “That means it’s really important to consider genetic information when we work on Alzheimer’s disease.” 

Drug overdose fatalities among US older adults has quadrupled over 20 years

Photo Credit: Christina Victoria Craft

Overdose mortality among people age 65 and older quadrupled over 20 years, suggesting the need for greater mental health and substance use disorder policies addressed at curbing the trend, a new research paper finds.

The deaths stemmed from both suicides and accidental overdoses, with nearly three-fourths of the unintended fatalities involving illicit drugs such as synthetic opioids like fentanyl, heroin, cocaine, and methamphetamines.  Prescription opioids, antidepressants, benzodiazepines, antiepileptics and sedatives were used in 67% of intentional overdoses.

“The dramatic rise in overdose fatalities among adults over 65 years of age in the past two decades underscores how important it is for clinicians and policymakers to think of overdose as a problem across the lifespan,” said co-author Chelsea Shover, assistant professor of medicine in the division of general internal medicine and health services research at the David Geffen School of Medicine at UCLA. “Updating Medicare to cover evidence-based treatment for substance use disorders is crucial, as is providing harm reduction supplies such as naloxone to older adults.”

Use of melatonin linked to decreased self-harm in young people

There is currently a youth mental health crisis, and the risk of self-harm and suicide  is high.
Photo Credit: Vladislav Muslakov

Medical sleep treatment may reduce self-harm in young people with anxiety and depression, an observational study from Karolinska Institutet suggests. The risk of self-harm increased in the months preceding melatonin prescription and decreased thereafter, especially in girls. The study is published in The Journal of Child Psychology and Psychiatry.

Melatonin is a hormone that controls the sleep-wake cycle and is the most commonly prescribed drug for sleep disturbances in children and adolescents in Sweden. Melatonin use has dramatically increased in recent years, and it is available over the counter in Sweden since 2020.

“Given the established link between sleep problems, depression, and self-harm, we wanted to explore whether medical sleep treatment is associated with a lower rate of intentional self-harm in young people,” says Dr Sarah Bergen, docent at the Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, who led the study.

Clues to the cause of chronic gut pain

Professor Stuart Brierley
Photo Credit: Courtesy of Flinders University

New insights into chronic gut pain offer hope for improved treatments for irritable bowel syndrome and anxiety treatment.

A research team led by Flinders University Professor Stuart Brierley, based at the SA Health and Medical Research Institute, with Nobel Laureate Professor David Julius, Professor Holly Ingraham and Dr James Bayrer at the University of California San Francisco, has shown evidence of a specific pathway of cells and nerves linking the gut to the brain that may be responsible for the chronic gut pain.

Chronic gut pain is commonly experienced by 11% of the global population currently living with irritable bowel syndrome (IBS) and associated psychological conditions, including anxiety and depression.

Described in a new article in Nature, the team used genetic and pharmacologic tools in pre-clinical models to manipulate signals between gut epithelial cells and associated nerve fibers to determine how this pathway stimulates chronic gut pain and anxiety.

Epilepsy could become easier to pinpoint with blood test

Researchers from Lund University in Sweden have discovered higher levels of immune proteins in the blood before and after an epileptic seizure. The possible biomarkers can be identified using a simple blood test. Diagnosing epilepsy is currently resource intensive, and distinguishing it from other conditions can be challenging. Better diagnostic methods as soon as the patient seeks medical care after a suspected seizure is therefore an urgent necessity.

Epilepsy is the collective name for abnormal activity in the brain that causes temporary loss of control of behavior and movement. The condition can be congenital, be caused by a tumor, stroke or infection in the brain and cause very different symptoms depending on which part of the brain the episode begins in or spreads to. Inflammation processes that start as an immune response in the body can also provoke a seizure. That is why researchers started to look for possible biomarkers for epilepsy within the immune system. Previous studies exist, but the results have so far been mixed and difficult to interpret:

“In our study, we have a carefully selected group of participants and we have a lot of background information on each person. We have also taken into account a number of confounding factors that may affect the immune system such as other neurological and immunological illnesses, infections and various psychiatric conditions,” says Christine Ekdahl Clementson.