A network that spreads light and the role of thalamus in our brain

September 22, 2023

Science Daily/University of Liège

New research conducted at the University of Liège, using ultra-high field 7 Tesla MRI, provides a better understanding of how light stimulates our brain and could provide new insights into how it works.

A research team at the ULiège GIGA Institute tried to understand better how light stimulates our cognition. Light acts like a cup of coffee and helps keep us awake. That's why we recommend not using too much light on our smartphones and tablets in the evening. This can disrupt our sleep. On the other hand, the same light can help us during the day. Many studies have shown that good lighting can help students in schools, hospital staff and patients, and company employees. It's the blue part of the light that's most effective for this, as we have blue light detectors in our eyes that tell our brains about the quality and quantity of light around us.

Once again, the brain regions responsible for this stimulating impact of light (also known as the 'non-visual' impact of light) are not well understood. "They are small and located in the subcortical part of the brain," explains Ilenia Paparella, doctoral student in the GIGA CRC IVI laboratory and first author of the article published in Communications Biology. The team of researchers from the GIGA-CRC-IVI was once again able to take advantage of the higher resolution of 7 Tesla MRI to show that the thalamus, a subcortical region located just below the corpus callosum (that connects our two hemispheres), plays a role in relaying non-visual light information to the parietal cortex in an area known to control attention levels. "We knew of its important role in vision, but its role in non-visual aspects was not yet certain. With this study, we have demonstrated that the thalamus stimulates the parietal regions and not the other way around, as we might have thought."

These new advances in our knowledge of the role of the thalamus will ultimately enable us to propose lighting solutions that will help cognition when we need to be fully awake and focused, or that will contribute to better sleep through relaxing light.

https://www.sciencedaily.com/releases/2023/09/230922110728.htm

Suppressing negative thoughts may be good for mental health after all

September 20, 2023

Science Daily/University of Cambridge

The commonly-held belief that attempting to suppress negative thoughts is bad for our mental health could be wrong, a new study from scientists at the University of Cambridge suggests.

Researchers at the Medical Research Council (MRC) Cognition and Brain Sciences Unit trained 120 volunteers worldwide to suppress thoughts about negative events that worried them, and found that not only did these become less vivid, but that the participants' mental health also improved.

"We're all familiar with the Freudian idea that if we suppress our feelings or thoughts, then these thoughts remain in our unconscious, influencing our behaviour and wellbeing perniciously," said Professor Michael Anderson.

"The whole point of psychotherapy is to dredge up these thoughts so one can deal with them and rob them of their power. In more recent years, we've been told that suppressing thoughts is intrinsically ineffective and that it actually causes people to think the thought more -- it's the classic idea of 'Don't think about a pink elephant'.

These ideas have become dogma in the clinical treatment realm, said Anderson, with national guidelines talking about thought avoidance as a major maladaptive coping behaviour to be eliminated and overcome in depression, anxiety, PTSD, for example.

When COVID-19 appeared in 2020, like many researchers, Professor Anderson wanted to see how his own research could be used to help people through the pandemic. His interest lay in a brain mechanism known as inhibitory control -- the ability to override our reflexive responses -- and how it might be applied to memory retrieval, and in particular to stopping the retrieval of negative thoughts when confronted with potent reminders to them.

Dr Zulkayda Mamat -- at the time a PhD student in Professor Anderson's lab and at Trinity College, Cambridge -- believed that inhibitory control was critical in overcoming trauma in experiences occurring to herself and many others she has encountered in life. She had wanted to investigate whether this was an innate ability or something that was learnt -- and hence could be taught.

Dr Mamat said: "Because of the pandemic, we were seeing a need in the community to help people cope with surging anxiety. There was already a mental health crisis, a hidden epidemic of mental health problems, and this was getting worse. So with that backdrop, we decided to see if we could help people cope better."

Professor Anderson and Dr Mamat recruited 120 people across 16 countries to test whether it might in fact be possible -- and beneficial -- for people to practice suppressing their fearful thoughts. Their findings are published today in Science Advances.

In the study, each participant was asked to think of a number of scenarios that might plausibly occur in their lives over the next two years -- 20 negative 'fears and worries' that they were afraid might happen, 20 positive 'hopes and dreams', and 36 routine and mundane neutral events. The fears had to be worries of current concern to them, that have repeatedly intruded in their thoughts.

Each event had to be specific to them and something they had vividly imagined occurring. For each scenario, they were to provide a cue word (an obvious reminder that could be used to evoke the event during training) and a key detail (a single word expressing a central event detail). For example:

• Negative -- visiting one's parents at the hospital as a result of COVID-19, with the cue 'Hospital' and the detail 'Breathing'.

• Neutral -- a visit to the opticians, with the cue 'Optician' and the detail 'Cambridge'.

• Positive -- seeing one's sister get married, with the cue 'Wedding' and the detail 'Dress'.

Participants were asked to rate each event on a number of points: vividness, likelihood of occurrence, distance in the future, level of anxiety about the event (or level of joy for positive events), frequency of thought, degree of current concern, long-term impact, and emotional intensity.

Participants also completed questionnaires to assess their mental health, though no one was excluded, allowing the researchers to look at a broad range of participants, including many with serious depression, anxiety, and pandemic-related post-traumatic stress.

Then, over Zoom, Dr Mamat took each participant through the 20-minute training, which involved 12 'No-imagine' and 12 'Imagine' repetitions for events, each day for three days.

For No-imagine trials, participants were given one of their cue words, asked to first acknowledge the event in their mind. Then, while continuing to stare directly at the reminder cue, they were asked to stop thinking about the event -- they should not try to imagine the event itself or use diversionary thoughts to distract themselves, but rather should try to block any images or thoughts that the reminder might evoke. For this part of the trial, one group of participants was given their negative events to suppress and the other given their neutral ones.

For Imagine trials, participants were given a cue word and asked to imagine the event as vividly as possible, thinking what it would be like and imagining how they would feel at the event. For ethical reasons, no participant was given a negative event to imagine, but only positive or neutral ones.

At the end of the third day and again three months later, participants were once again asked to rate each event on vividness, level of anxiety, emotional intensity, etc., and completed questionnaires to assess changes in depression, anxiety, worry, affect, and wellbeing, key facets of mental health.

Dr Mamat said: "It was very clear that those events that participants practiced suppressing were less vivid, less emotionally anxiety-inducing, than the other events and that overall, participants improved in terms of their mental health. But we saw the biggest effect among those participants who were given practice at suppressing fearful, rather than neutral, thoughts."

Following training -- both immediately and after three months -- participants reported that suppressed events were less vivid and less fearful. They also found themselves thinking about these events less.

Suppressing thoughts even improved mental health amongst participants with likely post-traumatic stress disorder. Among participants with post-traumatic stress who suppressed negative thoughts, their negative mental health indices scores fell on average by 16% (compared to a 5% fall for similar participants suppressing neutral events), whereas positive mental health indices scores increased by almost 10% (compared to a 1% fall in the second group).

In general, people with worse mental health symptoms at the outset of the study improved more after suppression training, but only if they suppressed their fears. This finding directly contradicts the notion that suppression is a maladaptive coping process.

Suppressing negative thoughts did not lead to a 'rebound', where a participant recalled these events more vividly. Only one person out of 120 showed higher detail recall for suppressed items post-training, and just six of the 61 participants that suppressed fears reported increased vividness for No-Imagine items post-training, but this was in line with the baseline rate of vividness increases that occurred for events that were not suppressed at all.

"What we found runs counter to the accepted narrative," said Professor Anderson. "Although more work will be needed to confirm the findings, it seems like it is possible and could even be potentially beneficial to actively suppress our fearful thoughts."

Although participants were not asked to continue practising the technique, many of them chose to do so spontaneously. When Dr Mamat contacted the participants after three months, she found that the benefits in terms of reduced levels of depression and negative emotions, continued for all participants, but were most pronounced among those participants who continued to use the technique in their daily lives.

"The follow up was my favourite time of my entire PhD, because every day was just joyful," she said. "I didn't have a single participant who told me 'Oh, I feel bad' or 'This was useless'. I didn't prompt them or ask 'Did you find this helpful?' They were just automatically telling me how helpful they found it."

One participant was so impressed by the technique that she taught her daughter and her own mother how to do it. Another reported how she had moved home just prior to COVID-19 and so felt very isolated during the pandemic.

"She said this study had come exactly at the time she needed it because she was having all these negative thoughts, all these worries and anxiety about the future, and this really, really helped her," said Dr Mamat. "My heart literally just melted, I could feel goosebumps all over me. I said to her 'If everyone else hated this experiment, I would not care because of how much this benefited you!'."

https://www.sciencedaily.com/releases/2023/09/230920152308.htm

At which age we are at our happiest?

September 19, 2023

Science Daily/Ruhr-University Bochum

At what age are people at their happiest? This seemingly simple question has been studied extensively over the past decades, but a definitive answer has long been elusive. A research team has now shed light on the question in a comprehensive meta-analytic review. The findings show that the respondents' life satisfaction decreased between the ages of 9 and 16, then increased slightly until the age of 70, and then decreased once again until the age of 96.

An evaluation of over 400 samples shows how subjective well-being develops over the course of a lifespan.

More than 460,000 participants

In their study, the researchers examined trends in subjective well-being over the lifespan based on 443 samples from longitudinal studies with a total of 460,902 participants. "We focused on changes in three central components of subjective well-being," explains Professor Susanne Bücker, who initially worked on the study in Bochum and has since moved to Cologne: "Life satisfaction, positive emotional states and negative emotional states."

The findings show that the life satisfaction decreased between the ages of 9 and 16, then increased slightly until the age of 70, and then decreased once again until the age of 96. Positive emotional states showed a general decline from age 9 to age 94, while negative emotional states fluctuated slightly between ages 9 and 22, then declined until age 60 and then increased once again. The authors identified greater median changes in positive and negative emotional states than in life satisfaction.

Positive trend over a wide period of life

"Overall, the study indicated a positive trend over a wide period of life, if we look at life satisfaction and negative emotional states," as Susanne Bücker sums up the results. The researchers attribute the slight decline in life satisfaction between the ages of 9 and 16 to, for example, changes to the body and to the social life that take place during puberty. Satisfaction rises again from young adulthood onwards. Positive feelings tend to decrease from childhood to late adulthood. In very late adulthood, all components of subjective well-being tended to worsen rather than improve. "This could be related to the fact that in very old people, physical performance decreases, health often deteriorates, and social contacts diminish; not least because their peers pass away," speculates the researcher.

The study highlights the need to consider and promote subjective well-being with its various components across the lifespan, as the authors of the study conclude. Their findings could provide significant guidance for the development of intervention programmes, especially those aimed at maintaining or improving subjective well-being late in life.

https://www.sciencedaily.com/releases/2023/09/230919155016.htm

Job strain combined with high efforts and low reward doubled men's heart disease risk

These psychosocial stressors are each associated with heart disease risk and the combination was especially dangerous to men, finds study in Circulation: Cardiovascular Quality and Outcomes journal

September 19, 2023

Science Daily/American Heart Association

Men who say they have stressful jobs and also feel they exert high efforts for low reward had double the risk of heart disease compared to men free of those stressors, according to new research published today in Circulation: Cardiovascular Quality and Outcomes, a peer-reviewed American Heart Association journal.

"Considering the significant amount of time people spend at work, understanding the relationship between work stressors and cardiovascular health is crucial for public health and workforce well-being," said lead study author Mathilde Lavigne-Robichaud, R.D., M.S., doctoral candidate, Population Health and Optimal Health Practices Research Unit, CHU de Quebec-University Laval Research Center in Quebec, Canada. "Our study highlights the pressing need to proactively address stressful working conditions, to create healthier work environments that benefit employees and employers."

Heart disease is the No. 1 cause of death in the U.S. according to American Heart Association statistics. In 2020, nearly 383,000 Americans died of heart disease.

Research has shown that two psychosocial stressors -- job strain and effort-reward imbalance at work -- may increase heart disease risk. However, few studies have examined the combined effect.

"Job strain refers to work environments where employees face a combination of high job demands and low control over their work. High demands can include a heavy workload, tight deadlines and numerous responsibilities, while low control means the employee has little say in decision-making and how they perform their tasks," Lavigne-Robichaud explained.

"Effort-reward imbalance occurs when employees invest high effort into their work, but they perceive the rewards they receive in return -- such as salary, recognition or job security -- as insufficient or unequal to the effort. For instance, if you're always going above and beyond, but you feel like you're not getting the credit or rewards you deserve, that's called effort-reward imbalance."

The study found:

• Men who said they experienced either job strain or effort-reward imbalance had a 49% increase in risk of heart disease compared to men who didn't report those stressors.

• Men reporting both job strain and effort-reward imbalance were at twice the risk of heart disease compared with men who did not say they were experiencing the combined stressors.

• The impact of psychosocial stress at work on women's heart health was inconclusive.

• In men, the impact of job strain and effort-reward imbalance combined was similar to the magnitude of the impact of obesity on the risk of coronary heart disease.

"Our results suggest that interventions aimed at reducing stressors from the work environment could be particularly effective for men and could also have positive implications for women, as these stress factors are associated with other prevalent health issues such as depression," Lavigne-Robichaud said. "The study's inability to establish a direct link between psychosocial job stressors and coronary heart disease in women signals the need for further investigation into the complex interplay of various stressors and women's heart health."

Interventions might include different approaches, such as providing support resources, promoting work-life balance, enhancing communication and empowering employees to have more control over their work, she said.

"The U.S. workforce is among the most stressed in the world, and these workplace stressors can be as harmful to health as obesity and secondhand smoke," Eduardo J. Sanchez, M.D., M.P.H., FAHA, FAAFP, chief medical officer for prevention at the American Heart Association. "This study adds to the growing body of evidence that the workplace should be prioritized as a vehicle for advancing cardiovascular health for all. The American Heart Association remains committed to and engaged in providing employers with the resources and information they need to actively support the health of their employees and communities through science-backed changes to policy and culture."

Study background and details:

• Researchers studied nearly 6,500 white-collar workers, average age about 45 years old, without heart disease, and followed them for 18 years, from 2000 to 2018.

• They studied health and workplace survey information for 3,118 men and 3,347 women in a wide range of jobs in Quebec. The surveys included employees working in senior management, professional, technical and office workers roles. Education levels ranged from no high school diploma to university degree.

• Researchers measured job strain and effort-reward imbalance with results from proven questionnaires and retrieved heart disease information using established health databases.

One study limitation is that the researchers studied men and women in white-collar jobs primarily in Quebec, Canada, and the results might not fully represent the diversity of the American working population. However, the study findings may be relevant to white-collar workers in the United States and other high-income countries with similar job structures, according to Lavigne-Robichaud.

https://www.sciencedaily.com/releases/2023/09/230919155014.htm

New evidence indicates patients recall death experiences after cardiac arrest

September 14, 2023

Science Daily/Elsevier

Up to an hour after their hearts had stopped, some patients revived by cardiopulmonary resuscitation (CPR) had clear memories afterward of experiencing death and had brain patterns while unconscious linked to thought and memory, report investigators in the journal Resuscitation, published by Elsevier.

In a study led by researchers at NYU Grossman School of Medicine, in cooperation with 25 mostly US and British hospitals, some survivors of cardiac arrest described lucid death experiences that occurred while they were seemingly unconscious. Despite immediate treatment, fewer than 10% of the 567 patients studied, who received CPR in the hospital, recovered sufficiently to be discharged. Four in 10 of patients who survived, however, recalled some degree of consciousness during CPR not captured by standard measures.

The study also found that in a subset of these patients, who received brain monitoring, nearly 40% had brain activity that returned to normal, or nearly normal, from a "flatline" state, at points even an hour into CPR. As captured by EEG, a technology that records brain activity with electrodes, the patients saw spikes in the gamma, delta, theta, alpha, and beta waves associated with higher mental function.

Survivors have long reported having heightened awareness and powerful, lucid experiences, say the study authors. These have included a perception of separation from the body, observing events without pain or distress, and a meaningful evaluation of their actions and relationships. This new work found these experiences of death to be different from hallucinations, delusions, illusions, dreams, or CPR-induced consciousness.

The study authors hypothesize that the "flatlined," dying brain removes natural inhibitory (braking) systems. These processes, known collectively as disinhibition, may open access to "new dimensions of reality," they say, including lucid recall of all stored memories from early childhood to death, evaluated from the perspective of morality. While no one knows the evolutionary purpose of this phenomenon, it "opens the door to a systematic exploration of what happens when a person dies."

Senior study author Sam Parnia, MD, PhD, associate professor in the Department of Medicine at NYU Langone Health and director of critical care and resuscitation research at NYU Langone, says, "Although doctors have long thought that the brain suffers permanent damage about 10 minutes after the heart stops supplying it with oxygen, our work found that the brain can show signs of electrical recovery long into ongoing CPR. This is the first large study to show that these recollections and brain wave changes may be signs of universal, shared elements of so-called near-death experiences."

Dr. Parnia adds, "These experiences provide a glimpse into a real, yet little understood dimension of human consciousness that becomes uncovered with death. The findings may also guide the design of new ways to restart the heart or prevent brain injuries and hold implications for transplantation."

Called the AWAreness during REsuscitation (AWARE)-II study -- it followed 567 men and women who suffered cardiac arrest during hospital stays between May 2017 and March 2020 in the United States and United Kingdom. Only hospitalized patients were enrolled to standardize the CPR and resuscitation methods used, as well as recording methods for brain activity. A subset of 85 patients received brain monitoring during CPR. Additional testimony from 126 community survivors of cardiac arrest with self-reported memories was also examined to provide greater understanding of the themes related to the recalled experience of death.

The study authors conclude that research to date has neither proved nor disproved the reality or meaning of patients' experiences and claims of awareness in relation to death. They say the recalled experience surrounding death merits further empirical investigation and plan to conduct studies that more precisely define biomarkers of clinical consciousness and that monitor the long-term psychological effects of resuscitation after cardiac arrest.

https://www.sciencedaily.com/releases/2023/09/230914175140.htm

A quarter of people are undoing the benefits of healthy meals by unhealthy snacking

September 14, 2023

Science Daily/King's College London

A quarter of people are undoing the benefits of healthy meals with unhealthy snacks, which increases the risk of strokes and cardiovascular disease.

The findings, published today in the European Journal of Nutrition by researchers from the School of Life Course & Population Sciences and ZOE, details the snacking habits of 854 people from the ZOE PREDICT study.

Researchers found that half of the participants do not match the healthiness of their meals to their snacks and vice versa. This difference has a negative effect on health measures, such as blood sugar and fat levels, and addressing this could be a simple diet strategy to improve health.

Dr Sarah Berry from King's College London and chief scientist at ZOE said: "Considering 95% of us snack, and that nearly a quarter of our calories come from snacks, swapping unhealthy snacks such as cookies, crisps and cakes to healthy snacks like fruit and nuts is a really simple way to improve your health."

The analysis showed that the UK is a nation of snackers, with 24% of our daily energy intake from snacks such as cereal bars, pastries and fruit. The average daily snack intake in people who snack -- 95% of the cohort -- was 2.28 snacks a day, with 47% of people eating two snacks a day and 29% of people eating more than two.

Contrary to popular belief, the analysis showed that snacking is not unhealthy -- as long as the snacks were healthy. People who ate high-quality snacks like nuts and fresh fruits frequently were more likely to have a healthy weight compared to those who don't snack at all or those who snack on unhealthy foods. Analysis also showed good quality snacks can also result in better metabolic health and decreased hunger.

However, a quarter (26%) of the participants reported eating healthy main meals and poor-quality snacks. Poor-quality snacks, such as highly processed food and sugary treats, were associated with poorer health markers and left people feeling hungry. Unhealthy snacks were linked with higher BMI, higher visceral fat mass and higher postprandial -- the period after eating a meal -- triglycerides concentrations, all of which are associated with metabolic disease such as stroke, cardiovascular disease and obesity.

The most popular snacks consumed were cookies, fruit, nuts and seeds, cheese and butter, cakes and pies and granola or cereal bars. The greatest contribution to calorie intake were cakes and pies (14%), breakfast cereals (13%), ice cream and frozen dairy desserts (12%), donuts and pastries (12%), candy (11%), cookies and brownies (11%), nuts and seeds (11%).

The timing of the snacking can also be crucial to your health, as analysis showed snacking after 9pm was associated with poorer blood markers compared to all other snacking times. Snackers at this time tended to eat energy-dense foods which were high in fat and sugar.

Dr Kate Bermingham from King's College London and senior scientist at ZOE said: "This study contributes to the existing literature that food quality is the driving factor in positive health outcomes from food. Making sure we eat a balanced diet of fruit, vegetables, protein and legumes is the best way to improve your health."

https://www.sciencedaily.com/releases/2023/09/230914224038.htm

All work and no play will really make a dull life

September 14, 2023

Science Daily/University of Essex

Prioritizing career goals over fun and freedom doesn't make your life better, researchers have found. The study across three countries discovered people who prioritized achievement over enjoyment were less happy on the next day.

The study across three countries led by the Department of Psychology's Dr Paul Hanel discovered people who prioritised achievement over enjoyment were less happy on the next day.

Whereas those who aimed for freedom said they had a 13% increase in well-being, recording better sleep quality and life satisfaction.

And participants who tried to relax and follow their hobbies recorded an average well-being boost of 8% and a 10% drop in stress and anxiety.

Dr Hanel worked with colleagues at the University of Bath on the Journal of Personality-published study.

For the first time, it explored how following various values impacts our happiness.

Dr Hanel said: "We all know the old saying 'All work and no play makes Jack a dull boy' and this study shows it might actually be true.

"There is no benefit to well-being in prioritising achievement over fun and autonomy.

"This research shows that there are real benefits to having a balanced life and taking time to focus on enjoying ourselves and following individual goals.

"Ironically by doing this, people could in fact be more successful as they will be more relaxed, happier and satisfied."

The study -Value Fulfilment and Well-being: Clarifying Directions Over Time -- examined more than 180 people in India, Turkey and the UK.

They filled in a diary across nine days and recorded how following different values affected them.

Interestingly all nationalities reported the same results with the following of 'hedonism' and 'self-direction' values leading to increased happiness.

'Achievement' and 'conformity' values had no impact on happiness whatsoever.

However, the researchers believe achievement could impact on happiness when linked to job satisfaction or the amount of days worked.

Professor Greg Maio, University of Bath, said: "This multination project was an exciting foray into questions about how values affect well-being in day-to-day life.

"People often spend most of their days working hard for their daily income, studies, and careers.

"Against this backdrop, where achievement-oriented values have ring-fenced a great portion of our time, we found that it helps to value freedom and other values just enough to bring in balance and recovery.

"In the future, it will be interesting to consider how this pattern interacts with relevant traits, such as conscientiousness, and situational contexts, such as type of employment."

It is hoped the research will now influence mental health provision and influence therapeutic give to clients.

Dr Hanel added: "Our research further shows that it might be more important to focus on increasing happiness rather than reducing anxiety and stress, which is of course also important, just not as much."

https://www.sciencedaily.com/releases/2023/09/230914103346.htm

Your body's own cannabinoid molecules calm you during stress

Scientists discover how stress activates the same receptors as THC

September 12, 2023

Science Daily/Northwestern University

When you are under stress, your brain may release its own cannabinoid molecules to calm you down, activating the same brain receptors as THC derived from cannabis plants.

But the brain activity patterns and neural circuits that are regulated by these brain-derived cannabinoid molecules were not well known.

A new Northwestern Medicine study in mice has discovered that a key emotional brain center, the amygdala, releases endogenous (the body's own) cannabinoid molecules under stress, and these molecules dampen the incoming stress alarm from the hippocampus, a memory and emotion center in the brain. These results provide more support for the hypothesis that these endogenous cannabinoid molecules are a body's natural coping response to stress.

Stress exposure heightens risk for the development or worsening of psychiatric disorders from generalized anxiety and major depression to post-traumatic stress disorder (PTSD).

"Understanding how the brain adapts to stress at the molecular, cellular and circuit level could provide critical insight into how stress is translated into mood disorders and may reveal novel therapeutic targets for the treatment of stress-related disorders," said corresponding study author Dr. Sachi Patel, chair of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine and a Northwestern Medicine psychiatrist.

The study could indicate that impairments in this endogenous cannabinoid signaling system in the brain could lead to a greater susceptibility to developing stress-related psychiatric disorders including depression and PTSD, although this remains to be determined in humans, Patel said.

The study will be published Sept. 12 in Cell Reports.

For the study, Northwestern scientists used a new protein sensor that can detect the presence of these cannabinoid molecules at specific brain synapses in real time to show that specific high-frequency patterns of amygdala activity can generate these molecules. The sensor also showed that these molecules were released as a result of several different types of stress in mice.

When scientists removed the target of these cannabinoids, the cannabinoid receptor type 1, it resulted in poorer ability to cope with stress and motivational deficits in the mice. Specifically, when the receptor target of these endogenous cannabinoids was removed at hippocampal-amygdala synapses, mice adopted more passive and immobile responses to stress and had a lower preference to drink a sweetened sucrose water after stress exposure. The latter finding may relate to anhedonia, or the decrease in pleasure, often experienced by patients with stress-related disorders such as depression and PTSD.

One of the leading signaling systems that has been identified as a prominent drug-development candidate for stress-related psychiatric disorders is the endocannabinoid system, Patel said.

"Determining whether increasing levels of endogenous cannabinoids can be used as potential therapeutics for stress-related disorders is a next logical step from this study and our previous work," said Patel, also the Lizzie Gilman Professor of Psychiatry and Behavioral Sciences. "There are ongoing clinical trials in this area that may be able to answer this question in the near future."

Other Northwestern authors include Farhana Yasmin, Amanda Morgan and Keenan Johnson.

The title of the article is "Endocannabinoid release at ventral hippocampal-amygdala synapses regulates stress-induced behavioral adaptation."

https://www.sciencedaily.com/releases/2023/09/230912113528.htm

Healthy lifestyle can help prevent depression -- and new research may explain why

September 11, 2023

Science Daily/University of Cambridge

A healthy lifestyle that involves moderate alcohol consumption, a healthy diet, regular physical activity, healthy sleep and frequent social connection, while avoiding smoking and too much sedentary behaviour, reduces the risk of depression, new research has found.

In research published today in Nature Mental Health, an international team of researchers, including from the University of Cambridge and Fudan University, looked at a combination of factors including lifestyle factors, genetics, brain structure and our immune and metabolic systems to identify the underlying mechanisms that might explain this link.

According to the World Health Organization, around one in 20 adults experiences depression, and the condition poses a significant burden on public health worldwide. The factors that influence the onset of depression are complicated and include a mixture of biological and lifestyle factors.

To better understand the relationship between these factors and depression, the researchers turned to the UK Biobank, a biomedical database and research resource containing anonymised genetic, lifestyle and health information about its participants.

By examining data from almost 290,000 people -- of whom 13,000 had depression -- followed over a nine-year period, the team was able to identify seven healthy lifestyle factors linked with a lower risk of depression. These were:

• moderate alcohol consumption

• healthy diet

• regular physical activity

• healthy sleep

• never smoking

• low-to-moderate sedentary behaviour

• frequent social connection

Of all of these factors, having a good night's sleep -- between seven and nine hours a night -- made the biggest difference, reducing the risk of depression, including single depressive episodes and treatment-resistant depression, by 22%.

Frequent social connection, which in general reduced the risk of depression by 18%, was the most protective against recurrent depressive disorder.

Moderate alcohol consumption decreased the risk of depression by 11%, healthy diet by 6%, regular physical activity by 14%, never smoking by 20%, and low-to-moderate sedentary behaviour by 13%.

Based on the number of healthy lifestyle factors an individual adhered to, they were assigned to one of three groups: unfavourable, intermediate, and favourable lifestyle. Individuals in the intermediate group were around 41% less likely to develop depression compared to those in the unfavourable lifestyle, while those in the favourable lifestyle group were 57% less likely.

The team then examined the DNA of the participants, assigning each a genetic risk score. This score was based on the number of genetic variants an individual carried that have a known link to risk of depression. Those with the lowest genetic risk score were 25% less likely to develop depression when compared to those with the highest score -- a much smaller impact than lifestyle.

In people at high, medium, and low genetic risk for depression, the team further found that a healthy lifestyle can cut the risk of depression. This research underlines the importance of living a healthy lifestyle for preventing depression, regardless of a person's genetic risk.

Professor Barbara Sahakian, from the Department of Psychiatry at the University of Cambridge, said: "Although our DNA -- the genetic hand we've been dealt -- can increase our risk of depression, we've shown that a healthy lifestyle is potentially more important.

"Some of these lifestyle factors are things we have a degree control over, so trying to find ways to improve them -- making sure we have a good night's sleep and getting out to see friends, for example -- could make a real difference to people's lives."

To understand why a healthy lifestyle might reduce the risk of depression, the team studied a number of other factors.

First off, they examined MRI brain scans from just under 33,000 participants and found a number of regions of the brain where a larger volume -- more neurons and connections -- was linked to a healthy lifestyle. These included the pallidum, thalamus, amygdala and hippocampus.

Next, the team looked for markers in the blood that indicated problems with the immune system or metabolism (how we process food and produce energy). Among those markers found to be linked to lifestyle were the C-reactive protein, a molecule produced in the body in response to stress, and triglycerides, one of the primary forms of fat that the body uses to store energy for later.

These links are supported by a number of previous studies. For example, exposure to stress in life can affect how well we are able to regulate blood sugar, which may lead to a deterioration of immune function and accelerate age-related damage to cells and molecules in the body. Poor physical activity and lack of sleep can damage the body's ability to respond to stress. Loneliness and lack of social support have been found to increase the risk of infection and increase markers of immune deficiency.

The team found that the pathway from lifestyle to immune and metabolic functions was the most significant. In other words, a poorer lifestyle impacts on our immune system and metabolism, which in turn increases our risk of depression.

Dr Christelle Langley, also from the Department of Psychiatry at the University of Cambridge, said: "We're used to thinking of a healthy lifestyle as being important to our physical health, but it's just as important for our mental health. It's good for our brain health and cognition, but also indirectly by promoting a healthier immune system and better metabolism."

Professor Jianfeng Feng, from Fudan University and Warwick University, added: "We know that depression can start as early as in adolescence or young adulthood, so educating young people on the importance of a healthy lifestyle and its impact on mental health should begin in schools."

https://www.sciencedaily.com/releases/2023/09/230911141148.htm

'Night owls' more likely than 'early birds' to develop diabetes

September 11, 2023

Science Daily/Brigham and Women's Hospital

A new study has an important message for people who consider themselves night owls. Investigators from Brigham and Women's Hospital, a founding member of the Mass General Brigham healthcare system, found that people with later sleep and wake times had less healthy lifestyles and were at greater risk of developing diabetes than those with early-bird sleep habits.

Investigators found evening 'chronotype,' or going to bed late and waking up late, was associated with a 19 percent increased risk of diabetes after accounting for lifestyle factors

A new study has an important message for people who consider themselves night owls. Investigators from Brigham and Women's Hospital, a founding member of the Mass General Brigham healthcare system, found that people with later sleep and wake times had less healthy lifestyles and were at greater risk of developing diabetes than those with early-bird sleep habits. Their results are published in the Annals of Internal Medicine.

"Chronotype, or circadian preference, refers to a person's preferred timing of sleep and waking and is partly genetically determined so it may be difficult to change," said corresponding author Tianyi Huang, MSc, ScD, an associate epidemiologist in the Brigham's Channing Division of Network Medicine. "People who think they are 'night owls' may need to pay more attention to their lifestyle because their evening chronotype may add increased risk for type 2 diabetes."

The researchers previously found that people with more irregular sleep schedules are at higher risk of developing diabetes and cardiovascular disease and that people with evening chronotypes are more likely to have irregular sleep patterns. For this study, they wanted to understand the relationship between chronotype and diabetes risk and looked at the role of lifestyle factors as well.

The team analyzed data from 63,676 female nurses from the Nurses' Health Study II collected from 2009-2017 and included self-reported chronotype (the extent to which participants perceived themselves to be an evening person or a morning person), diet quality, weight and body mass index, sleep timing, smoking behaviors, alcohol use, physical activity, and family history of diabetes. The team determined diabetes status from the participants' self-reports and medical records.

The Nurses' Health Study II, a joint effort between the Brigham's Channing Division of Network Medicine and Harvard T.H. Chan School of Public Health, is among the largest investigations into risk factors for major chronic diseases in women. One of the study's strengths is its regular follow-up of study participants and repeated assessment of health and lifestyle factors.

Approximately 11 percent of participants reported having a 'definite evening' chronotype and about 35 percent reported having 'definite morning' chronotype. The remaining population, around half, were labeled as 'intermediate,' meaning they either identified as being neither a morning nor evening type or as being only slightly more one than the other.

The evening chronotype was associated with a 72 percent increased risk for diabetes before accounting for lifestyle factors. After accounting for lifestyle factors, evening chronotype was associated with a 19 percent increased risk of diabetes. Among those in the study with the healthiest lifestyles, only 6 percent had evening chronotypes. Among those with the unhealthiest lifestyles 25 percent were evening chronotypes.

Those with evening chronotypes were found to be more likely to drink alcohol in higher quantities, have a low-quality food diet, get less hours of sleep per night, currently smoke, and have weight, BMI, and physical activity rates in the unhealthy range.

"When we controlled for unhealthy lifestyle behaviors, the strong association between chronotype and diabetes risk was reduced but still remained, which means that lifestyle factors explain a notable proportion of this association," said first author Sina Kianersi, DVM, PhD, a postdoctoral research fellow in the Brigham's Channing Division of Network Medicine.

They also found the association between evening chronotype and diabetes risk only in those nurses who worked day shifts and not those who worked overnight shifts.

"When chronotype was not matched with work hours we saw an increase in type 2 diabetes risk," said Huang. "That was another very interesting finding suggesting that more personalized work scheduling could be beneficial."

The Nurses' Health Study is comprised mainly of white female nurses -- future investigations will be needed to determine if the patterns detected here are consistent across populations. The study's results point to associations but cannot determine causality -- it's possible that other factors may contribute to a person's chronotype, propensity for unhealthy habits and risk of diabetes.

Next, the researchers plan to investigate genetic determinants of chronotype and its association with cardiovascular disease, in addition to diabetes, in larger, more diverse populations.

"If we are able to determine a causal link between chronotype and diabetes or other diseases, physicians could better tailor prevention strategies for their patients," says Kianersi.

https://www.sciencedaily.com/releases/2023/09/230911191004.htm