1. New risk factors for anxiety disorders

    March 20, 2017 by Ashley

    From the University of Würzburg press release:

    Mental, social and inherited factors all play a role in anxiety disorders. In the journal Molecular Psychiatry, a research team from Julius-Maximilians-Universität Würzburg (JMU) in Bavaria, Germany, describes a hitherto unknown genetic pathway for developing such diseases: They pinpointed at least four variants of the GLRB gene (glycine receptor B) as risk factors for anxiety and panic disorders. More than 5000 voluntary participants and 500 patients afflicted by panic disorder took part in the study that delivered these results.

    In Germany, around 15 percent of adults suffer from anxiety and panic disorders. Some people may have an extreme fear of spiders or other objects while others have breathing difficulties and accelerated heart beat in small rooms or large gatherings of people. With some afflicted persons, the anxiety attacks occur for no apparent cause. Many patients suffer from the detrimental impacts on their everyday lives — they often have problems at work and withdraw from social contacts.

    How are fear and anxiety triggered? How do anxiety disorders arise and evolve?

    Scientists from Münster, Hamburg and Würzburg have looked into these questions within the scope of Collaborative Research Center (CRC) TR 58 funded by Deutsche Forschungsgemeinschaft. Their goal is to develop new therapies that are better tailored to the individual patients. Anxiety disorders can be treated with drugs and behaviour therapy for instance.

    Gene triggers hyperekplexia

    The discovery that different variants of the GLRB gene are associated with anxiety disorders might also contribute to the development of improved therapies. The gene had been known to the researchers for some time, albeit only in connection with a different disease:

    “Some mutations of the gene cause a rare neurological disorder called hyperekplexia,” explains Professor Jürgen Deckert, member of the CRC and Director of the Department of Psychiatry at the JMU University Hospital. The patients are permanently hypertonic and show pronounced startle responses, which may even cause sufferers to fall involuntarily. Similar to persons suffering from anxiety disorders, these patients develop behaviour to avoid potentially frightening situations.

    The “fear network” in the brain is activated

    But the GLRB gene variants that have recently been associated with anxiety and panic disorders for the first time are different from the ones described above. They occur more frequently and presumably entail less severe consequences. But they, too, trigger overshooting startle responses, and as a result may excessively activate the brain’s “fear network.” High-resolution images of the brain activities of study participants provided the clues for the Würzburg scientists.

    “The results point to a hitherto unknown pathway of developing an anxiety disorder,” Deckert says. He believes that further investigations are now necessary to determine whether these findings can be harnessed to develop new or individual therapies. For example, it is conceivable to bring the “fear network” that is misregulated by the GLRB gene back on track by administering drugs.


  2. Anxiety is a stronger harbinger of alcohol problems than stress

    March 15, 2017 by Ashley

    From the Research Society on Alcoholism press release:

    Stress and anxiety are widely believed to contribute to drinking. Alcohol is thought to reduce tension caused by stress (the “flight or fight” response) as well as alleviate the unpleasant symptoms of anxiety (anticipation of the unpredictable, impending threats). Prior research, however, has yielded inconsistent findings as to the unique relations between stress and anxiety, on the one hand, and alcohol consumption and alcohol use disorders, on the other hand. This study was designed to examine how differences in self-reported levels of anxiety, anxiety sensitivity, and perceived stress impact the frequency and intensity of drinking, alcohol craving during early withdrawal, and alcohol craving and stress reactivity.

    Recent drinking was assessed in 87 individuals (70 men, 17 women) with alcohol use disorders (AUDs). Three distinct measures were used to evaluate anxiety, anxiety sensitivity, and perceived stress. A subset of 30 subjects was admitted to a medical center to ensure alcohol abstinence for one week: measures of alcohol craving were collected twice daily. On day 4, subjects participated in a public speaking/math challenge, before and after which measures of cortisol and alcohol craving were collected.

    In these heavy drinkers, measures of anxiety as compared with perceived stress were more strongly associated with a variety of alcohol-related measures. While alcohol studies often use the terms anxiety, anxiety sensitivity, and stress interchangeably, this study showed the importance of differentiating among the three terms given their unique relationships with drinking, craving, and stress reactivity among individuals with AUDs.


  3. Study suggests social phobia may be affected by genes

    March 14, 2017 by Ashley

    From the University of Bonn press release:

    People with social anxiety avoid situations in which they are exposed to judgment by others. Those affected also lead a withdrawn life and maintain contact above all on the Internet. Around one in ten people is affected by this anxiety disorder over the course of their life. Researchers at the University of Bonn have now found evidence for a gene that is believed to be linked to the illness. It encodes a serotonin transporter in the brain. Interestingly, this messenger suppresses feelings of anxiety and depressiveness. The scientists want to investigate this cause more precisely and are thus looking for more study participants. The results will be published in the journal Psychiatric Genetics.

    Heart palpitations, trembling and shortness of breath: those who suffer from social phobia avoid larger groups. Verbal tests or everyday arrangements are filled with fear — after all, other people could make a negative judgement. Those affected often avoid such situations for this reason. Contact is often easier over social media or anonymously over the Internet. Social phobias are among the psychiatric disorders that are triggered simultaneously by genetic and environmental factors. “There is still a great deal to be done in terms of researching the genetic causes of this illness,” says Dr. Andreas Forstner from the Institute of Human Genetics at the University of Bonn. “Until now, only a few candidate genes have been known that could be linked to this.”

    Individual base pairs can vary in the DNA

    Together with the Clinic and Policlinic for Psychosomatic Medicine and Psychotherapy at the University Hospital Bonn, Dr. Forstner is conducting a study into the genetic causes of social phobia. The research team investigated the DNA of a total of 321 patients and compared it with 804 control individuals. The focus of the scientists lay on what are known as single nucleotide polymorphisms (SNPs). “There are variable positions in the DNA that can exist to various degrees in different people,” explains Dr. Forstner.

    The cause of genetic illnesses often lies in the SNPs. It is estimated that more than thirteen million such changes exist in the human DNA. The scientists investigated a total of 24 SNPs that are suspected in the widest sense of being the cause of social phobias and other mental disorders. “This is the largest association study so far into social phobia,” says associate professor (Privatdozent) Johannes Schumacher from the Institute of Human Genetics at the University of Bonn.

    Patients provided information about their symptoms

    Over the course of the study, scientists at the Clinic and Policlinic for Psychosomatic Medicine and Psychotherapy at the University Hospital Bonn will ask the patients about their symptoms and the severity of their social phobia. Their DNA is also examined using a blood sample. Whether there is a link between the signs of the illness and the genes is being investigated by the scientists using statistical methods. The evaluation of the previously collected data indicated that an SNP in the serotonin transporter gene SLC6A4 is involved in the development of social phobia.

    This gene encodes a mechanism in the brain that is involved in transporting the important messenger serotonin. This substance suppresses, among other things, feelings of fear and depressive moods. “The result substantiates indications from previous studies that serotonin plays an important role in social phobia,” says associate professor (Privatdozent) Dr. Rupert Conrad from the Clinic and Policlinic for Psychosomatic Medicine and Psychotherapy. Medications that block serotonin reuptake and increase the concentration of the messenger in the tissue fluid in the brain have already long been used to treat anxiety disorders and depression.

    Subjects can participate in expanded study

    The scientists now want to investigate more closely what the links are between the DNA and social phobia. “In order to achieve this goal, we need many more study participants who suffer from social anxiety,” says the psychologist and study coordinator Stefanie Rambau from the Clinic and Policlinic for Psychosomatic Medicine and Psychotherapy at University Hospital Bonn. Information about the study is available at http://www.SocialPhobiaResearch.de. “Those who take part will help to research social phobia. This is the basis of better diagnosis and treatment procedures in the future,” says Stefanie Rambau.


  4. Tablet devices show promise in managing agitation among patients with dementia

    January 9, 2017 by Ashley

    From the McLean Hospital media release:

    senior researcher with tabletA new pilot study led by McLean Hospital’s Ipsit Vahia, MD, medical director of Geriatric Psychiatry Outpatient Services at McLean Hospital, suggests that the use of tablet computers is both a safe and a potentially effective approach to managing agitation among patients with dementia.

    “Tablet use as a nonpharmacologic intervention for agitation in older adults, including those with severe dementia, appears to be feasible, safe, and of potential utility,” said Vahia. “Our preliminary results are a first step in developing much-needed empirical data for clinicians and caregivers on how to use technology such as tablets as tools to enhance care and also for app developers working to serve the technologic needs of this population.”

    “Use of Tablet Devices in the Management of Agitation Among Inpatients with Dementia: An Open Label Study” was recently published in the online version of The American Journal of Geriatric Psychiatry. This research builds upon previous studies demonstrating that art, music, and other similar therapies can effectively reduce symptoms of dementia without medication. By using tablet devices to employ these therapies, however, patients and providers also benefit from a computer’s inherent flexibility.

    “The biggest advantage is versatility,” said Vahia. “We know that art therapy can work, music therapy can work. The tablet, however, gives you the option of switching from one app to another easily, modifying the therapy seamlessly to suit the individual. You don’t need to invest in new equipment or infrastructure.”

    Researchers loaded a menu of 70 apps onto the tablets for the study. The apps were freely available on iTunes and varied greatly in their cognitive complexity — from an app that displayed puppy photos to one that featured Sudoku puzzles.

    The researchers found that tablet use was safe for every patient, regardless of the severity of their dementia, and that with proper supervision and training, the engagement rate with the devices was nearly 100 percent. The study also found that the tablets demonstrated significant effectiveness in reducing symptoms of agitation, particularly — but not exclusively — among patients with milder forms of dementia.

    Vahia cited several examples of the tablet’s potential to improve a patient’s condition. One particular patient, who only spoke Romanian, was very withdrawn and irritable, and medications were ineffective in controlling his symptoms.

    “We started showing him Romanian video clips on YouTube, and his behavior changed dramatically and instantaneously,” said Vahia. “His mood improved. He became more interactive. He and his medical support team also started using a translation app so that staff could ask him simple questions in Romanian, facilitating increased interaction. These significant improvements are a clear testament of the tablet’s potential as a clinical tool.”

    Based on such promising outcomes, the Geriatric Psychiatry Outpatient Services clinical team is expanding the use of tablet devices as a means to control agitation in dementia patients at McLean. This will allow researchers to develop more robust data and expand the scope of the study, including a focus on specific clinical factors that may impact how patients with dementia engage with and respond to apps.


  5. Losing sleep over discrimination? ‘everyday discrimination’ may contribute to sleep problems

    January 6, 2017 by Ashley

    From the Wolters Kluwer Health: Lippincott Williams and Wilkins media release:

    People who perceive more discrimination in daily life have higher rates of sleep problems, based on both subjective and objective measures, reports a study in Psychosomatic Medicine: Journal of Biobehavioral Medicine, the official journal of the American Psychosomatic Society. The journal is published by Wolters Kluwer.

    “Discrimination is an important factor associated with sleep measures in middle-aged adults,” according to the report by Sherry Owens, PhD, of West Virginia University, Morgantown, and colleagues. The results add to previous research suggesting that discrimination and chronic stress may lead to sleep difficulties and increased health risks.

    Discrimination Related to Both Objective and Subjective Sleep Problems

    The study included 441 adults from a nationwide study of health and well-being in middle age and beyond (the MIDUS Study). The participants’ average age was 47 years; about one-third were of non-white race/ethnicity. Complete data were available for 361 participants.

    Participants wore an activity monitor device for one week to gather data on objective sleep measures — for example, sleep efficiency, calculated as the percentage of time spent in bed that the person was asleep. They also completed subjective sleep ratings — for example, how often they had sleep problems.

    Perceived experiences of discrimination were assessed using a validated “Everyday Discrimination Scale.” For example, subjects were asked how often they were treated with less courtesy or respect than others, or how often they were insulted or harassed.

    Discrimination scores were analyzed for association with the objective and subjective sleep measures. Objective measures indicated that about one-third of participants had poor sleep efficiency. Subjectively, one-half of subjects rated themselves as having poor sleep quality.

    Participants who perceived more discrimination had increased sleep problems, after adjustment for demographic, lifestyle, and health factors. Higher discrimination scores were associated with 12 percent higher odds of poor sleep efficiency and a nine percent increase in the odds of poor sleep quality. Discrimination was also related to (objective) time spent awake after falling asleep and (subjective) overall sleep difficulties.

    Non-white subjects had nearly four times the odds of poor sleep efficiency. Otherwise, all differences in sleep measures between white and non-white subjects were related to discrimination.

    Older participants and men were more likely to have some types of sleep problems. Age, sex, and mental/physical health factors explained only a small proportion of the effects of discrimination.

    Previous studies have suggested that racial/ethnic minorities have worse sleep quality. Inadequate sleep is associated with adverse health outcomes, including increased cardiovascular risks and increased mortality. These consequences of poor sleep may account for some of racial/ethnic variation in health outcomes — possibly reflecting inadequate recovery from chronic daily stressors.

    While poor sleep has previously been linked to higher perceived discrimination, the new study is the first to look at how discrimination affects both objective and subjective sleep measures. “The findings support the model that discrimination acts as a stressor than can disrupt subjective and objective sleep,” Dr. Owens and coauthors write.

    The researchers call for further study to confirm and clarify the implications of their findings. Meanwhile, they believe the study adds a “finer resolution” to previous knowledge the relationship between discrimination and sleep — and suggests a possible “causal pathway” connecting chronic discrimination to sleep problems, and thus to increased health risks.


  6. New biomarker is higher in suicide attempters and associated with stress response

    December 14, 2016 by Ashley

    From the Lund University media release:

    debt stressResearchers at Lund and Malmö universities in Sweden have measured a biomarker in cell-free blood plasma which can be linked to an overactive stress system in suicidal individuals. This biomarker can hopefully be used in future psychiatric studies.

    “We don’t expect the marker to be able to predict who will try to commit suicide, but it may serve as a biological marker indicating greater stress exposure in vulnerable people suffering from various psychiatric conditions such as anxiety and depression. We would like to test the marker in future psychiatric studies and see how it is affected by, for example, lifestyle interventions, psychotherapy and pharmacological treatment,” says Daniel Lindqvist, associate professor of experimental psychiatry at Lund University and psychiatry resident at Psykiatri Skåne.

    The researchers compared 37 patients who had been hospitalized at a psychiatric clinic after attempting suicide with an equal number of healthy control subjects. About 70 per cent of both groups were female, and the average age of the patients was approximately 40.

    Compared to the healthy control subjects, the suicidal patients had strikingly increased levels of mitochondrial DNA in their cell-free blood plasma.

    The researchers also found that the large amount of mitochondrial DNA in the plasma was linked to higher levels of cortisol in the blood. Cortisol is an important hormone in the body’s stress system and high levels of cortisol, which have been found in depressed and suicidal patients in previous studies, are a sign of an overactive stress system.

    Previous studies have shown that depressed individuals have an increased level of mitochondrial DNA in their immune cells and that this is linked to stressful life events. Furthermore, studies on animals have shown that increased stress and cortisol levels are linked to higher mitochondrial DNA, but this is the first study to be tested on psychiatric patients.

    “We believe the increased levels in suicidal patients are due to their exposure to severe stress for longer periods than the healthy subjects we compared them to. An increased level of cortisol can cause the body’s cells to malfunction, which in turn contributes to increased levels of cell-free mitochondrial DNA in the blood,” says Lars Ohlsson, senior lecturer at Malmö University.

    “The amount of mitochondrial DNA in cell-free plasma is a new and interesting marker of stress that can be used in future psychiatric studies, but the results have to be replicated in other groups of patients as well. A key question will be how the biomarker changes over time in connection with the patient’s symptoms improving or deteriorating,” says Åsa Westrin, associate professor of clinical psychiatry at Lund University and senior physician at Psykiatri Skåne.


  7. Common probiotics can reduce stress levels, lessen anxiety

    November 28, 2016 by Ashley

    From the University of Missouri media release:

    probiotics gut floraProbiotics, or beneficial live bacteria that are introduced into the body, have become increasingly popular as a way to improve health and well-being.

    Previous studies have shown a direct correlation between gut microbes and the central nervous system. Now, researchers at the University of Missouri, using a zebrafish model, determined that a common probiotic sold in supplements and yogurt can decrease stress-related behavior and anxiety. Studying how gut bacteria affect behavior in zebrafish could lead to a better understanding of how probiotics may affect the central nervous system in humans. Their results recently were published in Scientific Reports a journal of Nature.

    “Zebrafish are an emerging model species for neurobehavioral studies and their use is well-established in drug-screening,” said Aaron Ericsson, director of the MU Metagenomics Center and a research assistant professor in the Department of Veterinary Pathobiology. “Our study has shown that simple probiotics that we normally use to keep our digestive tract in sync, could be beneficial to reducing our stress levels as well.”

    In a series of studies, researchers tested how zebrafish behaved after doses of Lactobacillus plantarum, a common bacteria found in yogurt and probiotic supplements. In the first study, scientists added the bacteria to certain tanks housing zebrafish; other tanks of zebrafish received no probiotics. Then, the researchers introduced environmental stressors to both groups, such as draining small amounts of water from the tank and overcrowding.

    “Each day we introduced a different stressor — tests that are validated by other researchers and cause higher anxiety among zebrafish,” said Elizabeth Bryda, professor of veterinary pathobiology in the MU College of Veterinary Medicine. “These are common environmental stress patterns, such as isolation stress and temperature change, so it made the tests relevant to humans as well.”

    By analyzing the gene pathways of both groups of fish, the research team found that zebrafish that were given the supplements showed a reduction in the metabolic pathways associated with stress.

    “By measuring the genes associated with stress and anxiety, our tests were able to predict how this common probiotic is able to benefit behavioral responses in these fish,” said Daniel Davis, assistant director of the MU Animal Modeling Core. “Essentially, bacteria in the gut altered the gene expression associated with stress- and anxiety-related pathways in the fish allowing for increased signaling of particular neurotransmitters.”

    To test their theory further, the researchers measured the movements of fish in their tanks using sophisticated computer measuring and imaging tools. Previous studies of fish behavior have found that fish that are stressed tend to spend more time at the bottom of their tanks. Once the fish were administered probiotics, they tended to spend more time toward the top of the tanks — the change in behavior indicating they were less stressed or less anxious.

    “Using zebrafish, we’ve developed a relatively inexpensive platform for testing of other species of bacteria and probiotics and their potential benefit on different systems of the body,” Ericsson said.

     


  8. Stress and obesity biologically linked

    October 11, 2016 by Ashley

    From the Hebrew University of Jerusalem media release:

    obesityMetabolic and anxiety-related disorders both pose a significant healthcare burden, and are in the spotlight of contemporary research and therapeutic efforts. Although intuitively we assume that these two phenomena overlap, the link has not been proven scientifically.

    Now, a team of researchers from the Hebrew University of Jerusalem, headed by Prof. Hermona Soreq from the Edmond and Lily Safra Center for Brain Sciences and the Department of Biological Chemistry at the Faculty of Mathematics and Sciences, revealed the molecular elements that bridge anxiety and metabolism — a type of microRNA that influences shared biological mechanisms.

    “We already know that there is a connection between body and mind, between the physical and the emotional, and studies show that psychological trauma affects the activity of many genes. Our previous research found a link between microRNA and stressful situations — stress and anxiety generate an inflammatory response and dramatically increase the expression levels of microRNA regulators of inflammation in both the brain and the gut, for example the situation of patients with Crohn’s disease may get worse under psychological stress, “says Prof. Soreq.

    “In the present study, we added obesity to the equation. We revealed that some anxiety-induced microRNA are not only capable of suppressing inflammation but can also potentiate metabolic syndrome-related processes. We also found that their expression level is different in diverse tissues and cells, depending on heredity and exposure to stressful situations,” explains Prof. Soreq.

    The family of microRNA genes is part of the human genome, which was considered until not too long ago as “junk-DNA.” However, microRNAs are now known to fulfill an important role in regulating the production process of proteins by other genes. These tiny RNA molecules, which are one percent of the average size of a protein-coding gene, act as suppressors of inflammation and are able to halt the production of proteins.

    The research paper, published in the journal Trends in Molecular Medicine, details the evidence linking microRNA pathways, which share regulatory networks in metabolic and anxiety-related conditions. In particular, microRNAs involved in these disorders include regulators of acetylcholine signaling in the nervous system and their accompanying molecular machinery.

    Metabolic disorders, such as abdominal obesity and diabetes, have become a global epidemic. In the USA, the prevalence of metabolic syndrome is as high as 35 percent. In other countries, such as Austria, Denmark and Ireland it affects 20-25 percent of the population.

    Anxiety disorders are harder to quantify than metabolic ones. They include obsessive-compulsive disorder (OCD), post-traumatic stress disorder (PTSD) and phobia. The full burden of the anxiety spectrum is difficult to assess, due to under-diagnosis and poorly defined pathophysiological processes.

    This newly revealed link offers novel opportunities for innovative diagnoses and treatment of both metabolic and anxiety-related phenomena.

    “The discovery has a diagnostic value and practical implications, because the activity of microRNAs can be manipulated by DNA-based drugs,” explains Prof. Soreq. “It also offers an opportunity to reclassify ‘healthy’ and ‘unhealthy’ anxiety and metabolic-prone states, and inform putative strategies to treat these disorders.”

     


  9. How workplace stress contributes to cardiovascular disease

    September 21, 2016 by Ashley

    From the University of California, Irvine media release:

    stressed seniorUniversity of California, Irvine and SUNY Downstate Medical Center researchers have created a model illustrating how economic globalization may create stressful employment factors in high-income countries contributing to the worldwide epidemic of cardiovascular disease.

    Dr. Peter Schnall and Marnie Dobson with UCI and Dr. Paul Landsbergis with SUNY Downstate published their findings online in the current edition of the International Journal of Health Services in the article titled “Globalization, Work and Cardiovascular Disease.”

    Cardiovascular disease, a global epidemic, is responsible for about 30 percent of all deaths worldwide. While mortality rates from CVD have been mostly declining in the advanced industrialized nations, some risk factors — including hypertension, obesity, and diabetes — have been on the increase everywhere. Researchers investigating the social causes of CVD have produced a robust body of evidence documenting the effect of the work environment, including through the mechanisms of psychosocial job stressors. These stressors can produce chronic biologic responses like hypertension and promote unhealthy behaviors, which increase CVD risk.

    The researchers also offer a theoretical model that illustrates how economic globalization influences the labor market and work organization in high-income countries, which in turn exacerbates job characteristics, such as unreasonable demands, low job control, effort-reward imbalance, job insecurity and long hours.

    “Given the high costs of medical treatment and the economic impact on employers and society of ill health, lost productivity, and sickness absence, it is in the interest of all to seriously consider improving work organization,” said Landsbergis, an associate professor in the Department of Environmental and Occupational Health Sciences in the School of Public Health at SUNY Downstate.

    The authors make the following recommendations:

    • Implement national surveillance of occupations, industries and workplaces to identify elevated levels of hazardous work characteristics;
    • Pass regulations and laws limiting psychosocial stressors on the job;
    • Establish upper limits of weekly and yearly work hours (to reduce CVD risk);
    • Mandate vacation time for all employees to facilitate recovery;
    • Pass regulations to mandate a “living wage” that provides sufficient support so that workers are not forced to work excessively long hours;
    • And pass legislation that increases the economic security of precarious workers.

    “We conclude from more than 30 years of epidemiological research that CVD is a disease of modern industrial society and not the natural result of aging,” said Schnall, who is with UCI’s Center for Occupational and Environmental Health and a clinical professor of medicine and public health. “It is related to forms of production that emerged with industrialization and that have expanded with economic globalization: long work hours, repetitive work, high demands, lack of control, long hours, and job insecurity.”

    Global economic policies and the rise of the new flexible labor market have caused an increase in precarious employment in advanced industrialized countries,” added Dobson, an assistant adjunct professor in Center for Occupational and Environmental Health. “These work stressors in turn contribute to CVD risk factors such as obesity, diabetes and high blood pressure.””

     


  10. No sweet surrender: Glucose actually enhances self-control, study shows

    June 7, 2016 by Ashley

    From the Taylor & Francis media release:

    blueberries blackberriesIn the age of the ‘sugar tax’, good news about glucose is hard to come by. But an Australian scientist has just proposed a new understanding of the established link between the sweet stuff and improved .

    As Neil Levy, from Macquarie University, explains in the journal Philosophical Psychology, the current ‘ego depletion’ model of the link between glucose and self-control holds that self-control is a depletable resource. Or put another way, glucose is the fuel for the engine of self-control.

    But Dr Levy isn’t convinced. After examining all the available evidence, he proposes a rival ‘opportunity costs’ model. Glucose isn’t a ‘fuel’ to support self-control, he suggests, but a signal of environmental quality. He explains that, “a resource-poor environment is one in which it is relatively urgent to pursue shorter-sooner rewards; a resource-rich environment is one in which there is little urgency.”

    [Glucose] is a signal that the environment is such that there is relatively less urgency to pursue [smaller sooner] rewards, and that strategies aimed at securing [larger later] rewards are likely to be relatively more successful.” As Levy explains, when people in a resource-rich environment are less sensitive to ‘competing rewards’, they tend to work longer at tasks for which the payoff or reward is delayed: the very definition of self-control.

    “The opportunity costs of allocating attentional and cognitive resources … to a particular task are relatively low; therefore, the subject persists longer or performs better at the task,” he writes. “The subject persists longer because the subject continues to deploy resources without shifting them; the subject performs better because the subject allocates proportionally more resources to the task, as a consequence of not needing to devote resources to scouring for competing opportunities.” Despite his commitment to his theory, Levy acknowledges that glucose might only be one signal of environmental richness. “Any cue that signals a lack of urgency to pursue immediate reward should be expected to have the same effect,” he observes.

    It’s also unlikely that sensing glucose alone would be enough for the body to change its strategy; it may be the case that the body picks up on glucose only when other signals of poverty, conflict or instability are absent. “It is not glucose per se that constitutes the signal: it is glucose correlated with the absence of cues indicating the need to pursue it immediately,” he concludes.

    Dr Levy acknowledges that his theory needs further exploration — but when the experiments involve glucose, he’s unlikely to have any shortage of volunteers.