Human Studies Of The Prefrontal Cortex
Lower subjective social status, as reflected by a lower self-reported ranking on a âsocial ladderâ, was associated with reduced gray matter volume in the perigenual area of the anterior cingulate cortex . Illustration of 10-point social ladder scale used to assess subjective social status. Overlaid on an anatomical template is a statistical parametric map of color-scaled t-values, which illustrate the pACC area where lower subjective social status was associated with reduced gray matter volume across individuals. Plotted along the y-axis is the standardized gray matter volume values for pACC area profiled in B. Plotted along the x-axis are social ladder rankings from the scale illustrated in A . *P< 0.001. From Gianaros et al. , reprinted with permission.
Emergence Of Sex Differences In Response To Stressors After Puberty
Although the sensitive period for testosterone effects on sexual differentiation is perinatal in rodents, sex differences in response to chronic stressors manifest themselves gradually over the pubertal transition. Demonstration of this was accomplished using a rodent model of chronic restraint stress in juvenile rats daily from postnatal days 20 to 41 . Chronic stress produced depressive-like behavior and significant neuronal remodeling of brain regions likely involved in these behavioral alterations: the hippocampus, PFC, and amygdala. Both chronically stressed males and females exhibited anhedonia, increased locomotion when exposed to novelty, and altered coping strategies when exposed to acute stress. Chronic stress produced shrinkage of dendrites in the hippocampus and PFC and concurrent hypertrophy of dendrites in the amygdala, with a trend for males to show more robust responses than females .
Mindfulness: A Heroic Defence Against Stress
Mindfulness is exceptional in its capacity to control stress and the effectiveness of this ancient practice is seeing it take its place in the mainstream. Everybody can do it. Everybody can make time for it. Heres how it works
As little as one minute a day of concentrated stillness can have a huge effect, but the more you can do, the more the effect will carry through. 15 minutes three times a week will have a profound effect on mental health.
Mindfulness is all about experiencing whats happening in the moment rather than being strapped by the past or worrying about the future . To practice basic mindfulness:
- breathe in for five seconds,
- hold for five seconds,
- breathe out for five seconds.
- while you do this, focus on your sensory experience. What are you experiencing right now?What do you feel against your skin? What smells can you notice? Sounds? Temperature? Whats happening beneath your skin? Bodily sensations? Can you hear your breathing? Feel your heartbeat?
- let other thoughts come and go but the idea is not to hang on to them for too long. Stay as much as you can in the present moment.
Mindfulness can take a bit of practice, especially if your mind is used to racing around on its own. The more you practice, the easier it will become.
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Surprising Ways That Stress Affects Your Brain
Carly Snyder, MD is a reproductive and perinatal psychiatrist who combines traditional psychiatry with integrative medicine-based treatments.
Stress is a familiar and common part of daily life. Stress happens each and every day and comes in a wide variety of forms. It might be the stress of trying to juggle family, work, and school commitments. It might involve issues like health, money, and relationships.
In each instance where we face a potential threat, our minds and bodies go into action, mobilizing to either deal with the issues or avoid the problem .
You have probably heard all about how bad stress is for your mind and body. It can lead to physical symptoms such as headaches and chest pain. It can produce mood problems such as anxiety or sadness. It can even lead to behavioral problems such as outbursts of anger or overeating.
What you might not know is that stress can also have a serious impact on your brain. In the face of stress, your brain goes through a series of reactionssome good and some baddesigned to mobilize and protect itself from potential threats. Sometimes stress can help sharpen the mind and improve the ability to remember details about what is happening.
Stress can have negative effects on the body and brain. Research has found that stress can produce a wide range of negative effects on the brain ranging from contributing to mental illness to actually shrinking the volume of the brain.
What Influences Our Capacity For Coping With Stress
Several factors influence our capacity for coping with stress:
- The presence of a social network
- Our skill and confidence in assessing a complex situation and then developing and evaluating solutions
- Personal variables such as physical health, experience, confidence, anxiety threshold and problem-solving abilities .
Stressful events are a universal part of the human experience. You may or may not be able to change your current situation, but you can take steps to manage the impact these events have on you.
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Translation To Human Amygdala: Mood Disorders And Ptsd
The protective effects of a timed elevation of glucocorticoids in several animal models of traumatic stress have a human counterpart, as both epidemiologic studies and clinical research on patients undergoing cardiovascular surgery indicate that low glucocorticoid levels at the time of trauma increase probability of PTSD symptoms . Moreover, administration of a glucocorticoid within an hour after a traffic accident was reported to reduce subsequent PTSD symptoms .
Amygdala overactivity is also associated with mood disorders and amygdala enlargement is reported in children of chronically depressed mothers . Therapeutically, individuals with a chronic anxiety disorder have been shown to benefit from mindfulness-based stress reduction and when anxiety is reduced there is a reported decrease in amygdala volume .
Functional Consequences Of Structural Remodeling In Hippocampus
CRS for 21 days causes impairments in memory in a radial arm maze and in a Y maze that can be prevented by agents such as Dilantin and the antidepressant tianeptine, which prevent stress-induced remodeling of CA3 dendrites . In another study using a 1-mo chronic variable stress paradigm, stressed rats took longer to train in the initial Morris water maze trial the day after the last stress session, and they also were impaired in learning a new platform location in a probe trial . The effects of chronic stress on both morphology and learning disappeared within 12 wk after cessation of the daily stress regimen , suggesting that it serves an adaptive function and does not constitute damage. This notion, discussed above in relation to the dendritic remodeling during hibernation, is supported by the fact that dominant rats in a social hierarchy have somewhat larger reductions of CA3 dendritic length and branching compared with subordinate rats in the hierarchy, with both groups showing shorter dendrites than rats housed in groups in ordinary cages adrenal size was larger in the subordinate rats .
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D New Insights Into Positive Health And Self
Positive health and self-esteem are two uniquely human-oriented concepts that, nevertheless, have been recently subject to illumination based on the concepts and findings discussed in this review. Having a positive outlook on life and good self-esteem appear to have long-lasting positive health consequences , and good social support has a positive influence to reduce the measures of allostatic overload . Positive affect, assessed by aggregating momentary experiences throughout a working or leisure day, was found to be associated with lower cortisol production and higher heart rate variability , as well as a lower fibrinogen response to a mental stress test .
On the other hand, poor self-esteem has been shown to cause recurrent increases in cortisol levels during a repetition of a public speaking challenge in which those individuals with good self-esteem are able to habituate, i.e., attenuate their cortisol response after the first speech . Furthermore, poor self-esteem and low internal locus of control have been related to 1213% smaller volume of the hippocampus, as well as higher cortisol levels during a mental arithmetic stressor . As noted above in section ii, the elevated cortisol may be both a cause and a result of the smaller hippocampus, which is consistent with the glucocorticoid cascade hypothesis of Sapolsky .
The Buildup Of Stress
While some occasional stress is not problematic, prolonged stress can lead to serious problems.
Psychosocial stress is a major reason for chronic stress, and is especially present in the workplace. It can develop over time when, for example, employees have excessive workloads, feel as though they are not being managed properly or not being rewarded for their efforts.
When chronically stressed, the body creates an excessive amount of cortisol. Instead of all the benefits of the good stress, abnormally high levels of cortisol will have the opposite effect, leaving you unable to focus and extremely tired. It can also lead to physical symptoms such as headaches, weight gain and chest pains, amongst others.
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The Effects Of Stress On The Brain
Life and stress can feel like a package deal but some people are more susceptible to stress than others. The same crisis can cause some to grow and others to break and become sick with illnesses such as depression.
Researchers have shed the light on why.
The answer lies in our genes. The response to stress is determined by a complex interaction between versions of the depression gene and the environment.
The research, published in the Journal of Neuroscience, has found that stressful life events interact with certain genes to change the size of the hippocampus, the part of the brain that processes emotions and transfers new information into long-term memories. An effectively functioning hippocampus is critical for learning.
D Prefrontal Cortex And Amygdala
Acute and repeated stress also cause functional and structural changes in other brain regions such as the prefrontal cortex and amygdala. CRS and chronic immobilization caused dendritic shortening in medial prefrontal cortex but produced dendritic growth in neurons in amygdala , as well as in orbitofrontal cortex . These actions of stress are reminiscent of recent work on experimenter versus self-administered morphine and amphetamine, in which different, and sometimes opposite, effects were seen on dendritic spine density in orbitofrontal cortex, medial prefrontal cortex, and hippocampus CA1 . For example, amphetamine self-administration increased spine density on pyramidal neurons in the medial prefrontal cortex and decreases spine density on orbitofrontal cortex pyramidal neurons .
Regarding the amygdala, chronic stress for 21 days or longer not only impairs hippocampal-dependent cognitive function but it also enhances amygdala-dependent unlearned fear and fear conditioning , which are consistent with the opposite effects of stress on hippocampal and amygdala structure. Chronic stress also increases aggression between animals living in the same cage, and this is likely to reflect another aspect of hyperactivity of the amygdala . Moreover, chronic corticosterone treatment in the drinking water produces an anxiogenic effect in mice , an effect that could be due to the glucocorticoid enhancement of CRF activity in the amygdala .
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Epigenetics Stress And Mood
After its original definition, as the emergence of characteristics of an organism during development that were not evident at earlier stages , epigenetics’ now refers to events above the genome’ that regulate expression of genetic information without altering the DNA sequence. Besides the CpG methylation described above, other mechanisms include histone modifications that repress or activate chromatin unfolding and the actions of non-coding RNAs . Again the hippocampus is providing important information. For example, Reul and colleagues have shown that the forced swimming-induced behavioral immobility response requires histone H3 phospho-acetylation and c-Fos induction in distinct dentate granule neurons through recruitment of the NMDA/ERK/MSK 1/2 pathway .
Another histone mark changed in hippocampus, most prominently in the dentate gyrus, is the dramatic induction by an ARS of trimethylation of lysine 9 on histone H3, which is associated with repression of a number of retrotransposon elements and reduction of the coding and non-coding RNA normally produced by the repressed DNA . This repression is lost with repeated stress, suggesting the possibility that those retrotransposon elements may impair genomic stability under conditions of chronic stress .
Stress Halts The Production Of New Brain Cells
Every day you lose brain cells, but you also have the opportunity to create new ones each day.
Brain-derived neurotrophic factor is a protein thats integral to keeping existing brain cells healthy and stimulating new brain cell formation.
Its often been called fertilizer for the brain.
But cortisol halts the production of BDNF, resulting in the formation of fewer new brain cells.
Lowered levels of BDNF are associated with many brain-related conditions including depression, obsessive-compulsive disorder, schizophrenia, dementia, and Alzheimers disease.
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Stress Can Affect Your Mood
Your brain records things as you perceive them, not as they actually happen. When you are in a stressed survival mode, you become hypersensitive to the external environment and your brain associates everything as a potential danger. In this state, it is unable to judge situations effectively and misinterprets cues and assumes the worst. Consequently, stress makes every external factor appear negative, putting you in a constant defensive mode. This causes abnormal reactions, and over time the brain struggles to readapt and can stay in that negative mode.
Traumatic Effects Of Chronic Stress On The Brain
Chronic stress increases the stress hormone cortisol, affecting brain health and function and putting you at risk for various mood and mental disorders.
Chronic stress is a modern epidemic.
The human body is not designed to be in a state of perpetual stress and continue to stay healthy.
Dr. Pat | Be Brain Fit
Excess cortisol leads to a host of physical health problems including headaches, asthma, immune system dysfunction, weight gain, osteoporosis, digestive disorders, hormone imbalances, cancer, heart disease, hypertension, and diabetes.
Cortisol also takes an equally high toll on your mental health by changing the structure and function of your brain.
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Understanding How Stress Affects The Brain
Professionals working in health and human services or psychology have the opportunity to help others manage their stress effectively and understand how stress affects the brain. Touro University Worldwide offers a variety of fully online degree programs at the bachelors, masters and doctoral level that prepare students for careers in these fields.
D Being Stressed Out: Example Of Sleep Deprivation And Its Consequences
The common experience of being stressed out has as its core the elevation of some of the key systems that lead to allostatic overload: cortisol, sympathetic activity, and proinflammatory cytokines, with a decline in parasympathetic activity. Nowhere is this better illustrated than for poor or inadequate sleep, which is a frequent result of being stressed out. Sleep deprivation produces an allostatic overload that can have deleterious consequences.
Because the brain is the master regulator of the neuroendocrine, autonomic, and immune systems, as well as behavior , alterations in brain function by chronic stress can, therefore, have direct and indirect effects on the cumulative allostatic overload. Reduced sleep duration has been reported to be associated with increased body mass and obesity in the NHANES study . Sleep restriction to 4 h of sleep per night increases blood pressure, decreases parasympathetic tone, increases evening cortisol and insulin levels, and promotes increased appetite, possibly through the elevation of ghrelin, a proappetitive hormone, along with decreased levels of leptin . Moreover, proinflammatory cytokine levels are increased with sleep deprivation, along with decreased performance in tests of psychomotor vigilance, and this has been reported to result from a modest sleep restriction to 6 h/night .
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The Research What They Did
Researchers collected information from healthy participants about any stressful life events theyd been through, such as deaths of loved ones, divorce, unemployment, financial losses, relocations, serious illnesses or accidents.
Genetic analyses were also carried out, as well as scans of the subjects hippocampi.
Effects Of Chronic Glucocorticoid Administration On Morphology And Memory
Chronic corticosterone treatment by injection or by passive administration in the drinking water are both able to cause dendrites to retract in CA3 hippocampus . Moreover, the effects of injected corticosterone are known to be blocked by Dilantin, an inhibitor of ion channels that has antiepileptic effects, a result that is consistent with the evidence that glutamate is involved in remodeling . Yet, there is an important difference between the effects of repeated stress and chronic glucocorticoid exposure, in that chronic corticosterone treatment was reported to reduce the volume fraction occupied by mitochondria in the CA3 region while, as noted earlier, 21 days of CRS increases mitochondrial profiles in mossy fiber terminals . This suggests that somewhat different mechanisms may be involved in effects of CRS and corticosterone in hippocampus, a possibility that is supported by the finding that, while both corticosterone treatment in the drinking water and 21 days of CRS both caused CA3 remodeling when given alone, the combination of CRS plus corticosterone treatment abolished the morphological change . These mechanistic differences remain to be determined.
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What About Positive Stress
On the other hand, positive stress, such as that which is experienced in exciting social situations, can cause the hippocampus to increase in size.
Its our genes that decide whether the same stressful event causes the hippocampus to shrink or enlarge, and therefore whether the stress is good or bad for our brain.
The greater the number of risk genes somebody has, the more likely it is that stressful life events will shrink the hippocampus.
If there are only a small number or none of the risk genes present, the same stressful event can have a positive effect on the anatomy of the brain.