This Is Your Brain on Stress
Ground-breaking research on neuroplasticity
Posted Jun 28, 2015
Hey man, don’t stress me out! We’ve all experienced stress from threats (physical, social, and financial), fears, uncertainty, and cognitive dissonance (the gap between what we think and what we do—I don’t like when people push their way into a line, but I did it because I needed to pick up my daughter at school—this stressed me out).
Unfortunately, many stressors aren’t perceived as positive challenges—good stress—but as negative threats—bad stress. Trying to cope with significant events such as divorce, job, school, new house, financial hardships, conflicts, health issues, and death often result in persistent stress. The effects of chronic bad stress are well known. It’s been estimated that between 75 - 90% of all physician visits are for stress-related ailments and complaints. Your nervous system reacts by continuing to pump out excess stress hormones that wear out the body’s reserves and leave you feeling depleted. Your immune system is compromised, leaving you more prone to infections. Your blood pressure is elevated; you have an upset stomach, headache, diabetes, asthma, heart disease, and arthritis.
How about your mind? We get depressed, fatigued, anxious, panicked, and burnt out. Most organs are adversely affected by chronic stress. Your brain is no exception. Dr. Cheryl Conrad, Professor of Psychology at Arizona State University, studies the effects of stress on the brain. Specifically, she is interested in how stress influences brain plasticity—the brain’s ability to morph. Dr. Conrad believes that while “the stress response is key to organism survival,” chronic activation has significant negative consequences on brain plasticity and resilience. Reduced brain plasticity may be a factor in depression, anxiety, PTSD and even Alzheimer’s disease. By studying stress and neuroplasticity, Dr. Conrad hopes to uncover how we become resilient. She is also interested in elucidating the mechanisms by which chronic stress alters neuronal morphology and function, and the factors that influence recovery and resilience.
Here is your brain while exposed to stress—some amazing and important findings:
- Chronic stress alters many neurochemicals and neurohormones such as increasing the excitatory neurotransmitter—glutamate.
- Brain regions respond differently to stress.
- The hippocampus, part of the limbic system and intimately involved in learning and memory, is very sensitive to stressors. Conrad’s lab looked at individual hippocampal neurons and found that chronic stress resulted in the retraction and shrinking of dendritic arbors—the receiving end of information for neurons. The hippocampus is involved in shutting down the steroid part of the stress response and lesions in the hippocampus lead to hypersecretion of stress steroids. Consequently, under chronic stress, the hippocampal remodeling may contribute to a never-ending cycle of stress responses.
- The consequences of the early effects of chronic stress on spatial memory are potentially critical: failure to learn locations could impact survival in the wild or performance in society.
- A chronically stressed individual will acquire an aversive event faster than a non-stressed individual. When a memory is formed, they will resist extinguishing to it. Once they show extinction, they fail to remember the extinction at a later date as if extinction never happened. This is known as impaired recall of fear extinction. Chronic stress impairs the prefrontal cortex and by doing so impedes the recall of fear extinction. Let’s use an example given by Dr. Conrad of a soldier with PTSD. The soldier is under severe stress and exposed to a traumatic experience (a friend getting killed). Back in the states, whenever a car backfires, the veteran reacts violently. With exposure therapy (analogous to extinction in rodents), the veteran might show less and less responses to the backfiring of a vehicle. But then the very next day in another place when a vehicle backfires, the veteran could react robustly as if the exposure therapy did not occur. This is analogous to poor recall of fear extinction. This is why exposure therapy is so challenging.
- Conditions that produce dendritic retraction make those neurons more susceptible to a neurochemical challenge than compared to conditions that do not produce dendritic retraction.
- The amygdala, known for emotional regulation and fear learning, has the opposite response to chronic stress; dendrites become more prominent and robust, predicting a greater likelihood of reacting badly and creating abnormally strong memory formation. Those with a dysregulated amygdala are more likely to go into a rage.
- Even a single incident may increase amygdala size and size gets greater with time.
- The detrimental effects from chronic stress on the hippocampus show evidence of recovery when the stress experience ends. This neuroplasticity suggests that our brains have the capability to recover well from stress.
- Chronic stress impairs hippocampal-mediated spatial learning and memory, which slowly recovers with time following a post-stress period. This neuroplasticity-induced recovery is due, at least in part, to brain-derived neurotrophic factor (BDNF) (Ortiz et al, Eur J. Neuroscience, 2014). BDNF is a protein in the brain, which is intimately involved in growth, differentiation and survival of neurons as well as enhancing synaptogenesis. Chronic stress reduces levels of hippocampal BDNF. In other words, BDNF may be a chemical mediator of resilience—our ability to bounce back after a stressful event.
How do we increase BDNF levels or up-regulate (increase the number of) BDNF receptors?
- Many antidepressants (up-regulate) increase BDNF. Other psychiatric treatments that elevate BDNF levels or activate BDNF receptors include: electroconvulsant therapy (ECT) and vagal nerve stimulation.
- A variety of foods and supplements increase BDNF or prevent decreases during stress such as:
- Mediterranean diet—plant-based foods, whole grains, oils, nuts, legumes, vegetables.
- Fish oil—contain omega-3 fatty acids.
- Ginsenoside - active ingredient in ginseng
- Zinc—dietary mineral and co-factor in many important enzyme reactions
- Hyperoside—found in St. John’s wort
- Curcumin—from the spice, turmeric
- Ferulic acid—found in peanuts, apples, orange, rice, wheat and oats
- Beta-alanine—component of vitamin B5 and dietary supplement
- Flavonols—present in many fruits and vegetables
- Ginkgo biloba—Maidenhair tree, herbal medicine
- Eugenol—essential oil from nutmeg, clove, basil
- Piperine—found in black pepper
- Alpha-linolenic acid—essential omega-3 fatty acid in seeds, nuts and veggie oils
- Suyu-Jiaonang (SYJN)—Chinese herbal formula with 4 herbs
- Polygala tenuifolia (Yuan Zhi)—Chinese herb with memory enhancing properties
- Xiaoyaosan—Chinese herbal medicine
- Danzhi Xiaoyao—Chinese herbal medicine with neuro-immuno-endocrine effects
- Certain types of exercise increase levels of BDNF. This may help explain some of the psychological benefits of exercise to combat stress and the positive correlation of exercise and resilience.
- Music enhances BDNF levels, improves mood and lowers stress
I’m not saying that making more BDNF is the key to removing stress from your life.
I’m saying that Dr. Cheryl Conrad at ASU may be on to something that will help you improve your ability to think, learn and remember and recover faster psychologically after a stressful, traumatic event.
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