The Bright Side of Stress?
Stress is a necessary human experience that keeps us alive.[1] It can be defined by the physical and mental responses we use to combat stressors experienced in our lives, such as threatening situations, insecurity, a tumultuous relationship or academic and work responsibilities.[2] We learn from previous stressors (e.g., avoiding sketchy alleyways we know of, or the signs of “red flags” in a relationship.) These adaptations are how short-term stress can beneficially inform our memory and subsequent learning. Stress-induced fears, anxieties and physiological signals cause us to react to danger or threats so that we know how to avoid a stressor again.
When the brain processes an imminent stressor, the sympathetic nervous system and hypothalamic-pituitary-adrenocortical (HPA) axis react to release adrenaline and glucocorticoids.[3] The sympathetic nervous system activates physiological responses for a fight or flight response. For example, pupils dilate and heart rate increases. The HPA axis regulates the stress response through structures such as the hypothalamus and hippocampus, an important structure for memory, via steroid hormones like cortisol.[4] By a negative feedback loop, the hippocampus’ cortical receptors are activated for the memory and biological learning of a stressful event.[5] As a result, memory is improved following an acute stress response so that our learning is improved for future similar stressful situations.[6,7]
When Stress Becomes Problematic
While research indicates that short-term or acute stress can promote behavioral adaptations and improve spatial memory, in the same study by Lin et al. (2022), prolonged durations of stress led to behavioral and cognitive impairment in animal models.[8] Relatedly, in humans, long periods of stressful life events lead to cognitive and memory declines in older adults.[9] Additionally, prolonged (i.e., chronic) stress can increase risk of disease and mortality.[10,11]
Chronic stress causes the body to be constantly out of balance (i.e., allostasis) in response to trying to restore balance (i.e., homeostasis) through energy expenditure.[12] The cumulatively created effect of chronic stress is referred to as allostatic load (when allostasis is repeatedly activated with a lack of adaptation or conclusion of the stress response.)[13] These chronic and repeated stress responses increase cortisol, which negatively affect components of memory (like navigation and long-term memory retention), and structurally damages neurons necessary for memory.[14,15] This leads the human body to be in a constant state of neurological disruption that is not restored, resulting in negative impacts on one’s memory.[16-22]
Despite these negative health impacts, chronic stress remains an extremely common experience. According to the American Institute of Stress (2022), 94% of American workers say they are stressed at work while 55% of Americans report that they are stressed during any given day.[23] While some degree of stress in life is vital, an allostatic load can decrease well-being and cognition, and should be reduced to promote one’s health and overall life.
What Chronic Stress Looks Like
Chronic stress has particularly negative effects on the hippocampus (related to forming and sustaining memory), amygdala (related to emotional regulation) and neurons in the prefrontal cortex (related to problem-solving and planning).[24] Duman (2004) notes that by using physical restraints on rats, chronic stress was found to decrease neuron length and branching in the hippocampus.[25] Furthermore, increased glucocorticoid circulation leads to decreased neural plasticity (i.e., when neurons adapt and connect to process or establish information), and decreased growth of neurons in the hippocampus.[26] Brain-derived neurotrophic factor (BDNF) signaling, a marker of neural plasticity, is also reduced in the prefrontal cortex and hippocampus following chronic stress.[27]
Chronic stress essentially impairs memory consolidation and retrieval, making reactivating and forming new information more difficult and less frequent.[28] Memory for spatial and navigating information was found to be impaired due to chronic stress, as well.[29] The body’s homeostatic regulation in response to a prolonged stressor additionally causes chronic neuroinflammation.[30] For these reasons, allostatic load leads to an increased risk of developing certain disorders such as post-traumatic stress disorder (PTSD), depression and neurodegeneration; these risks increase with age and cortisol levels.[31]
Signs of chronic stress include:[32-34]
Emotional dysregulation
Decreased memory for events, general knowledge and navigation
Social withdrawal
Depressive symptoms
Increased anxiety and constant worrying
Fatigue or low energy
Immune system dysregulation and impaired disease resistance
High blood pressure
When chronic stress becomes persistently life-impairing, it can be a significant factor in several disorders, such as those involving anxiety, emotional disruption and cognitive problems. Stress-related cognitive impairment is found in several conditions and disorders:
PTSD symptom severity is associated with cognitive decline.[35]
In middle age, those with depression and high allostatic load have a higher risk of cognitive decline.[37]
Childhood psychological stress (i.e., childhood poverty) is associated with a greater risk for anxiety-related symptoms and allostatic load in adolescence and adulthood with intensity relating to the duration of the allostatic load.[38]
Impaired memory in depressed individuals is often attributed to chronic stress and its duration.[39]
Those with anxiety and mood disorders tend to experience psychological stress for lengthy periods. This is why high allostatic load is a factor for memory problems as the brain’s hippocampal neurons atrophy or degenerate and plasticity is disrupted by exhausted homeostatic energy expenditure.
Perceptive Differences
While individuals with mood or anxiety disorders are more vulnerable to chronic stress and memory impairment, stress responses can still vary by person and are not exclusive to those who experience such disorders. Chronic stress itself is also not a disorder, but a comorbid risk factor for memory impairment that can look different for everyone.
Internal beliefs vary per individual and are subjective, causing certain situations to be stressful to some and not to others, and leading to varied effects on memory. For example, students’ perceived high stress is found to be partially reliant on low self-efficacy (i.e., belief in self-success) and high emotional attention.[40] Additionally, high stress and cortisol levels lead to worsened memory performance such as declarative memory (i.e., memory for general knowledge and events), and cortisol is found to be in higher levels in females than males.[41,42] This is because cortisol levels are impacted by ovarian hormones such as estrogen.[43] Therefore, higher baseline cortisol levels may lead to high cortisol release when responding to stress.[44] For such reasons, cortisol administration is a way of inducing depression in animal models in addition to physical and social stressors due to chronic exposure. Other individual differences (such as age) may impact perceived stress as in older adults; egocentric stressors (e.g., self-health and financial stressors) were found to be detrimental to cognitive functioning as opposed to non-egocentric stressors.[45]
Societal stressors may also impact the rate and intensity of the stressors that different groups face. For example, individuals of a sexual minority often experience increased impairment in psychosocial adaptation and overall quality of life likely due to negative stereotyping or stigma consciousness.[46] Menhinick & Sanders (2023) note that fear of violence is also an imminent physical stressor that many LGBTQ+ individuals and racial minorities experience, which can induce chronic stress, depression and PTSD.[47]
Solutions to Mitigate and Overcome Chronic Stress
Several methods can be employed to tackle chronic stress. A social-psychological approach may look at the stressors that arise from social norms. From such a perspective, effortful social change can alleviate minority stress and threats, which removes the fault from the individual experiencing the neurological effects of stressors and targets the creation of the stressors themselves, such as violence and microaggressions arising from biases.[48]
In terms of regenerating neurological functioning, Hernandez & Brinton (2022) found that allopregnanolone (a neurosteroid) may activate the GABA-chloride complex and can help to promote neurogenesis or the formation of neurons in the brain.[49] Relating to diet, Szala-Rycaj et al. (2023) found that chicory root insulin and topinambur powder, when supplemented long-term, can alleviate anxiety and cognitive disorder-like symptoms that were induced through chronic stress in animal models.[50] Additionally, Duman (2004) notes that antidepressants such as selective serotonin reuptake inhibitors (SSRIs) have been shown to reflect a reversal of neuron atrophy in the hippocampus and promote neural plasticity as well.[51] Note: it is important not to start or stop taking any medications or supplements without first discussing them with your physician and/or pharmacist.
Several evidence-based psychotherapies are effective at preventing and overcoming the effects of chronic stress. Acceptance and Commitment Therapy (ACT) is an approach that focuses on the awareness of mental states and thoughts with particular effectiveness for mood and anxiety disorders.[52] Mindfulness-Based Therapy (MBT) additionally reduces stress through attention to physical experiences and meditation.[53] This modality directly targets psychological stress reduction by promoting relaxation and building mindfulness skills. Cognitive Behavioral Therapy (CBT) is effective in treating stress-related disorders such as PTSD, anxiety, and depression by utilizing cognitive-restructuring of negatively-formed or maladaptive thoughts and behaviors that cause stress.[54]
Due to the variety of potential stressors that one can experience and the individuality of perceived stress responses, it is possible that a combination of stressor-targeting and personal psychological support is necessary for both avoiding chronic stress and memory impairment, in addition to recovering from chronic stress. In everyday life, acute stress is beneficial for memory and the body, but chronic stress that takes both physical and psychological forms should be avoided as much as possible. Lowering chronic stress may further be promoted through prioritizing safety, relaxation, nutrition, time in nature, engaging in therapy to find ways to cope with stressors, and decreasing time on social media.[55]
Moreover, this responsibility to avoid chronic stress is not always carried solely by the individual but is also held by a network of people that socially impact each other’s lives every day. In order to reduce the negative memory and health effects of chronic stress, both the individual and the environment by which they interact should be addressed. Stress and memory research continues to rapidly evolve, and may eventually be able to determine how to quantify, possibly by time and neural information, dangerous amounts of allostatic load on the brain and the processes of memory.
If one is experiencing prolonged or chronic stress that is impacting daily life and overall well-being, please reach out to a licensed mental health professional (e.g., a psychotherapist, psychologist or psychiatrist) for guidance and support.
Contributed by: Phoebe Elliott
Editor: Jennifer (Ghahari) Smith, Ph.D.
References
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5 Ibid.
6 Lenart-Bugla et al. (2022)
7 Peavy et al. (2009)
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27 Ibid.
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29 Akan et al. (2023)
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31 Palego, L., Giannaccini, G., & Betti, L. (2021). Neuroendocrine response to psychosocial stressors, inflammation mediators and brain-periphery pathways of adaptation. Central Nervous System Agents in Medicinal Chemistry, 21(1), 2-19. doi:10.2174/1871524920999201214231243
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35 Prieto et al. (2023)
36 Ibid.
37 Perlman et al. (2022)
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