By: Jane Kumdrot
Not scientifically reviewed by Dr. Eeks
Stress is usually discussed as an emotional experience. Yet, from a biological perspective, stress is essentially a survival mechanism. The human stress response has evolved to help people react rapidly to threats. By doing so, it mobilizes energy, increases alertness, and priortize immediate survival.
It is a highly effective response in a world where threats were physical and time-limited, such asd escaping predators, for example.
But modern life has a different set of stress factors that are not necessarily physical: Deadlines, financial worries, social pressure, work-related demands, etc. However, for the brain and the nervous system, these experiences are processed following the same physiological patterns as those used by our prehistoric ancestors.
Naturally, it’s worth noting that acute stress can be adaptive. However, prolonged activation of stress pathways is likely to influence multiple aspects of physical and cognitive health.
Stress Response Designed for Short-Term Survival
The body’s stress response is primarily coordinated through the autonomic nervous system and the HPA (hypothalamic-pituitary-adrenal) axis. The fight-or-flight response is triggered by the sympathetic nervous system when a threat is perceived.
The response initiates the release of stress hormones, such as adrenaline and cortisol. Additionally, the body undergoes several physiological changes at the same time. You may notice:
- Your heart rate increases
- Your breathing becomes faster
- Your attention and vigilance increase
- Blood flow is redirected toward muscles (either for fight or flight)
- Blood glucose rises to provide energy (so you can respond to the threat)
These reactions are beneficial in the event of a short-term situation that requires immediate action. Acute stress is designed to improve reaction times and increase your performance during a demanding situation.
Human biology has evolved around intermittent threats. But modern stressors can persist for extended periods, which, in turn, sustains the activation of the stress response.
What Happens When Stress Pathways Remain Activated?
Short-term stress and chronic stress don’t affect the body in the same way.
With short-term stress, cortisol levels rise during the period of stress and return to baseline once the perceived threat has passed. With chronic stress, this process is disrupted, and the cortisol levels don’t return to baseline.
Persistent activation of the stress pathways impacts the body and the brain. This translates into disrupted sleep patterns, fatigue, altered immune function, increased inflammation, and fatigue, etc. The HPA axis also appears to play a central role, as chronic activation risks altering communication between the brain regions that are involved in emotional regulation, decision-making, and memory processing.
Stress Can Affect Memory and Cognitive Function
The hippocampus is frequently associated with stress research. It plays a role in learning, memory formation, and information processing.
According to studies, prolonged exposure to high stress hormone levels may have an influence on the hippocampus function and structure. There is also a correlation between chronic stress and reduced neurogenesis, aka fewer new neurons are formed under chronic stress.
As a result, these changes can contribute to symptoms, such as forgetfulness, reduced concentration, slow information processing, and issues retaining new information. For researchers, there may be an important link between high stress and cognitive decline, particularly whether long-term exposure to stress may influence biological pathways associated with cognitive changes and dementia.
While stress may not cause dementia, it can cause symptoms that are frequently associated with a decline typically seen with Alzheimer’s disease. While this may lead to Alzheimer’s being overdiagnosed, there is no doubt that the symptoms are real, even if they may be mistaken for brain degeneration diseases.
Why Emotional Stress Can Activate the Physical Threat System
Chronic stress can feel physically overwhelming because the brain doesn’t make the distinction between physical and psychological threats. The brain region involved in threat detection and emotional processing, the amygdala, responds to perceived danger, whether the danger is physical or not.
So, from a biological point of view, the brain makes no difference between being chased by a predator and any of modern-day stressors like social rejection, workplace conflict, ongoing family issues, financial uncertainty, etc.
This means that even though these situations may not require immediate physical action, they activate the same neural pathways that are connected to survival responses.
As such, the more these pathways are activated, the more persistent feelings of tension (aka alertness) and hypervigilance become, despite the absence of immediate, physical danger.
The Connection Between Chronic Stress and Anxiety
Stress and anxiety are often used interchangeably, but they do not refer to the same mental and emotional state.
Stress is the body’s response to a specific demand or challenge. Anxiety is the persistent anticipation of a future threat, even when there is no immediate stressor.
So, a prolonged stress response is not necessarily anxiety. But the prolonged activation of stress pathways may influence how the brain interprets potential danger. So, the brain becomes more sensitive to stress signals and starts pre-identifying situations as a threat, even without objective danger.
While this is the brain’s way of protecting itself, it creates a heightened state of alertness where different worst-case scenarios are constantly played and applied to current and future situations. Anxiety symptoms tend to appear as well.
Can Stress Responses Be Modified?
Neuroplasticity research suggests that the brain is able to adapt throughout life. So, it would make sense to think of neural pathways linked to stress response as not permanently fixed.
Interventions in the context of stress research can include different activities to help reframe the stress response. These can include cognitive behavior strategies, sleep optimization, regular physical activities, and structural mental health interventions. Especially for individuals who experience persistent and disruptive symptoms, dedicated approaches such as outpatient anxiety treatment can bring the structured support needed to improve both symptoms and the brain’s response.
These treatment approaches can help identify stress patterns and their maladaptive responses, so the individual learns to reduce physiological and psychological distress and to cope better with perceived threats.
The human stress response has evolved to protect survival under threatening conditions. Despite being highly effective, its prolonged activation may affect cognitive, physical, and mental health in dramatic ways.
But it is important to understand that this isn’t necessarily caused by a malfunctioning system. Instead, the biological systems are functioning exactly like they are designed to do. The challenge lies in the fact that the modern pressure and hectic pace can make it seem like the threat is never going away.