Effects of Chronic Stress on The Nervous System

Stress is a natural part of life, and the human body is designed to handle short-term stressors. That said, chronic stress can wreak havoc on your nervous system and physical health. The impact of stress on the nervous system can be complex and multifaceted. Moreover, individual responses to stress can vary. This article will explore how chronic stress affects your nervous system.

The Nervous System and its Divisions

First, let’s delve into the intricacies of the nervous system and its components. The nervous system is a complex network that communicates information throughout your body. It consists of two main parts:

1.   Central nervous system (CNS) - includes the brain and spinal cord and serves as the command center.
2.  Peripheral nervous system (PNS) - extends throughout and connects the CNS to the rest of your body.

We further divide the PNS into the autonomic and somatic nervous systems. The autonomic nervous system (ANS) involuntarily regulates body functions such as heart rate, blood pressure, digestion, and breathing. It also directly affects your physical response to stress.

The ANS has two components:

1.    Sympathetic nervous system (SNS), responsible for the "fight-or-flight" response
2.   Parasympathetic nervous system (PSNS), for the "rest-and-digest" response

Research shows that long-term tension tends to affect both the CNS and the PNS. We’ll first list the CNS effects, followed by the PNS effects.

Impact of Longstanding Stress on the CNS

Chronic stress can take a heavy toll on your CNS (i.e., your brain and spinal cord). Here are some ways in which prolonged stress can affect the CNS:

1. Structural Changes in the Brain

Persistent stress can cause alterations in the brain structure, particularly in areas such as the hippocampus, prefrontal cortex, and amygdala.

A. Changes in the hippocampus

Hippocampus is the brain region involved in memory, learning, mood regulation, and stress response. Studies reveal that chronic stress can cause the hippocampus to shrink. This can impair its ability to regulate your emotions, store memories, and dampen the stress response.

B. Changes in the prefrontal cortex

The prefrontal cortex (PFC), located at the front of your brain, performs the following main functions:

·       Orchestrates executive functions like problem-solving and decision-making.
·       Responsible for emotional regulation and impulse control.
·       Plays a role in working memory, allowing for mental flexibility.

Hence, stress-induced alterations in the PFC can lead to:

Cognitive deficits: The dendrites of the PFC neurons tend to shrink, medically termed dendritic atrophy. Dendrites are branches of neurons that allow neurons to receive signals from one another. Studies show that this dendritic atrophy disrupts the cortex's functions. It challenges cognitive processes such as attention, working memory, and problem-solving.

Emotional instability: Your ability to manage stress, control negative emotions, and adapt to changing situations becomes daunting, as if navigating a maze with a blindfold. Emotional turbulence is a double whammy, leaving you ill-equipped to tackle stress.

Behavioral changes: These include impulsive or risky behaviors. Your ability to resist temptations, delay gratification, and make rational choices may be compromised. This can have detrimental effects on behavior and daily functioning.

3 ways chronic stress can change you

C. Changes in the Amygdala

The brewing storm in your brain also ignites the amygdala, a region involved in fear and anxiety. In fact, this tiny almond-shaped area is the first to respond during times of stress.

So, what happens when your amygdala perceives a threat? It triggers another region in your brain known as the hypothalamus. This command center stimulates your SNS, releasing stress hormones (epinephrine and cortisol) from the adrenal glands atop your kidneys. Your body rushes with a pounding heart, heightened alertness, and an energy surge - the "fight-or-flight" response in full force.

But the effects don't stop there. Remember how the storm in your brain ignited the amygdala? This hyperactive amygdala further amplifies your sensitivity to stressors. It becomes hyper-alert, scanning for potential threats with increased intensity.

This is how prolonged stress leads to a vicious cycle of stress-related disorders, negatively impacting your mind and body.

2. Mood Disturbances

Intense stress can throw off your balance of neurotransmitters, those tiny messengers that orchestrate your mood. It can lower the curtain on serotonin and dopamine, the conductors of happiness, leading to a melancholic tune of depression.

When exposed to constant pressure, certain hypothalamic neurons also start firing excessively. This undue neuronal firing can spark anhedonia, a disinterest in previously enjoyable activities. Anhedonia is a leading symptom of depression.

Meanwhile, chemicals like noradrenaline and glutamate take the spotlight as the stress response duo. This stirs up an anxious melody that leaves you on edge.

Moreover, stress can manifest as physical symptoms like fatigue, headaches, and muscle tension. These symptoms further add to anxiety and depression.

3. HPA Axis Dysregulation

What is the hypothalamic-pituitary-adrenal (HPA) axis, and how does it work? As the name indicates, it is a network comprising the hypothalamus, the pituitary gland, and the adrenal glands.

You may call the HPA axis the “mastermind system” that governs your body's response to stress. Though not directly a part of the nervous system, it is closely connected to and interacts with your nervous system. Like a vigilant sentinel, the HPA axis stands guard, monitoring your internal and external environment for any signs of threat.

Usually, when stress comes knocking, your HPA axis sets into motion, setting off a defensive cascade of events as follows:

1.            The cascade begins in the hypothalamus, often called the "master gland," as it controls all other endocrine glands in your body.
2.            The hypothalamus signals the small pea-sized pituitary gland, commanding it to release adrenocorticotropic hormone (ACTH).
3.            The ACTH travels through your bloodstream, reaching the adrenal glands.
4.            ACTH signals the adrenal glands to unleash a torrent of stress hormones. Cortisol is the leading player in this hormonal cascade.
5.            Cortisol then surges through your veins, ready to do battle. In the short term, cortisol is a vital ally, helping you stay alert, focused, and energized in adversity.

Yet, when stress becomes a constant companion, the HPA axis falters. Chronic stress can dysregulate the HPA axis, leading to prolonged activation. Once a trusted ally, cortisol can now become a formidable foe, wreaking havoc on your body and mind.

The hippocampus also bears the brunt of this assault. Chronically elevated cortisol can cause the hippocampus to shrink. As a result, the structure and function of the hippocampus are impaired.

Effects of Persistent Stress on the Peripheral Nervous System

Ongoing stress affects your PNS in the following ways:

Overactivation of the SNS and Underactivation of the PSNS

In times of stress, your body's SNS springs into action, triggering what's commonly known as the "fight or flight" response. This response is designed to prepare your body to either fight or run away from the stressor. When activated, the SNS:

·       Speeds up your heart rate.
·       Raises blood pressure.
·       Causes your pupils to dilate.
·       Induces stress hormone (adrenaline and cortisol) release.

On the contrary, PSNS helps bring your body back to its relaxed state after the stressor fades. The PSNS counteracts the effects of the SNS by:

·       Slowing down your heart rate.
·       Lowering blood pressure.
·       Returning your body to its normal resting state.

But unrelenting stress causes your SNS to go into overdrive. It's like a car engine revving at high speed for prolonged periods, eventually leading to wear and tear. A perpetually overactive SNS drives problems like chronic inflammation, cardiovascular diseases, and weakened immune response.

At the same time, your PSNS becomes hypoactive, contributing to digestive issues, weakened immunity, and difficulty recovering from stress. 

Upsetting the Enteric Nervous System (ENS)

Another crucial player in this stress response is the enteric nervous system (ENS), often called the "second brain." The ENS regulates your digestive processes and cross-talks with your primary brain.

But constant stress can derail this communication, promoting gut-brain axis dysfunction and mental health issues, such as anxiety and depression.

Directly Impacting your Peripheral Nerves: Inflammation and Nerve Damage

Stress can also impact your peripheral nerves directly. It precipitates the release of signaling molecules that promote inflammation in your body. This chronic inflammation can damage nerves, leading to nerve pain, numbness, tingling, and other sensory disturbances.

Inducing Muscle Tension and Pains

During acute stress, your muscles may tense up suddenly and then relax once the stressor fades. However, in the phase of chronic stress, this muscle stiffness can last for prolonged periods, causing pain and limited mobility. This prolonged muscle tension can give rise to headaches, neck/shoulder pain, and muscle/bone problems.

Key Takeaways

Chronic stress can disrupt the normal function of your nervous system, both centrally and peripherally. From the brain to the peripheral nerves, it triggers a cascade of responses that can wreak havoc on your well-being. It can lead to mental health disorders, impaired cognitive function, disturbed sleep patterns, weakened immune response, and muscle/bone problems.

Addressing stress with coping strategies, self-care, and seeking help when needed for overall health and resilience is crucial.

Big Calm focuses exclusively on nervous system well-being. Learn more about how to restore your nervous system to health by visiting the offerings page.

References
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