Stress And Anxiety: The Similarities And Key Differences

Stress and anxiety are interrelated and can occur separately or together. In many cases, anxiety is your worries or your interpretation of stress. Stress is your body’s actual response to real or perceived threats.

Both stress and anxiety in the short-term can be beneficial to humans, but can also be harmful in the long-term for almost the same reasons. They elicit very clear nervous system responses which, in the case of real and imminent danger, help humans protect themselves or get them out of harm’s way — the classic fight or flight response.

However, when this state is consistently invoked and on a long-term basis, it can be very harmful to us. 

In this article, we aim to outline the relationship between stress and anxiety, how it can be detrimental, and ways to combat it. 

Have you considered clinical trials for Anxiety?

We make it easy for you to participate in a clinical trial for Anxiety, and get access to the latest treatments not yet widely available - and be a part of finding a cure.

The stress-anxiety relationship

Stress is defined as being a generalized response of the body to demand. Stress can be thought of as any type of change that causes physical, emotional, or psychological strain. When the demands are perceived to be beyond the ability of the individual to cope, this creates feelings of fear and anxiety. 

Fear and anxiety themselves are similar, but not the same. Fear is defined as being the alarm response to when a real and imminent danger is perceived. Whereas anxiety is future-oriented and occurs when upcoming negative events are anticipated or contemplated. 

From the above general definitions, we see that if you feel as if a situation is out of your control, it will demand more from you than you have available to give. In that case, you begin to feel fear at the danger of having no reserves remaining, not being able to escape, or perhaps even failing. 

When you contemplate the effects of these feelings and what that means for your future self, you feel anxiety. 

What’s happening on a biological level when someone is stressed?

A key area of your brain that is involved in your stress response is the hypothalamus (an area in the base of your brain). When you encounter a potential threat or stressor, your brain compares it to any previous exposures that are similar. This is how you learn to avoid situations that can cause you harm. 

If your brain decides it recognizes stress, it will initiate a stress response. When a stress response is triggered, it sends signals to two other structures in your brain called the pituitary gland, and the adrenal medulla. This system then releases hormones (like adrenaline) that prepare your body to fight or flight (or to stay where you are and feel extremely stressed). 

This system that regulates your immediate stress response to immediate threats is known as the Sympathomedullary Pathway (SAM). 

When you’re exposed to long-term stress, such as difficult family life, trauma, abuse, or other challenges, your stress response is regulated by a different system known as the hypothalamic–pituitary–adrenal (HPA) axis. 

While SAM is kind of like lighting a match, the HPA axis is more of a slow-burning fire. HPA activation is associated with long-term health problems because the stress response in your body remains elevated.  

What are the effects of these stress hormones?

The released stress hormones, such as catecholamines, result in cardiac changes which are felt as an increased heart rate. Specifically, cardiac output (the amount of blood being pumped through the heart) is increased, which helps to increase blood pressure. 

Blood is also shunted away from non-urgent locations like the skin and gut so that it can be redirected to the skeletal muscle and heart, which are required if the person needs to fight or run as quickly as possible from imminent danger (fight or flight). 

Of course, all this extreme pressure (increased work of the heart and skeletal muscle) requires energy to keep it going for the duration of the stressor. To provide this energy, the glucocorticoids, and epinephrine act together to increase the circulating blood glucose. 

Glucocorticoids¹ also help to inhibit the body’s own immune response, which would normally be activated in response to stress. Glucocorticoids are more likely to be released as a result of a long-term stress response (aka HPA axis activation) rather than when you encounter immediate stressors. 

When your body releases glucocorticoids, it also suppresses your immune system to prevent your immune cells from initiating an immune response. While this is helpful when you’re going through a stressful event, too much stress can result in an increased risk of getting sick. 

The biology of fear and anxiety

The differences and similarities of the biological basis of fear and anxiety lie in understanding the differences in the words and what they refer to. 

Fear refers to feelings when a source of harm is certain and imminent. Anxiety refers to feelings when the source of harm is uncertain, perceived, or is still at a distance (either timewise or spatially). 

It is thought that when fear is experienced, the fear circuit² kicks into play, which is controlled by the amygdala in the brain. The amygdala is an area of the brain that is activated in response to fear. It then communicates with another area known as the central nucleus, which triggers defensive behaviors such as freezing or fleeing. 

In the case of anxiety, it is thought that it originates in an area known as the bed nucleus of the stria terminalis (BNST)². This area gets triggered when a threat is uncertain in nature and results in defensive actions such as escape or avoidance of the source of anxiety. 

Studies² have backed up these theories using people who have amygdala (fear hub) damage and are thus unable to show bodily responses to imminent danger. Likewise, those who suffer from anxiety disorders show a heightened response from the amygdala in response to stressors.

The behavioral differences in response to fear and anxiety

Generally, if the imminent danger or threat is surmountable or escapable, then it results in autonomic nervous system activation³ to enable you to fight or escape the danger.

However, when the threat is inescapable, it results in autonomic nervous system inhibition, which is characterized by a freeze response that causes you to become immobilized. The instinct to fight, escape or freeze are all, in fact, adaptive behaviors designed to keep you safe in the face of danger. 

Some people believe that when the danger is certain, fear is the predominant response, which most likely results in the instinct to fight or flee, as mentioned above. 

When the danger is uncertain, then anxiety is the predominant response, with immobilization³ being favored as a reaction. This remains true until such time as the threat either diminishes or comes closer and becomes certain. 

Despite these generalizations of human behavior in stressful or dangerous situations, in the real world, everyone is different in how they respond to stress, whether it be consciously or subconsciously, and this is largely due to the individual’s adaptive responses to stress.  

The symptoms of stress

Stress may occur in your life without you even realizing it because of the adaptive nature of your stress responses. Here are some symptoms of stress to look out for:

  • Irritability and impatience

  • Feeling overwhelmed

  • Anxiousness 

  • Racing thoughts

  • Lack of enjoyment in things

  • Lack of interest in usual interests or hobbies 

  • A sense of impending doom

  • Loneliness

  • Insomnia

  • Changes in appetite

  • Increased use of substances

  • Gastrointestinal changes

  • Shortness of breath

  • Fatigue

  • Aches and pains

  • Skin problems

  • Changes in sex drive

  • Chest pain

  • Pounding heart

  • High blood pressure

  • Teeth grinding 

The symptoms of anxiety

Here are some symptoms of anxiety that may be apparent to you or those around you:

  • Irritability and frustration

  • A sense of impending doom

  • Cardiovascular changes such as raised blood pressure or increased heart rate

  • Changes in breathing patterns (breathing rapidly)

  • Fatigue

  • Weakness

  • Insomnia

  • Gastrointestinal changes

  • Concentration difficulties

  • Shakiness 

What are the similarities?

Many similarities are apparent in the symptoms of stress and anxiety. 

Stress may result in changed behaviors (substance abuse, withdrawal from stimuli, snapping at family members). Anxiety may be more chronic and result in bodily changes such as a persistent increase in blood pressure, cognitive changes such as difficulty concentrating, and the development of diseases that are evident in anxiety disorders. 

How stress and anxiety are treated

There are many approaches to treating stress and anxiety. 

Cognitive behavioural therapy 

The initial approach to treat stress and anxiety is cognitive-behavioral therapy (CBT). 

This is where you’re guided through an analysis of what is going on and the therapist educates you on what is causing the stress and anxiety, your responses to it, and how to change your behavior. It’s built on the premise of facing your fears so that you may correct maladaptive behavior patterns and develop new and less pathological adaptive responses to the stressors you’re facing. 

This can also include ways to manage your stress responses through the removal of stress, putting healthy boundaries in place, practicing breathing exercises, or meditation

Vitamins and nutrition

Vitamins and nutrition (to ensure healthy levels of circulating nutrients) are fundamental to the management of stress and its effects on the body. 

As an example, vitamin C is normally depleted by stress, which places the body in a vulnerable position when warding off infection and disease. 

Vitamin C is also thought to support the adrenal glands, which we have shown are implicated in the fear and anxiety responses.

B-vitamins are important in maintaining the nervous system⁴. They are good at regulating blood glucose, which keeps the mood and energy levels stable. Deficiencies in B-vitamins can cause stress-related responses such as irritability, low mood, and frustration. 


If the anxiety is severe, medication can be used, alone or in conjunction with psychotherapy. The medication is usually in the form of antidepressants, which can reduce the symptoms of anxiety and make it easier to cope. 

Studies⁵ have shown that the use of selective serotonin reuptake inhibitors (SSRIs) alleviated many anxiety-related conditions, including generalized anxiety disorder (GAD), panic disorder (PD), social anxiety disorder, and post-traumatic stress disorder (PTSD). 

The lowdown

Stress and anxiety are two inextricably linked conditions that can result in very similar symptoms in the individual. Stress is the response to danger or a stressor, and generally precedes fear and anxiety, which are the responses to certain and uncertain dangers, respectively. 

Because of the link between stress, fear, and anxiety, similar treatments are beneficial across all conditions.

Have you considered clinical trials for Anxiety?

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