Back to Blog
FND patients, FND causes

Understanding the cause of your Functional Neurological Disorder (FND) and Functional Illnesses

dr. velazquez fnd causes fnd education fnd mechanisms of production functional disorders functional illnesses functional neurological disorders (fnd) Jan 29, 2023

Hi there! Welcome to our learning space 😊

Today we will review in more detail the causes of Functional Neurological Disorder (FND) that have been described in the literature, and from that foundation we will try to uncover the causes of FND that apply to you. Becoming aware of such, is the first step towards self-healing, and positive self-transformation, without having to depend on an often faulty, and inadequate healthcare system, and its providers, but on the other hand, acquiring the knowledge necessary to teach them, advocate for yourself, and help prevent FND in those around you.

It is commonly heard that FND is often the result of “stress” and “trauma”, so let us start by reviewing those concepts.

Stress: state of mental, emotional, and/or physical tension, caused by a multitude of factors and events

Stress is a physiological response that takes place to help us overcome a situation, it appears as a response to a challenge or a demanding event. Stress, when it takes place, permeates the mind with its cognitive processes (reasoning, planning, perception, etc.). It involves equally the emotions (fear, sadness, etc.) and the physical body (increased heart rate, trembling, etc.).

Let us think of that moment when you had a physical illness. Your immune system, various hormones, and neurotransmitters needed to shift to adapt, to combat, this period of extra energetic and material demand and tension.

Let us now consider a different example: a snake in your walking path. Your mind will perceive the threat, your emotions will likely respond with fear, apprehension, or others and your body, will likely jump involuntarily, heart racing and sweating may appear.  So, any challenging situation, in any normal, healthy human being, triggers a reaction in the physical body, the emotions, and the cognitive mind.

Trauma: occurs when the trigger, the challenge, the demand is much more profound in duration or intensity, more sustained or impactful, overwhelming the organism, emotionally, mentally, and physically

Utilizing the same example of the snake above, consider that, as you are trying to escape, you encounter other snakes in your path, you have to run faster, find an exit rapidly and desperately, your mind is assessing all possibilities, your emotions overwhelm you with signals so you do not give up and continue trying to escape, your body feels extremely energized, muscles contracted, blood flowing rapidly and heart pumping out of your chest! Depending on the duration of the event and the final outcome, two things will likely happen: #1) it will take much longer for your organism to calm down and recover its natural estate of rest, relaxation and recovery, and #2) very likely the situation will leave an imprint in your being, a subconscious and/or conscious lesson and learning experience, that have taught you not to walk on that path, because it is dangerous, it can affect, and it has affected your overall wellbeing, your options of health and survival. Perhaps the signal and the effect in your organism were so intense that you feel inclined to avoid hiking all together. The situation left a scar, an imprint in your being, and this will likely shape your future interactions with the world.

In the case of the physical illness, perhaps the lesson will be not to get to close to those who are sneezing and coughing, or not to walk barefoot on the snow. These are normal responses, learned thought processes and behaviors, that our organism working together, mind-body-emotions, triggered by environmental events, have designed to keep us healthy, happy, and alive.

Our bodies are amazing! Mother nature is wise!

Then, how can these processes turn into an illness, into Functional Neurological Disorders (FND), and even perhaps other functional illnesses (FI) like the ones mentioned in this article?

Life's adversities can trigger functional neurological dysfunctions, symptoms, and illnesses through various mechanisms, for example, through the learning that took place. This have been described in the literature as “Cognitive and Learning Theories”, or through subconscious associations and coupling, that later manifest involuntarily.

In summary, before moving on to the next section: Stressors, challenges, environmental adverse events can unleash a series of changes within our organism that can lead to FND and FI in certain individuals. But please note, the stress theories are much more complex than that, because they include the study of the effects of stressors in numerous glands, endocrine, autoimmune, neurological and biological systems.

As we all go through life’s adversities, the events trigger certain sensations in the physical body or physical responses. For example, heart racing, tightness in the stomach, trembling, muscle tension, and many other sensations that usually appear in association with emotions. Those compounds of sensation – emotion – situation get stored in our memory, subconsciously, as part of learning mechanisms, to keep us safe in the future. It is our life’s record.

Since there are millions of challenges and demands, mild and severe, that we experience from the moment we are in our mothers’ wombs onwards, that are stored mainly in the subconscious mind, we eventually forget, in the conscious mind, about the original trigger, we do not recall it, and this is normal. We must save memory storage!

The problematic part, and what contributes to the production of FND, is that, later in life, we may go through a similarly challenging situations, and subconsciously our mind may activate or retrieve the previously stored compound sensation – emotion – situation, which can be surprising, scary, overwhelming, and even shameful for some. Imagine that the event with the snakes took place when you were 5-year-old, and now at the age of 35, you are hiking with your friends. Suddenly, there is a loud sound coming from the grass, and inadvertently you find yourself shaking, trembling, sweating, heart pounding, with a feeling of apprehension. Your friends on the other hand are calm, curious, and even laughing. They look at you strangely and you all wonder “what is happening with you??” Of course, as you do not consciously remember what you went through at the age of 5 y.o., you wonder if your body has some kind of a disease.

From this moment onwards you start monitoring your body. You notice frequent fluctuations in your heart rate, subtle changes in temperature in your extremities, moments of stillness alternating with mild inner tremor, so you decide to go to the doctor, and they think the worst! The doctor tells your symptoms may be due to Parkinson, or Paroxysmal Orthostatic Tachycardia Syndrome (POTS), and you become worried, more attentive. Now you are navigating a whole new challenging situation! The stress responses may become chronic given the new worries, challenges, blood tests, scans, doctors’ appointments. Cognitive and learning mechanisms derived from what others tell you and what your own mind infers, kick in. Your mind and body start to malfunction, misfire, become disconnected, spiraling out of control. The mind wonders “what is wrong with this body?”, “why is this happening to me?”, without being told by anyone, not being taught, not realizing that simply an old pattern got activated, and it needs attention to repair and reintegrate itself, into your new, wiser, more experienced self.

There might be self-suggestions that take place too. Your emotions start becoming predominantly heavy and negative, and old defense mechanisms may also become activated to protect you from such storm. These are some of the processes involved in the origin and maintenance of FND.

The examples above summarize the most comprehensive theories that have been proposed in the literature, to explain the production and maintenance of FND, which in truth are intertwined. Below are outlined, the theories that have been described in the literature:

  1.  Stress (physical/psychological) model
  2.  Childhood trauma
  3.  Neurobiological theories
  4.  Cognitive and learning theories
  5.  Hypnosis
  6.  Psychological model
  7.  The limbic system (the brain emotional center)
  8.  Defense mechanisms


During subsequent articles we will review some of these theories in more depth. 

Let us proceed now with some exercises to make sure we are understanding these important concept: 

  1. Consider: have you been through any stressors, difficulties, challenges, life adversities since you were in your mother’s womb? Name some of them. How do you think they have shaped the way you interact and interpret the world in the present moment?
  2. Get curious: Read the above list of proposed theories that explain the production and maintenance of FND. What do those names tell you? What can you infer thinking of them? If you have FND or FI, do you think what has happened to you could be related to any of those theories?
  3. How does it make you feel to see that there is so much understanding nowadays compared to decades ago, in the field of FND and FI?
  4. Are you excited to continue learning about the causes and the theories that explain how FND is produced? What other emotions appear in your being when you consider the possibility of becoming your own healer, and/or helping those who have been touched by FND?
  5. What do you think of the concepts of stress and trauma that I provided in this article? Do you have any other definitions or considerations that you would like to share?


Remember, the meaningful task of understanding, healing, and preventing FND and FI is in your hands too! Thank you for ACTING TODAY, it at least, by learning and sharing knowledge 😊

At your service,

Yadira Velazquez, MD

Neurologist and Clinical Neurophysiologist

FND and FI Healing ally.


Join our Mailing list!

New inspiration and information delivered to your inbox. 

We will never sell your information, for any reason.