According to the APA (American Psychiatric Association), mental illnesses are health conditions involving changes in emotion, thinking or behavior (or a combination of these). Mental illnesses are associated with distress and/or problems functioning in social, work, or family activities.
That definition follows the medical model, and since the mind is not something that can be tested in your blood or under a microscope, doctors have the tendency to assign diagnoses to behaviors or emotional expressions that in many circumstances are even healthy. Doctors medicate grieve for example, which is a process absolutely necessary after loss, and medicating it represses a natural phenomenon. I dislike that approach.
I prefer to call them either disorders or diseases. “Disease” is something that needs to be cured. Illness is something that needs to be managed. Emotional problems need to be healed, as in corrected; the idea of managing emotional problems and learning to cope with them sound to me like a life sentence, as in something that can’t be overcome.
A disorder is an even better term since its definition is that the systematic functioning got disrupted and needs to be brought back to where it was before the disruption. So, emotional disturbances should be called disorders, or dysregulations, or to make it simpler, mental challenges.
The word “trauma” comes from the Greek and means “wound.” That’s what trauma really is! As Katie John mentioned in her comment on this response, trauma is an injury. The nervous system gets injured because of the way the defense mechanisms operate when they have to overwork. The system gets stressed to the point of hurting its regular flow, and then it stays altered and malfunctioning from then on. That’s what trauma really means.
What many clinicians should evaluate is whether a person’s level of distress is creating disfunction. And recovering functionality should be the main goal.
Neuroscience has also been really helpful in understanding mental issues, since it has shown that emotions are “energy” that either flows through our body motivating us for action, or get stuck somewhere in our body, disrupting the flow and therefore giving us misinformation and pain. It has also shown that the way the brain reacts is by changing the amount of energy used to communicate between the different functions: they either get overactive or underactive; they go too fast or too slow. That’s very helpful in terms of healing. Regulating the brain waves is a clear way to correct the functioning and therefore recovering stability, impulse control, perception, and therefore, behavior.
So, is C-PTSD a serious mental illness? Let’s call it a challenging mental dysregulation that “disorders” the way we should react, think, perceive and behave. And yes, it could be serious, depending on how long the exposure to the toxic stress was, and at what age.
Yes, traumatic events can cause mental illness besides PTSD. Trauma refers to a mental illness and not to an event. It’s common to use the word indistinctly but to make it more clear, clinical professionals make a distinction between traumatic events, traumatization, and trauma as a disorder, which many people call PTSD.
People that experience traumatic events not necessarily develop trauma (or PTSD).
Trauma as a disorder is something that doesn’t happen overnight. Even if you suffer from traumatization during and after a traumatic event, and could present PTSD symptoms right after the traumatic event, the brain has a natural tendency for healing and the system will try to use it to avoid you from getting sick and maintaining a permanent dysregulation that will cause you to suffer and your system to struggle.
If a person is resilient, PTSD symptoms start dissipating a few weeks to 6 months after a specific event even without intervention. If instead of a specific event, the traumatization occurred during a prolonged period of time, complex trauma (or C-PTSD) will most probably develop. The severity of the disorder and how permanent it becomes will depend on your resilience but also on the level of risk, the time you endured it, and the depth of the wound. Complex trauma doesn’t disappear by itself. It needs professional help to heal from it.
Other mental illnesses that could develop due to traumatization are most personality disorders, depression, anxiety, paranoia, addictions, etc. These are sometimes considered symptoms of the trauma, and sometimes are considered comorbidities —the simultaneous presence of two chronic diseases or conditions in a patient.
PTSD & C-PTSD are only two of the disorders in the trauma spectrum. The recognition of psychological trauma is a recent development. After the Vietnam War, when the evidence for the mental consequences on veterans was overwhelming, that PTSD was accepted as a mental disfunction, was included in the Diagnostic and Statistical Manual of Mental Disorders (DSM) as a disorder, and insurance companies started paying for its treatment. It’s basically the only trauma disorder that has been recognized officially by the psychiatric world. But every day we learn more about all the consequences and illnesses that derive from traumatization.