It is a standard misconception that symptoms of PTSD appear instantly after injury. Actually, this fallacy couldn't be farther from the truth.
Research to date tends to generally say that symptoms will appear within 3 months of the injury. Don't confound that as, "I 'll have all symptoms to meet PTSD within 3 months." That isn't what I am saying, nor what present research discusses. The National Institute of Mental Health quotes this precise data.
There is no single authoritative solution to when symptoms appear or how many will show up and when. The most common opinion in the field is that someone may have one or more symptoms within 3 months. Think about it like this -- you may lose sleep immediately, have bad dreams. That's one symptom, and it would be natural to experience nightmares and insomnia after experiencing injury. That subsides, and you may find that you isolate yourself a month later -- another symptom. You may have a really hard week on emotional trauma the job then explode at someone. It happened this some months after your traumatic event, although you've never done that before after a rough week. This is another symptom.
All the above are single, detached symptoms of PTSD. You aren't experiencing those symptoms simultaneously. You experience them as isolated, even seemingly dissonant, events. You may experience them simultaneously, yet they're still a mere three symptoms of many needed for a PTSD diagnosis. This is what most research points to in relation to having symptoms within the first 3 months after your traumatic exposure.
Without experiencing the symptoms required to fulfill diagnosis having PTSD, isn't all that different --on a much smaller scale -- from how we experience viral infections. You then experience the symptoms the following weekend, incubate it for 5 days with no symptoms, and may get a virus from your child on a Sunday. You were infectious and carried the virus all week, but how could you possibly understand? Perhaps you felt a bit of a sore throat as the week wore on or had some sniffles, but it's the correct time of year to have seasonal allergies. It doesn't mean you did not have a virus, merely that you did not meet with the telltale signals you'd need to seek help and subsequently get treatment.
On a bigger scale about sufferers of dementia? Many individuals with dementia experience a few symptoms for months or even years before realizing there's a real issue going on. They become disoriented every now and again or lose their balance. If they are stumbling here and there or sometimes being forgetful doesn't set off any alarm bells, the same way that being anxious, of a particular age or on guard following injury is an absolutely non-pathological reaction to lately experiencing trauma. It often takes more time, and definitely requires more symptoms to be ticked off, before detecting you have a chronic issue, even if you do in fact already have the disease.
To further demonstrate the variability for when symptoms start, MyPTSD has polled this exact question for 9 years. Our member poll results, those people who have replied, demonstrate that 31% experience symptoms in the first three months, with 49% taking.
Our results show a substantially broader result set taken at the time of writing this post over 9 years. If a single statement was made by MyPTSD, as the NIMH and other sources state that is important, then our view would be that the majority of folks take more than 12 months to experience symptoms.
This view aligns with resilience data (also mentioned by NIMH) that most people exposed to trauma do not develop PTSD, let alone symptoms that would be viewed as a mental health state. PTSD from a single occasion is much scarcer than PTSD from compounded stabbing events throughout life.
In a nutshell, the myth that PTSD appears directly following a traumatic event has little basis in reality. Without growing full blown PTSD sufferers can go years, even decades. Build a community around themselves of encouraging, compassionate people that are both honest and understanding and the best thing injury survivors can do is to get help as fast as possible. This foundation of support will function as a resiliency tool, and it can be invaluable in helping those who experience trauma return to a sense of normalcy. The honesty of others can serve as a check against irrational and uncharacteristic behaviour -- an extra set of eyes to track the survivor for signs of a growing problem. Furthermore, seeking a professional's help following trauma has clear and manifold advantages, whether to help mitigate developing symptoms with medications or merely serve as a guide to return to a secure, healthy lifestyle post-trauma.