Is Overdoing-It the cause of Post-Concussion Syndrome? I think so because overdoing-it triggers an over-active neuro-inflammatory response which leads to prolonged inflammation and related symptoms.

People should not have to suffer with concussion symptoms for months after a head injury. Most concussions heal within 7-10 days. When people have symptoms that last longer than that, it's probably because they didn't rest enough in the beginning.

Let me give an example of what I mean by overdoing-it. Many years ago, I had a bout of PCS. I fell out of a chair and hit my head. The next morning, I felt ok, and it was a holiday weekend, so we went to the Wild Animal Park. All the people and noise and activity really made my head hurt. I tried to stick it out for a few hours but finally said we had to leave. Then my symptoms persisted for 6 months.

If I had stayed home and rested, my concussion would have healed within a week, and I would have been fine. But because I pushed through the pain, I suffered for many months.

Let me clarify, some cognitive activity is ok. It's the high-level intense cognitive activity that is detrimental and should be avoided. But that includes activities like computer work, academic work, school homework, or going to theme parks, activities we want to do every day. So, to put it in other words, don't overdo-it. Find a balance between resting and activity such that you don't exacerbate symptoms.

There are two injuries that occur during a concussion. First there is the impact force and then there is the inflammation that the brain produces in response to the impact. Inflammation has a beneficial role in the beginning, but prolonged inflammation is bad. It has a damaging effect and can cause more symptoms than the initial impact.

If we examine head injuries that result in PCS, in most cases, the impact force is not enough to cause long-term symptoms. Anxiety alone is not enough to cause long-term symptoms. So that means inflammation is the culprit. (There are other factors that contribute, like structural damage, vascular disruptions, signaling disruptions, but those are out of our control, whereas overdoing-it is something we can avoid.)

There has been talk about how anxiety can cause concussion-like symptoms without a forceful impact, and how people with a history of anxiety are more prone to PCS. That's because anxiety is linked to brain inflammation. If anxiety can do that, then overdoing-it can also cause brain inflammation.

The brain's inflammation response system is on high alert after a blow to the head and stressors can trigger it to pump out inflammatory compounds to look for and repair damaged cells even if there is no damage. Intense cognitive activity can trigger this over-active neuro-inflammatory response. Then it takes a long time for the brain to clean up the inflammation and learn to stop over-reacting, hence Post-Concussion Syndrome.

This research study suggests that after a concussion, adolescents with the highest level of mental activities — such as reading, doing homework and playing video games — take the longest to recover.
Cognitive Rest After a Concussion Speeds Recovery | Psychology Today

If we have a better understanding of what causes Post-Concussion Syndrome, then we can prevent it and provide better treatment.