That sounds similar to when an impact results in diffuse axonal injury. Axons throughout the brain get weakened.

If he will follow the regimen, I would encourage you to get him on the Vitamins regimen in the Vitamin sticky at the top. The weak brain needs far more nutrition to tolerate daily stress and activities. Also, his quality of sleep will make a big difference. After a bad night's sleep, he will have more struggles.

He likely struggles to filter out background sounds and voices. This can make it difficult to follow a conversation. Memory and retrieving ideas often has to do with focus. He may need an opportunity to 'stop to think.' The stress of trying to force thought is often counter-productive.

Family can help him by giving him time and quiet to think and speak. I bet he struggles miserably at something like a Thanksgiving dinner with lots of people, maybe even to the point of outbursts.

People need to realize that he is as frustrated by his situation as they are. He likely does not fully understand why he struggles so and ends up 'smashing into walls' so to speak. He may be struggling with depression. It is a common part of his condition.

Please let me know if you think I am on track.

My best to you both.