Mark thanks! I 've suffered a concussion yes. Not exactly what you wrote. I 'm concerned that altered membrane cholesterol prevents recovery. Or better - I am convinced, not concerned... But I 'd like to know what I asked. It's true that sometimes serum cholesterol levels might look fine, but (CSF) membrane cholesterol might be low. I know this has been proposed as a cause of depression (and a side-effect of statins). Recently I found evidence how low membrane cholesterol prevents glutamate reuptake by cells. I 'd love to know the levels though (of people with PCS). Actually the pre-injury would make more sense.