Instead of classifying concussions by grade (Grade 1 =
mild, Grade 2 = moderate, Grade 3 = severe), the Prague statement classified concussion as either simple or complex, depending on the type, duration and number of
symptoms and how long they took to resolve:
NMS actually usually appear earlier in PD than the motor
symptoms do, but at that point they're so
mild — and also so common in aging people — that they usually aren't recognized as the first signs of the pathology to come, but are
instead put down to so - called «normal aging».