Friends say the man fatally shot by police in Charlotte, North Carolina last month was on medication for a traumatic brain injury that made him sluggish and forget what he was saying mid-conversation.

Neurologists say they aren't surprised that someone with an injury like Keith Lamont Scott's would be slow to react and have difficulty following instructions, particularly in a high-stress situation like a police encounter.

Police say they shot Scott Sept. 20 after he refused to drop a gun. In cellphone video, Scott's wife is heard shouting to police that her husband "doesn't have a gun, he has a TBI."

Scott was injured in a November 2015 motorcycle crash. Dr. David Brody of Washington University says someone with a severe TBI often makes poor choices or impulsive decisions under stress.