Nearly every time I drove, I thought I saw the woman I’d hit. She’d flash ahead of me, a face in the headlights. Or, if I didn’t see her, I’d imagine her suddenly stepping onto the road. On the dashboard, I noticed cuts in the vinyl from when her back had burst through my windshield. I avoided driving on the highway to work. I took Clairmont Road instead, the slower and, I hoped, safer route. Its four lanes run through leafy neighborhoods, winding past schools, grocery stores, drab strip malls. Still, driving left me feeling under siege, half-crazy about the dangers of this thing I did every day. Much later, I came across a study in which researchers found that almost 40 percent of people involved in car accidents developed PTSD. Symptoms: frequent, intrusive thoughts or dreams about the accident; fear of driving; feeling isolated even from close loved ones; insomnia—and intense guilt, whether the person was at fault or not. J. Gayle Beck, a psychology professor at the University of Memphis, is one of a handful of researchers who studies PTSD linked to car wrecks. Being in a serious accident, she told me, “violates our beliefs about how life should be and who we are.” We think we’re in control of what happens on the road. If we’re in control, then we must be responsible.