Preventing PTSD, depression and associated health problems in student paramedics: protocol for PREVENT-PTSD, a randomised controlled trial of supported online cognitive training fo... by Wild, J, El-Salahi, S, Tyson, G, Lorenz, H, Pariante, C, Danese, A, Tsiachristas, A, Middleton, B, Blaber, A, Ehlers, A