Researchers investigating PACAP/ADCYAP1 and PACR1/ADCYAP1R1 in relation to PTSD in a predominantly African− American sample with a mixture of trauma types found that, in women more than men, increased PACAP blood levels were associated with increased PTSD symptom severity and an increased acoustic startle reflex response [64, 89]. Here, ADCYAP1 is linked to post-traumatic stress disorder.