, in certain circumstances , a veteran who has been diagnosed with PTSD by a VA or VA - contracted psychiatrist or psychologist based on a claimed stressor that is related to the veteran ' s fear of hostile military or terrorist activity may establish the occurrence of the claimed in - service stressor with lay testimony alone . In this case , however , the Veteran has not argued to the Board that her stressors are based on fear of hostile military or terrorist activity , nor is there any evidence that the Veteran served in the vicinity or at the time of any military or terrorist activity . This provision therefore does not apply in the current case . The Board has considered all of the