Patients in this study were evaluated at a median time of 5.6 months (170 days) post-injury, which is consistent with the diagnosis of chronic PTH (defined as a PTH continuing after 3 months).1 As hypothesized, we found that, in our cohort of patients, the factor most significantly associated with headache disability was the presence of comorbid PTSD symptoms. This evidence concerns the gene PTH and post-traumatic stress disorder.