In patients aged 18–64, the most significant difference between PCS and TBI was noted in the prevalence of headache (78.4% vs. 53.3%) followed by dizziness and giddiness (60.1% vs. 35.7%) and BDNF (Val66Met; 59.8% vs. 37.6%; Figure 2Bi). The gene discussed is BDNF; the disease is Headache.