BDNF and post-traumatic stress disorder: This was confirmed in PTSD smokers, as CT genotype carriers had nominally lower ROCF immediate recall scores (H = 7.275; df = 2; p = 0.026) than carriers of the other BDNF rs56164415 genotypes, and this relationship was confirmed with significantly decreased ROCF immediate recall scores in T compared to CC genotype carriers (U = 86.0; p = 0.024), while there was a trend in T vs. C allele carriers (U = 267.0; p = 0.063).