NTRK2 and Anxiety: Besides, TrkB-FL mRNA levels were positively correlated with anxiety (r = 0.470, p = 0.037; the difference was no longer significant after Bonferroni correction) as measured by the SAS after exercise intervention for METH addicts, while TrkA mRNA, TrkB-T1 mRNA, TrkC mRNA, and P75NTR mRNA levels were not associated with anxiety (r = −0.192, p = 0.416; r = −0.423, p = 0.063; r = −0.149, p = 0.530; r = 0.018, p = 0.940; see Figure 3).