BDNF and stroke disorder: The present meta-analysis showed decreased serum BDNF level in patients with PSD, compared to stroke patients without PSD with a random-effects model (mean value of BDNF level [PSD vs. stroke patients without PSD]: 14.106 vs. 17.995 ng/ml; SMD = -1.578; 95% CI: -2.820, -0.337; <i>I</i> <sup>2</sup> = 97.8%, <i>p</i>-value for Q test < 0.001).<h4>Conclusion</h4>Brain-derived neurotrophic factor may work as a potential biomarker to predict the risk of PSD among stroke survivors.