Table 3. Correlations between mtDNA copy number and other variables in MDD patients.

Variables	rs	P-value
Age	−0.080	0.251
Age of onset	−0.098	0.157
Episodes	0.095	0.168
Education	−0.042	0.548
HDRS score	−0.145	0.035*
GAF score	0.004	0.956

r_s: Spearman's rank correlation coefficient; HDRS: Hamilton Depression Rating Scale; GAF: Global Assessment of Function Scale.

p calculated by the Spearman’s rank correlation test.

^* p = 0.035<0.05, but the correlation coefficient (r_s) = −0.145>−0.2, so the correlation between mtDNA copy number and HDRS score are still not significant.