Table 2.

Spearman’s/Pearson’s correlations between demographic, psychopathological, neuropsychological characteristics, and serum BDNF and IGF-1 levels in MDD patients and healthy controls.

Variables	BDNF (pg/ml)	p	IGF-1 (ng/ml)	p
Demographic characteristics
Age, years	0.02	0.9	-0.17	0.16
Gender	0.15	0.20	0.10	0.44
Depression status	-0.57**	<0.0001	0.50**	<0.0001
Persistent stress	0.06	0.59	0.01	0.93
Precipitating factors	-0.33**	0.004	0.20	0.11
Recurrence of DE	-0.03	0.79	0.16	0.19
Number of DE	-0.04	0.75	0.43**	0.001
Duration of DE, weeks	-0.02	0.85	0.37**	0.002
MDD in relatives	-0.12	0.32	0.05	0.68
Clinical assessments
CGI-S score	-0.44**	<0.0001	0.45**	<0.0001
PDQ-5 score	-0.19	0.16	0.43**	<0.0001
MADRS total score	-0.43**	<0.0001	0.46**	<0.0001
RAVLT immediate recall total score	0.33**	0.007	-0.42**	0.001
RAVLT proactive interference score	0.19	0.11	-0.40**	0.001
RAVLT retroactive interference score	0.17	0.16	-0.42**	0.001
RAVLT delayed recall score	0.23	0.06	-0.37**	0.003
RAVLT delayed recognition score	0.18	0.14	-0.19	0.15
TMT-B (s)	-0.27*	0.03	0.55**	<0.0001
DSST score	0.24*	0.048	-0.45**	<0.0001
SDS Work score	-0.37**	0.003	0.40**	0.001
SDS Social score	-0.46**	<0.0001	0.39**	0.002
SDS Family score	-0.38**	0.002	0.40**	0.001
SDS Total score	-0.43**	<0.0001	0.43**	<0.0001
SDS absenteism, days	-0.12	0.35	0.23	0.07
SDS presenteism, days	-0.36**	0.003	0.31*	0.01
Serum proteins` levels
Serum BDNF level	1	–	-0.17	0.18
Serum IGF-1 level	-0.17	0.18	1	–

BDNF, brain-derived neurotrophic factor; CGI-S, clinical global impression—severity of illness; DE, depressive episode; DSST, digit symbol substitution test; HC, healthy controls; IGF-1, insulin-like growth factor; MADRS, Montgomery-Asberg depression rating scale; MDD, patients with major depressive disorder; PDQ-5, perceived deficits questionnaire—5 items; RAVLT, Rey auditory verbal learning test; SDS, Sheehan disability scale; TMT-B, trail making test part B.

*p < 0.05 and **p < 0.01.