Table 2 Study Characteristics
From: Association between BDNF levels and suicidal behaviour: a systematic review and meta-analysis
Author (year) | Study design and sample groups | Participants (n) | Definition of suicidal behaviour | Type of BDNF measurement (units) | Mean (SD) BDNF levels | p-value (difference between groups) | Variables adjusted for |
|---|---|---|---|---|---|---|---|
Postmortem Brain Studies | |||||||
Banerjee et al. (2013) | Case–control Cases of suicide vs. non-psychiatric healthy controls | Suicide: 21 Control: 19 | Completed suicide | Brain – hippocampus (pg/ml) | Suicide: 19.5a Control: 44a | <0.001 | None |
Dwivedi et al. (2003) | Case–control Cases of suicide vs. non-psychiatric controls | Suicide: 27 Control: 21 | Completed suicide | Brain – PFC, hippocampus (optical density) | PFC Suicide + MDD: 0.94 (0.22) Suicide + other psychiatric disorder: 0.88 (0.28) Control: 1.61 (0.39) Hippocampus Suicide + MDD: 1.04 (0.20) Suicide + other psychiatric disorder: 1.03 (0.22) Control: 1.71 (0.44) | <0.001 <0.001 | None |
Karege et al. (2005) | Case–control Cases of suicide vs. non-psychiatric controls | Suicide: 30 Control: 24 | Completed suicide | Brain – PFC, hippocampus, entorhinal cortex (ng/g) | Hippocampus Drug-free MDD: 17.7 (2.9) Drug-free others: 16.8 (3.1) Drug-treated MDD: 23.3 (2.2) Drug-free controls: 24.5 (3.6) PFC Drug-free MDD: 13.8 (2.6) Drug-free others: 12.7 (2.6) Drug-treated MDD: 17.9 (2.9) Drug-free controls: 17.5 (3.0) Entorhinal cortex Drug-free MDD: 14.1 (2.1) Drug-free others: 13.4 (2.4) Drug-treated MDD: 12.9 (2.3) Drug-free controls: 13.4 (2.5) | <0.001 <0.002 Not significant | PMI, age |
Maheu et al. (2013) | Case–control Depressed individuals (divided into suicide victims vs. non-suicide deaths) vs. non-psychiatric controls | Depressed suicide (12) Depressed non-suicide (10) Control (14) | Completed suicide | Brain – BLA, CeA (optical density) | BLA Depressed suicide: 1.19 (0.80) Depressed non-suicide: 1.67 (1.42) Control: 1.08 (0.34) CeA Depressed suicide: 0.95 (0.20) Depressed non-suicide: 1.87 (1.30) Control: 0.97 (0.16) | Not significant Not significant | PMI, brain pH, age |
CSF Studies | |||||||
Martinez et al. (2012) | Case–control Depressed patients vs. non-depressed patients | Depressed (18) Non-depressed (25) | Suicidal ideation | CSF (pg/ml) | NA | Correlation between BDNF concentration and SSI score: r = 0.62, P = 0.033, n = 12 | None |
Serum BDNF Studies | |||||||
Deveci et al. (2007) | Case–control Suicide attempters vs. non-suicidal MDD patients vs. healthy controls | Suicide (10) Non-suicidal MDD (24) Healthy controls (26) | Suicide attempt | Serum (ng/ml) | Suicide: 21.2 (12.24) Non-suicidal MDD: 21.2 (11.3) Control: 31.4 (8.8) | Suicide vs. healthy controls: 0.004 Suicide vs. MDD: not significant | None |
Grah et al. (2014) | Case–control MDD patients vs. PD patients vs. AD patients vs. healthy controls | Suicide (96) Control (106) b | Suicide attempt | Serum (ng/ml) | RDD c Suicide: 11.8 (8.88–14.73) Control: 12.8 (10.83–14.78) PD Suicide: 10.7 (7.04–14.26) Control: 15.7 (10.29–21.02) AD Suicide: 12.6 (9.63–15.58) Control: 15.4 (12.04–18.77) | 0.07 0.003 0.009 | Age, sex, therapy |
Huang & Lee (2006) | Case–control Schizophrenic patients vs. healthy controls | Suicidal schizophrenic (11) Non-suicidal schizophrenic (115) Healthy control (96) | Suicide attempt | Serum (ng/ml) | Suicidal schizophrenic: 14.60 (7.02) Non-suicidal schizophrenic: 14.16 (6.94) | 0.841 | None |
Liang et al. (2012) | Case–control Depressed patients (with or without suicide attempt) vs. healthy controls | Suicidal depressed (31) Non-suicidal depressed (34) Healthy control (30) | Suicide attempt, suicidal ideation | Serum (ng/ml) | Suicidal depressed: 57.3 (9.2) Non-suicidal depressed: 76.0 (25.7) Healthy control: 113.8 (44.4) | Suicide attempt: <0.01 Suicidal ideation: <0.01 | None |
Park et al. (2014) | Cross-sectional MDD patients | Suicidal MDD (18) Non-suicidal MDD (33) | Suicide attempt | Serum (ng/ml) | Suicidal MDD: 21.93 (24.71) Non-suicidal MDD: 24.71 (7.7) | 0.3 | None |
Pinheiro et al. (2014) | Cross-sectional Postpartum women | History of suicide attempts (12) No suicide history (178) | Suicide attempt, suicidal ideation | Serum (ng/ml) | Suicide: 2.11 (1.42) Control: 2.37 (1.26) | 0.6 Linear regression of PPAD and suicide risk: −0.912 (−1.73– -0.09) p = 0.029 | Previous psychiatric treatment, stressful life events during pregnancy |
Plasma BDNF Studies | |||||||
Kim et al. (2007) | Case–control Suicidal depressed patients vs. non-suicidal depressed patients vs. healthy controls | Suicidal depressed (32) Non-suicidal depressed (32) Control (30) | Suicide attempt | Plasma (pg/ml) | Suicidal depressed: 430.5 (397.0) Non-suicidal depressed: 875.80 (663.02) Control: 889.4 (611.3) | 0.002 | None |
Lee et al. (2007) | Case–control Depressed patients vs. healthy controls | Suicidal depressed (28) Non-suicidal depressed (49) Control (95) | Suicide attempt | Plasma (pg/ml) | Suicidal depressed: 386.61 (362.39) Non-suicidal depressed: 689.66 (404.65) Control: 819.20 (347.05) | <0.001 | None |
Lee & Kim (2009) | Case–control Suicidal depressed patients vs. non-suicidal depressed patients vs. healthy controls | Suicidal depressed (20) Non-suicidal depressed (20) Control (20) | Suicide attempt | Plasma d (pg/ml) | Suicidal depressed: 713.04 (236.56) Non-suicidal depressed: 693.98 (347.84) Control: 709.05 (172.12) | 0.971 | None |