Table 2: Results on the relationship between BDNF and depression.

Authors Aim Sample Methods Instruments Results
Shimizu et al. [10] Determine how BDNF levels are related to treated and untreated depressive conditions and how these levels differ between individuals with MDD and controls. 16 individuals with MDD without antidepressant treatment.
17 individuals with MDD on antidepressant therapy.
50 controls.
Patients were assessed using the Hamilton Scale for depression (HAM-D). BDNF levels were accessed through the ELISA method. Hamilton Depression Rating Scale (HAM-D) Low levels of BDNF were found in untreated depressive patients when compared to the treatment group and the control group.
Siuciak et al. [34] Determine how the administration of BDNF can produce an antidepressant effect in two animal models of depression. Male rats treated in the laboratory. Infusion of BDNF into the animals' brains for a week. - An antidepressant effect was observed after administration of BDNF in the two animal models of depression tested in the study. The increase could be mediated by increased activity in monoaminergic systems.
Martinotti et al. [5] Investigate the effects of Agomelatine on serum BDNF levels in a sample of depressed patients. 27 individuals with MDD. Serum levels of BDNF were achieved by the ELISA method at the beginning of treatment after two weeks and after 8 weeks of treatment. Hamilton Depression Rating Scale (HAM-D).
Snaith-Hamilton Pleasure Scale.
Patients showed an increase in BDNF levels after two weeks of treatment with Agomelatine.

Note: MDD = Major Depressive Disorder.