BDNF and depressive symptom measurement: Following Fisher Exact Test with a p value threshold set at 0.05, the canonical pathway analysis module of IPA identified a list of pathways with relevance to neuropsychiatric disorders (Fig. 8a) such as protein kinase A signaling, phospholipase C signaling, glucocorticoid signaling, ERK/MAPK signaling, neurotrophin signaling, corticotropin releasing signaling, GABAergic signaling and glutamatergic signaling; all of them are known for their role in depression and suicidal behavior.