From cell- and animal-based approaches, it has been shown that the viral-mediated overexpression of NRN1 in different models (unpredictable stress-induced rat depression model, mice exposed to low-frequency electromagnetic fields and an Alzheimer’s disease model Tg2576 mouse) prevents the atrophy of dendrites and spines and improves associated behaviours, such as anxiety, depression, deficits in novel object recognition, learning and memory [31,32,33]. This evidence concerns the gene NRN1 and major depressive disorder.