Association Between the Enriched Environment Level and Serum Brain-Derived Neurotrophic Factor (BDNF) in Patients...

Major Depressive Disorder (MDD) is a neuropsychiatric condition whose neurobiological characteristics include alterations in brain plasticity, modulated by Brain-Derived Neurotrophic Factor (BDNF). In animal models, environmental enrichment promotes neuroplasticity and reduces depressive-like behaviors. In humans, we proposed to assess the level of Enriched Environment (EE) using a questionnaire that includes different domains of the EE (cognitive, social, and physical), which we named the EE Indicator (EEI).

To determine the relationship between the level of EE and serum BDNF in participants with MDD and healthy controls.

Participants with MDD without antidepressant treatment and healthy controls were recruited, and their EE level and serum BDNF concentration were determined looking for correlations between their clinical characteristics and the cognitive, social, and physical activities according to the EEI.

A total of 25 participants were recruited, of which 6 participants with MDD and the same number of controls were selected in a paired manner. Although no differences were found in the concentration of BDNF between the groups, positive correlations were observed between cognitive EE and BDNF (r = 0.62, p = 0.035), as well as negative social EE and the Hamilton Depression Rating Scale (HDRS) (r = -0.86, p = 0.001). The sum between cognitive and social EE showed a positive correlation with the serum concentration of BDNF (r = 0.34, p = 0.0451).

The level of EE is potentially modulating the presence and severity of MDD at a clinical level, but it can also influence at a neuroplastic level through promoting or limiting the concentration of BDNF.