Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:This result supports the hypothesis of a stronger role for BDNF during childhood when, in addition to the presence of lower BDNF levels (Casey et al., 2009), neuronal networks dependent of neural plasticity (Angelucci et al.
Category: