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:The impairment of mPFC in BD may be due, in part, to the symptoms of prominent cognitive and behavioral problems, including difficulties in making appropriate decisions (Minassian et al. 2004; Van der Gucht et al. 2009), which accompanied with bipolar mania.
Category: