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:Importantly, brain atrophy measures based on T1w images are shown to correlate with the amount of tau deposition and neuropsychological deficits, thus validating its use as a biomarker of Alzheimer’s disease (AD) (Frisoni et al., 2010).
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