Dopamine synthesis capacity and tau pathology differentially modulate rest-to-task functional network dynamics

In cognitively unimpaired older adults, higher tau burden in PiB+ individuals is linked to a task-induced collapse of network segregation across large-scale brain networks.

• Why it matters: Aging alters how brain networks shift from rest to task, and dopamine dysregulation and AD pathology may affect these dynamics differently.
• What they did: Young and older adults completed resting-state and task fMRI plus PET for dopamine synthesis capacity ([18F]fluoro-m-L-tyrosine), amyloid status ([11C]Pittsburgh Compound-B; PiB−/PiB+), and tau pathology ([18F]flortaucipir).
• The result: PiB+ participants showed reduced rest-to-task network stability, and tau burden predicted reduced task-related segregation, while dopamine effects on stability were present in young adults but attenuated with age and absent in PiB+ groups.

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