Resting-state networks, functionally connected brain regions, are canonically investigated with resting-state functional-MRI. 11C-UCB-J is a recently developed PET tracer that binds and visualizes synaptic vesicle protein 2A. The aim is to identify networks of coherent 11C-UCB-J covariation patterns using independent component analysis. We find modest similarity between five 11C-UCB-J PET-based synaptic density sources and rs-fMRI template RSNs. In several sources, there are varying rates of age-related change in subject loading weight, consistent with functional changes in RSNs and age-related gray matter decline. Our findings support the independency of such networks and potential physiological links between synaptic density and brain function.