Why do neurons shrink with age? (even though they don't die)

#1

Like, what makes them lose dendritic spines and shrink their axons over time? (lack of maintenance? disruptions in axonal transports?) is having too many autophagy involved in this?

Synaptic loss seems more impt than dendritic shrinkage

#2

https://rupress.org/jcb/article/220/6/e202105008/212106/Synapses-have-autophagy-under-controlSynapses-have