FIGURE 1.

Decline of axonal transport is a hallmark of neuronal ageing. (A) Timeline of selected milestones in the study of axonal transport during ageing. In bold, studies of particular interest for the scope of this review. (B) Decline of axonal cargo transport during ageing is a common feature across different neuronal populations of several model organisms, although the precise mechanisms of transport decline are not well understood. Not all cargo transport equally declines during ageing (refer to main text for further details) and the motility of many essential cargoes, for instance mRNPs, has not yet been investigated (red question marks). In addition to transport decline, cargoes such as mitochondria undergo an age-dependent functional decay (purple mitochondria). Transport decline correlates with decreased cellular function: can the decline in cargo motility be reversed in an attempt to improve neuronal health during ageing?