Many specific age-related degenerations have no name and remain uncategorized, poorly understood, even undiscovered. All likely stem from a small range of types of accumulated damage, but nonetheless it should serve as something of a wakeup call that scientists continue to uncover these sorts of things: "Multiple reports have documented an age-related loss, estimated at about 10% per decade, of the pigmented neurons in the substantia nigra. This is associated with motor dysfunction, including bradykinesia, stooped posture and gait disturbance. As microglia are activated by cell death and neuromelanin pigment, we hypothesized that there should be a significant microglial reaction in normal aging human substantia nigra. ... older subjects, the percentage of substantia nigra area occupied by microglial bodies and processes was significantly greater than for younger subjects ... The marked microglial reaction in normal aging human substantia nigra, together with the previously reported 35-80% pigmented neuron loss, indicates the presence of a powerful pathologic process that may be additive with specific age-related neurodegenerative diseases, including Parkinson's disease."