On the intercellular level, there are two main mechanisms of neurodegeneration as a result of injury:

-In retrograde degeneration, a neuron is injured close to the cell body, which initiates cell death of the neuron. If the entire injured neuron atrophies or dies, the neurons that were previously connected to the injured neuron may experience degeneration as well in a process known as transneuronal degeneration.

-In anterograde degeneration, a neuron is injured farther from the cell body along its axon. The part of the axon that is severed from the neuron is degraded, but the axon may regrow, and new axonal sprouts can connect with postsynaptic cells by the help of CAMs and other factors.