Can a dedicated circuit share a neutral?

It depends on:

• what you are calling a dedicated circuit
• Whether there is ANY possibility that the neutral could be required to carry a load in excess of the rating of the wire.

First we have to make certain that we're talking the same language, second we have to consider the fire hazard involved. (although, if we're looking at safety, we would need to reverse the two)

The simple answer is No.

The term "dedicated circuit" is not defined in the code. But in practice the term refers to a circuit that is run for a particular purpose, often to one piece of equipment or receptacle (outlet). Sharing a neutral contradicts the principle of a dedicated circuit.

Sharing a neutral would expose the circuit to electrical elements such as harmonics. A dedicated circuit is intended to avoid such problems.