To dream that you are a mentally challenged person, indicates that you are having feelings of self-doubt. You are afraid of being left out or left behind by others.
To see a mentally challenged person in your dream, suggests that someone around you is feeling ignored or overlooked. Perhaps you have failed to listen to what they have to say.
[1]1. Self-esteem and confidence.
2. Feelings of being socially “slow,” somewhat alienated.
[2]Figurative of one who acts as such, and names may be substituted
[3]