Addle (verb)

1. To become confused or muddled.
2. To make confused or muddled.

Origin:

From old english adelian "to grow rotten, go bad".

Examples:

1. The constant noise addled his mind.
2. The heat was addling her thoughts.
3. Being stuck in traffic addled her nerves.
4. The complexity of the task addled his brain.
5. The constant interruptions addled his concentration.