antimnemonic
/æntɪmˈnɒnɪk/Definitions
1. noun
A factor or influence that opposes or hinders memory or recollection.
“The loud music served as an antimnemonic to her attempt to remember the lyrics.”
2. adjective
Opposing or tending to hinder memory or recollection.
“The antimnemonic effects of the medication were a concern for the researchers.”