Amnesia
Loss Of Memory
noun
A healthy bit of forgetting symptoms means you might have amnesia.
けんぼうしょう
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
健忘症に苦しんでいる親戚がいます。
I have a relative who is suffering from amnesia.