Amnesia
Memory Loss, Forgetfulness
noun
A healthy bit of forgetting symptoms means you might have amnesia.
健忘症 often refers to short-term memory loss, either full or partial, but some people might also use it in a sort of joking way for everyday forgetfulness.
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.
健忘症は不治の病なんでしょうか。
Is amnesia an incurable disease?
去年、有田さんは一過性の健忘症になってしまった。
Last year, Mr. Arita suffered from transient amnesia.
お医者さんに健忘症の疑いがあると言われました。
The doctor told me that he suspected amnesia.
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.