Psychological horror dealing with the mysteries of the human mind is also popular in recent years.
Literal
Recent-years [at-では], human-psychology [genitive-の] mysteries [object-を] handle psycho-horror [also-も] popular is.
A pop-culture commentary. サイコホラー is a loanword compound: サイコ (psycho, from English 'psychological') + ホラー (horror) = 'psychological horror' as a horror subgenre. 扱う ('to handle, to deal with, to treat, to cover') is a useful all-purpose verb for 'having as one's subject.' 近年 ('recent years') is a formal/written time reference. では topicalizes the temporal setting. The ~も on サイコホラー adds this subgenre to an implied list of recent horror trends.