While the actress does say here that the dark subject matter of the film did have an impact on her, it was only in a way that has happened to her before because of the way that she inhabits her characters.
She just needed to talk herself out of the dark place that character brought her.
While the new remake of Suspiria that recently came out is being touted by many as being a truly disturbing and bizarre horror movie, any indication that it caused Dakota Johnson to be disturbed is going too far.