Bassist Marco Coti Zelati was absent for a small portion of the tour due to illness but collected ideas while at home recovering.

During an interview on 6 April 2016, male vocalist Andrea Ferro said, "all the material that was coming from him was ultimately pretty intense, a little heavier and a little darker than usual and we really liked this new direction he was taking.

He has a studio in the south so nothing really changed in the song-writing process but obviously the ideas were different and the inspiration was different, and there was a bit of time between Delirium and Broken Crown Halo (2014) so the life experiences were different.

[13] The official recording process began in December 2015 and finished in February 2016 at BRX Studio in Milano, Italy, by Marco Barusso who also mixed the album.

Myles Kennedy of Alter Bridge and Mark Vollelunga of Nothing More as well as Diego Cavallotti and Marco Barusso played the guitar solos on various tracks.

Following their 2014 release, Broken Crown Halo, which was described by the band as "a cinematic album, about a dark vision of a near future",[15] Delirium takes on a conceptual theme of insanity occurring inside an asylum.

The band have described the album as "horrors that we must face in everyday life by exploring the unknown, and to one day, hopefully find the cure.

[18] Discussing the opening track "The House of Shame" during an interview with Metal Hammer, Scabbia described it as a "story of a real sanatorium in the States.

On 8 April 2016, the band officially announced that they would return to North America for the "Delirium Worldwide" tour to promote the album.

Anyone who pre-ordered a digital copy from iTunes Store or Amazon Music was immediately able to download "Ghost in the Mist", "Delirium" and "The House of Shame".

Members of the band, including Scabbia and Coti-Zelati have visited various Best Buy locations in the United States to hide autographed guitar picks inside the stores.

Scabbia has posted a number of videos on her personal Facebook page to give fans clues as to what stores the picks are located at as well as where they are hidden.

Axl Rosenberg, one of the founders of MetalSucks said "If fans bristle at any aspect of Delirium, it will be the album's relative paucity of more upbeat, Karmacode-esque material.