One hundred and fifty people died in March last year when co-pilot Andreas Lubitz flew flight 9525 into a mountain-side in the French Alps after locking the pilot out of the cockpit.
French investigators held a news conference in France this morning as the report into the crash's cause is published.
It comes after some of the families of the victims of the crash, who had advance sight of the report, voiced concerns.
Investigators told the news conference a doctor had recommended that Lubitz should be treated in a psychiatric hospital two weeks before the disaster, Sky News reported.
Lubitz had begun to show symptoms that could be consistent with a psychotic depressive episode in December 2014 and consulted several doctors over the following months, none of whom alerted aviation authorities or his employer, the spokesman for France's BEA revealed.
Families of the victims have been told Lubitz saw 41 doctors for his condition in recent years.
Under German law, none of the doctors was able to alert his employers to his state of mind.
The investigators have recommended that as a result of what happened, there should be new world rules on medical reporting about pilots and regular screening of pilots' mental health.
Another recommendation was that, because the existing regime of pilot testing may be "inadequate", regular special examinations are carried out on pilots with a "medical history of mental disorder".
Other recommendations included a suggestion that colleagues should be able to safely and securely provide feedback on pilots' mental states.