LE BOURGET, France (AP) — French air accident investigators spent a year analyzing remains and interviewing experts about how and why Germanwings co-pilot Andreas Lubitz intentionally crashed a passenger jet into the French Alps, committing suicide and killing 149 others. Here are some key findings from the investigation agency BEA:

ANTIDEPRESSANTS

Lubitz had been taking antidepressants around the time of the crash that he hadn't declared to his employers, despite requirements to do so.

His remains had traces of anti-depressive medications Citalopram and Mirtazapine as well as the sleeping aid medication Zopiclone. The U.S. National Library of Medicine notes on its entry for Citalopram that children and young adults who take the drug can become suicidal "especially at the beginning of your treatment and any time that your dose is increased or decreased."

U.S., British, Australian and Canadian rules allow pilots to fly while using antidepressants under some circumstances and under medical supervision, the report says. It recommends that European authorities adopt similar measures, to encourage pilots to get treatment for depression — and to tell their airlines when they do so.

DOCTORS' SILENCE

A private doctor referred Lubitz, who had suffered from depression in the past, to a psychiatric clinic two weeks before he crashed the plane, warning of a possible "psychotic episode." Another doctor gave him a sick note covering the day of the crash. He consulted three dozen others in the weeks prior.

That made him unfit to fly on March 24, 2015. But no one reported that information to authorities or his airline. That's because of strict German medical privacy laws, meant to protect patients' confidentiality. Doctors risk prison terms if they violate the rules, except in extraordinary situations.

Because those rules protect patients' privacy even after they die, multiple doctors also refused to speak with crash investigators. The German air accident agency said that means they were unable to determine with any certitude what exactly Lubitz was suffering from.

MEDICAL PRIVACY

Those German privacy rules come under intense scrutiny in the BEA report. Its top international safety recommendation is that world aviation bodies define new rules to require that doctors warn authorities when a pilot's mental health could threaten public safety.

The report says a factor in the crash was a "lack of clear guidelines in German regulations on when a threat to public safety outweighs" patient privacy.

New rules should limit legal risks to doctors when they report a public safety risk, the BEA said. It says German authorities in particular should remind doctors that they can breach medical confidentiality. The BEA also suggests defining what can be considered as "imminent danger" and "threat to public safety" with regards to pilots' health issues.

But Johann Reuss of Germany's air accident investigation agency said "there is no need to change the law" and suggested that authorities should instead focus on giving doctors checklists to prevent similar scenarios with pilots.

COCKPIT

Lubitz locked the captain out of the cockpit in order to crash the plane. He was able to do that after door code systems were put in place after the Sept. 11 attacks to prevent hijackers from seizing the controls.

The BEA says there's no reason to change current cockpit rules, with the "risk of illicit attacks in flight being considered more threatening" than pilot suicide.

"A lockage system cannot be created to prevent threats coming from outside and inside the cockpit," said Arnaud Desjardin, head BEA investigator on the Germanwings crash.

Some airlines and regulators issued changes after the Germanwings crash to require at least two people to be in the cockpit at any given time to prevent similar crashes. BEA chief Remi Jouty noted, however, that pilots had committed suicide with another person in the cockpit in the past.