Just over a year after being discovered unresponsive at her Atlanta home, the cause of Bobbi Kristina Brown's death has been revealed.

The 22-year-old daughter of Whitney Houston died from a combination of drug intoxication and drowning, a statement from the Fulton County Medical Examiner's Office confirmed this morning.

Bobbi was discovered face down in a bathtub in her suburban Atlanta townhouse on January 31, 2015. She remained on life support in hospital until June of last year, before being moved to hospice care where she passed away on July 26th.

A full autopsy report will soon be released, after a judge yesterday granted a media request for the results to be unsealed.

According to the statement released today, Bobbi had marijuana and alcohol in her system at the time of the incident, along with medications used for sedation or to treat anxiety.

TMZ report that the drugs in her system included "a cocaine-related substance called benzoylecgonine, benzodiazepines (prescription anti-anxiety meds) and morphine.

Bobbi's boyfriend Nick Gordon was last year served with a civil lawsuit by the Brown/Houston family in relation to his treatment of Bobbi before her death.

Mr Gordon, who recently completed a stint in rehab, was accused of punching his girlfriend in the face, knocking out a front tooth and dragging her upstairs by her hair.

It is also alleged that he "routinely" transferred funds "into an account controlled solely by him" without having her consent or authorisation.

Speaking to the media four months after her death, Bobbi's aunt Pat Houston said her family had known that Bobbi was in trouble with drugs and alcohol, and were hoping to send her to rehab before the January 2015 incident.

"When we really found out that Krissy [Bobbi Kristina] was in trouble, we were really making plans to do something about it… but it came too late," she said in an Entertainment Tonight interview recorded last November.

Many fans noted that Bobbi's death bore a sad resemblance to that of her mother Whitney.

The music icon was discovered submerged in a bathtub at the Beverly Hills Hilton in February 2012, and was pronounced dead at the scene.