Former Disney star Demi Lovato has revealed that she suffered three strokes, a heart attack and was left with permanent brain damage following her almost-fatal overdose three years ago.

The singer-songwriter is set to speak about her difficult experiences in her new documentary Demi Lovato: Dancing with the Devil.

The trailer for the documentary dropped on YouTube on Wednesday, with the US pop sensation opening up about her long-standing addiction struggles.

Speaking at the documentary's Television Critics Association panel with director Michael D. Ratner, Demi revealed the full extent of her problems she has dealt with following the ordeal.

"I was left with brain damage, and I still deal with the effects of that today. I don't drive a car, because I have blind spots on my vision," the hitmaker said.

"And I also for a long time had a really hard time reading. It was a big deal when I was able to read out of a book, which was like two months later because my vision was so blurry.

"I dealt with a lot of the repercussions and I feel like they are still there to remind me of what could happen if I ever get into a dark place again," she added.

"I'm grateful for those reminders, but I'm so grateful that I was someone that didn't have to do a lot of rehabbing. The rehabbing came on the emotional side."

Demi also claims in the trailer that doctors predicted Lovato would die within 5 to 10 minutes.

The documentary will look at her rise to fame as a child to her battles with mental health and sobriety. Fans will also get an insight into her recent, short-lived engagement to Max Ehrich in the four-part feature.

'Sorry Not Sorry' singer Demi relapsed in 2018 after being sober for a six years, almost losing her life in the process. After her overdose, the artist spent two weeks recovering in Cedars-Sinai Medical Center in Los Angeles. She then returned to rehab for a number of weeks until she felt well enough to leave.

Demi Lovato: Dancing with the Devil will arrive on March 23rd on YouTube.