Missy Elliott Has Graves Disease

Missy Elliott explains why she's been out of the spotlight of late, during her upcoming episode of "Behind the Music."

According to the Hollywood Reporter, the rapper/producer explains that her absence was largely due to her ongoing battle with Graves' disease, an autoimmune disorder that affects the thyroid. Elliott reportedly tells People Magazine, in an upcoming issue, that she's had the disease since 2008.

"I was [driving and] trying to put my foot on the brake, but my leg was jumping. I couldn't keep the brake down and almost crashed," Elliott said. "I couldn't write because my nervous system was so bad -- I couldn't even use a pen."

Brad Abramson, executive producer for Elliott's "Behind the Music," said the recording artist also discusses "in detail" the sexual abuse she experienced as a child.

The episode airs Wednesday, June 29 at 10 p.m.