(CNN) Kathy Griffin's mom, Maggie Griffin, who became something of a fan favorite through her daughter's Bravo reality show, " Kathy Griffin: My Life on the D-List," is suffering from dementia, the comedian said Thursday in an emotional Instagram post. Griffin said she felt the need to be honest about her mother's condition with her followers because many have asked why she hadn't shared video or photos of her recently. "I've always been honest with you all, but this one is really hard," she wrote.