Laura Dern made one final vow to her mother, Diane Ladd, before her death from lung disease. "I made a promise to my mom that I would continue to honor her legacy, and her commitment and service to teaching and advocating for other families going through an ILD," Dern, 58, told People on Wednesday, January 28, of raising awareness for idiopathic pulmonary fibrosis (IPF), a form of interstitial lung disease (ILD). IPF is a progressive lung disease that occurs "when lung tissue becomes damaged and scarred - what's known as fibrosis," per Mayo Clinic.