Facing concerns about his own family history of Alzheimer's, CNN chief medical correspondent Dr. Sanjay Gupta visits preventive neurologist Dr. Richard Isaacson to have his own risk for dementia assessed in the CNN documentary "The Last Alzheimer's Patient." Watch the full documentary on CNN's "The Whole Story" premiering on May 19 at 8p ET/PT and streaming on MAX on June 18. | CNN

CNN went on the air for the first time 40 years ago on June 1, 1980. Here’s a look back at some of the most defining stories from the last four decades. https://cnn.it/372dRy9 | CNN International

"I happen to be one of those so-called people that are labeled as a liberal on civil rights, but oppose busing." In a 1981 CNN interview, Joe Biden says that he opposed busing to desegregate schools and that he supported efforts to cut back on courts' ability to order busing. His opposition to busing in the 1970s is facing renewed scrutiny after California Sen. Kamala Harris criticized him for his position at the 2020 Democratic debate. https://cnn.it/2ZShgL0 | CNN Replay