Having trouble remembering a new name or doing more than one task at a time? Cognitive decline starts after a person's 20s, resulting in memory loss and other cognitive struggles. The good news is that several activities, including playing games, promote healthy aging and may prevent or delay some diseases. A study at the University of California, Berkeley, found evidence that an area in the brain used in playing bridge stimulates the immune system. Researchers suggest that is because players must use memory and sequencing.