?Taking on an unusual role for the child of a sitting mayor, Chiara de Blasio, 19, the first daughter of New York City, traveled to Maryland with her parents on Tuesday to accept an award from the Health and Human Services Secretary, Kathleen Sebelius, and published an emotionally raw essay online about her struggles with depression and addiction. Ms. de Blasio, who last year revealed that she had sought treatment for alcohol and drug abuse, was recognized by the federal Substance Abuse and Mental Health Services Administration for serving as an example of hope for other young adults, at a ceremony in Prince George’s County on children’s mental health. During the ceremony, Ms. de Blasio said that a year ago she would not have been able to imagine “standing before you today as a sober and healthy young woman.” Her parents, Mayor Bill de Blasio and his wife, Chirlane McCray, introduced her, and the mayor spoke emotionally about the alcoholism that ultimately contributed to his own father’s suicide. “In my own life, in my own family, we faced these demons before,” Mr. de Blasio said. “My own father was an alcoholic. He could not, unfortunately, tragically, find his way to this kind of help, this kind of recovery. But his granddaughter could. And she did.” Since the start of Mr. de Blasio’s mayoral campaign, his two children have played more prominent roles than most political offspring. Ms. de Blasio’s brother, Dante, who is now 16, starred in what was widely regarded as the most effective advertisement of the mayoral race, saying that his father would end police discrimination against minorities and be “a mayor for every New Yorker.” And Mr. de Blasio’s campaign relied heavily on images of him with his wife and children as a close and happy family. The campaign worked hard to keep Ms. de Blasio’s personal struggles from being reported. It released a carefully crafted video on Christmas Eve that featur