In an article titled ?Addiction and Depression: The Vicious Cycle? featured in the Health section of About.com, Dr. Sack discusses the connection between addiction and depression. He begins the piece by explaining that while it is not always clear whether addiction and depression comes first ? or vice versa ? there is one important factor to note: ?When substance use co-occurs with mental illnesses such as depression, the issues can feed off each other, causing negative effects to multiply.? Read the full article online.