Singer Whitney Houston's death last month from accidental drowning from the effects of cocaine use and heart disease throws bright light on a dark corner of the world of celebrities who wrestle with substance abuse. Living on the edge: Whitney Houston's longtime drug habit eventually played a part in her death. Whitney Houston's longtime drug habit eventually played a part in her death. The toll of celebrity addiction — to street drugs, prescription drugs, alcohol or a mix — is long and mournful, and seems particularly heavy right now...