Christiane F. (1981) is a film directed by Uli Edel about Vera Christiane Felscherinow's struggles with Heroin use as a young teenager. Although this is one of the most grim films I've seen, as it's about a 13 year old girl whose life quickly descends into addiction and darkness, it's an important and true story.
The film is shockingly realistic in its portrayal of Christain F.'s struggles, which you can also learn about in her 2013 written autobiography, Christiane F. – My Second Life . Christaine F. grew up in West Berlin during the 1970's, and she was a huge David Bowie Fan. The film features Bowie as himself and as the soundtrack composer, which added to the film's cult status. The trailer's embedded above.
Images from Youtube