PG-13 | 1h 51min | Drama, Romance | 11 September 2015 (USA) It’s not uncommon to see many outstanding books adapted into movies. However, the same can’t be said for documentaries being turned into narrative cinema, let alone by the same director. But British director Morgan Matthews has done just that. Teaming up with screenwriter James Graham, he has turned his 2011 documentary “X+Y” (titled “Brilliant Young Minds” in the United States) into the fascinating 2014 narrative film “A Brilliant Young Mind.” The film follows the trials and tribulations of Nathan (Edward Baker-Close as a child and later Asa Butterfield), an autistic child who is unusually gifted in mathematics. Unfortunately, he struggles when it comes to communicating with others. Of his parents, Julie and Michael (Sally Hawkins and Martin McCann), only his father seems to be able to break through Nathan’s shell by using his goofy sense of humor. Michael …