How did Nathaniel Anthony Ayers get schizophrenia in the soloist?

In "The Soloist," Nathaniel Anthony Ayers developed schizophrenia, a mental illness that often emerges in late adolescence or early adulthood, though the exact cause is not fully understood. The film suggests that his condition may have been exacerbated by a combination of genetic predisposition and environmental factors, including the pressures of his music career. Ayers's struggles with mental health ultimately led to his descent into homelessness and a disconnection from his earlier life as a talented musician.