Tanya Frank, a Londoner living in Los Angeles, wrote an essay in The New York Times titled “Unmoored by a Psychotic Break” about her son’s diagnosis with schizoaffective disorder in 2009. Her book about the next decade of her and her son’s life, Zig-Zag Boy: A Memoir of Madness and Motherhood (W.W. Norton), chronicles how psychiatric illness can redefine the relationships in and beyond a family.