STRAIGHTJACKET & TIE by Eugene Stein (Ticknor & Fields: $19.95; 277 pp.). Bert Rosenbaum, late in this first novel, sees the police arrive at his parents' apartment to transport his older brother, Philip, to the Bronx State Psychiatric Center. Philip, a diagnosed schizophrenic, has been acting more and more demented, to the point that Philip has finally agreed, at his family's urging, to voluntary commitment. Bert, who over the previous year has become friends with three green aliens from the planet Debbie, finally articulates, silently, the idea that lies at the core of this novel: "Philip went crazy so I wouldn't have to." "Straightjacket & Tie" is a heartfelt book, apparently drawing heavily on the real lives of Eugene Stein and his brother, but it isn't much more than that; the subplots, involving Bert's homosexual coming-of-age and his interactions with aliens, are conventional and strained, respectively. Philip is by far the most interesting character in the book, especially when he's writing his nonsense poetry or thinking about baseball. He's ready to admit to emotional difficulties, but believes they would disappear if the Yankees and Mets were in the World Series--meaning that his parents shouldn't be pressuring him to go to a psychiatrist but Met management to get decent pitching.