The most common criticism of Walker Percy's novels is that they are repetitive.
Although The Thanatos Syndrome is different from any of his other books, some of themes do echo throughout his fiction. This is a testimony to the novelist's fervent belief in the importance of highlighting certain key problems and issues, and to his belief that their continued presence in our lives demands continued fictional (and nonfictional) scrutiny.
Percy, who himself had medical and pathology training, described this kind of philosophical book as a "diagnostic novel." Although the emphasis is clearly on the book's ideas and moral themes, The Thanatos Syndrome is also a medical thriller. As such, it was almost inevitable that the author would revisit a theme that he dealt with on numerous occasions in earlier novels: the relationship between the "abnormal" and the rest of the nominally healthy and sane society.