What is mental illness, and what causes it? Can it be mere stress? Recreational drug use? A cheating girlfriend? A vitamin imbalance?

Mark Vonnegut proposed all these possibilities in his 1975 bestseller ?The Eden Express.? A memoir of counter-culture, coming of age, and living with schizophrenia, The New York Times said it was “required reading for those who want to understand insanity from the inside.”

But in his new book, ?Just Like Someone Without Mental Illness, Only More So,? Vonnegut’s views on his mental illness have changed slightly. For one, he’s not so sure he was ever schizophrenic.

A respected physician, graduate of Harvard medical school, and son of the late Kurt Vonnegut, Dr. Mark Vonnegut joins us from Boston.