Autism, attention deficit-hyperactivity disorder, bipolar disorder, major depressive disorder and schizophrenia all share several genetic risk factors, according to a major study.

BBC: Five psychiatric disorders 'linked'

Studies suggest that most cases of bipolar disorder start with depressive episodes and that many young people who develop severe depression will eventually go on to have a manic episode.

CNN: How can I help my despairing son?

Most commonly, the mood disorder accompanying the schizophrenic features is either bipolar disorder (bipolar-type schizoaffective) or depression (depressive-type schizoaffective).

CNN: Schizoaffective disorder

Taylor's fascination with psychology grew out of her own family's experience with mental illness: her father was diagnosed as manic depressive, and in high school, she herself was diagnosed with bipolar disorder, though she was not medicated.

NPR: Intersections: Inside the Mind of Lili Taylor