Complex sentence: Eugen Bleuler defined and differentiated subtypes of schizophrenia at the turn of the century, and found catastrophic schizophrenia to affect 10-15% of schizophrenics.
Split into simpler sentences: Eugen Bleuler defined and differentiated subtypes of schizophrenia at the turn of the century. Clinical psychology, 2003, page 74 In his studies of schizophrenia, he found catastrophic schizophrenia to affect 10-15% of schizophrenics.