Schizophrenia as a “Polythetic Construct” • No single characteristic symptom • Many symptoms, all present in some, not present in all • Manifestations in thinking, emotion, interpersonal relationships • A multisystem disease
What are the Characteristic Symptoms of Schizophrenia? • Depends upon whom you ask • Depends upon theoretical construct • Depends upon what you mean by characteristic Common? Specific? Core?
Kraepelin: The Borders of Schizophrenia …it is certainly possible that its borders are drawn at present in many directions too narrow, in others perhaps too wide.
Boundaries of the Concept • Schizoaffective Disorder • Psychotic Mood Disorders • Nonpsychotic disorders Schizotypal Personality Simple Schizophrenia
“Good Prognosis Schizophrenia” • Prominent affective symptoms • Acute onset • Family history of affective disorder • Good premorbid function • Presence of insight
Narrowing of Concept: Rationale • Risk of tardive dyskinesia • Risk of erroneously treating mood disorders with neuroleptics • Risk of self-fulfilling prophesies of poor outcome • Risk of political abuse
Single or Multiple Illnesses • Whether dementia praecox in the extent here delimited represents one uniform disease, cannot be decided at present with certainty. -- Emil Kraepelin
Heterogeneity: Competing Models • Single disease entity: multiple sclerosis • Multiple disease entities: mental retardation • Multiple domains of psychopathology
Single Disease Entity • A single illness • A single cause that produces diverse manifestations • Possible mechanism: process producing multiple brain lesions
Multiple Disease Entities • “The group of schizophrenias” • Multiple causes Purely genetic forms, e.g. phenylketonuria Purely environmental forms, e.g. virally induced Multifactorial forms • Manifestations reflect site of injury and time of the maturational process
Multiple Domains • Multiple dimensions of psychopathology e.g., psychotic, disorganized, negative • Different mechanism for each dimension • Disease process A dimension A • Disease process B dimension B • Disease process C dimension C • Mixed clinical presentation due to multiple disease processes