Final answer:
Schizophrenia is defined by persistent psychotic symptoms along with negative symptoms. Schizoaffective disorder includes both psychotic and mood disorder symptoms concurrently, while psychotic symptoms in depressive or bipolar disorder appear exclusively during mood episodes. The primary differentiating feature is the presence and timing of mood symptoms in conjunction with psychosis.
Step-by-step explanation:
To differentiate Schizophrenia from Schizoaffective disorder and depressive or bipolar disorder with psychotic features, one must consider the timing and nature of the symptoms. Schizophrenia is characterized by persistent psychotic symptoms, such as hallucinations or delusions that are present for at least six months, along with negative symptoms and functional impairment.
Schizoaffective disorder is differentiated by the presence of mood disorder symptoms (either depressive or bipolar) alongside psychotic symptoms, where mood episodes and psychotic features occur concurrently and psychotic symptoms must also be present for at least two weeks without significant mood symptoms. Depressive or bipolar disorder with psychotic features is primarily diagnosed on the basis of mood disturbances, where psychotic symptoms are directly tied to mood episodes, either during manic or depressive states.
While cognitive impairment and treatment response to antipsychotic medication can provide additional information regarding the nature of a psychotic disorder, they are not the primary distinguishing features. Instead, the duration and intensity of psychotic symptoms (a) and the presence of a concurrent mood disorder define the diagnostic differences among these conditions.