““There is some empirical support for the notion that schizophrenia and bipolar disorder exist along a psychosis continuum, with some patients having more affective features and others having more psychotic features. On the other hand, the contribution by Jauhar and coauthors indicates that along one important dimension, that of dopaminergic dysfunction, schizophrenia and bipolar disorder are similar; there is a hint that change over time is what distinguishes them,” he wrote. “Clinical experience is perhaps more consistent with a model including not one but two dimensions, namely, affective and psychotic. … In this framework, the abnormality reported by Jauhar and coauthors is associated with the psychosis dimension and could serve to quantify this dimension in future studies, advancing the research agenda toward ultimately developing a more valid classification system for psychotic disorders.””
So if the psychotic symptoms are mostly explained via the dopamine hypothesis, what type of dysfunction is responsible for the affective symptoms?