Mental health articles

The Schizoaffective Continuum

Although our diagnostic system treats schizophrenia and the affective disorders as unrelated diseases, there is a continuum from schizophrenia to affective disorders, patients with schizoaffective symptoms outnumber those with purely schizophrenic or purely affective symptoms. Crow concludes that ‘‘no objective genetic boundaries can be drawn’’ between predominantly affective and predominantly schizophrenic patients.

The theoretical challenge of the schizoaffective disorders is well recognized. In schizoaffective disorder with manic symptoms, the DA theory of schizophrenia combined with Depue’s DA theory of mania points to the obvious possibility that some vulnerability to schizophrenia (a primary schizophrenia deficit) combines with the high level of BAS-based DA activity in mania to produce schizophrenic symptoms.

The continuum from schizophrenia to mania reflects the relative contributions of specific genetic liability for schizophrenia and the BASbased general liability. A relatively large liability for schizophrenia requires only a modest amount of BAS-DA activation and thus frequently would present as schizoaffective mania, mainly the schizophrenic subtype. In contrast, a more moderate liability for schizophrenia requires a strong BAS activation (more clearly a manic episode) to reach the threshold for symptom production, thereby presenting as the schizoaffective manic, mainly the manic subtype. Intermediate cases would show a more or less equal manifestation of schizophrenic and manic symptoms. Thus, the dopamine theories of schizophrenia and mania offer an explanation for the fusion of the boundaries of schizophrenia and the affective disorders. It should be noted that Braden proposed a very similar model. In schizoaffective disorder with depressive symptoms, a similar suggestion can be made for a nonspecific contribution of depression to general liability for schizophrenia.

Assuming that depression usually involves aversive arousal (from BIS activation), depression can be seen to fit the proposal cited before that aversive arousal contributes to the appearance of schizophrenic symptoms and a negative symptom pattern. Moreover, the hopelessness associated with depression will depress reward-seeking behavior and especially promote the anhedonic features of the negative symptoms. In support of this perspective, the symptoms of depression so overlap with the negative symptom pattern in schizophrenia that it is difficult to distinguish between the two