A comparison of schizophrenia, schizoaffective disorder, and bipolar disorder: Results from the Second Australian national psychosis survey.

INTRODUCTION

It remains uncertain whether schizoaffective disorder (SAD) is a discrete diagnostic entity, is a variant of either a psychotic mood disorder such as bipolar disorder (BDP) or schizophrenia (SCZ), or exists on a spectral continuum between these disorders. The present study examined whether SCZ, SAD, and BDP differed qualitatively on demographic and clinical variables based on a large Australian dataset.

METHODS

This study examined data from the Australian Survey of High Impact Psychosis (SHIP), in which 1469 of the 1825 participants in who had an ICD-10 diagnosis of SCZ (n=857), SAD (n=293), and BDP (n=319) were assessed across a broad range of variables.

RESULTS

When compared to patients with SCZ, those with SAD reported more current delusional and thought disorder symptoms, a greater number of lifetime depression, mania, and positive symptoms, and fewer negative symptoms. Relative to the BPD group, the SAD group were younger, endorsed more current positive, delusional, and thought disorder symptoms, fewer lifetime mania symptoms, more lifetime psychotic, hallucination, and delusional symptoms, and recorded lower premorbid IQ scores. Compared to patients with BPD, those with SCZ were significantly younger, endorsed more current psychotic and hallucination symptoms, fewer lifetime depression and mania symptoms, more lifetime psychotic, hallucination, and delusional symptoms, reported more negative symptoms and had lower premorbid IQ and psychosocial functioning scores.

LIMITATIONS

Validated psychometric measures of psychotic or mood symptoms were not used.

CONCLUSION

This pattern of results is consistent with the conceptualisation of a spectrum of disorders, ranging from BDP at one end, to SAD in the middle, and SCZ at the other end.