Symptom overlap between schizophrenia and bipolar mood disorder: Diagnostic issues

Although the Kraepelinian classification paradigm is widely used, observations of overlapping boundaries among the symptoms associated with bipolar disorder and schizophrenia are beginning to challenge this dichotomy. The objective of this research was to explore the symptoms of individuals diagnosed with schizophrenia and with bipolar mood disorder in order to determine the frequency of symptom overlap. One hundred patients of a psychiatry ward were divided into two main groups based on their diagnosis—schizophrenia or bipolar mood disorder. Chi-square analyses were used to determine whether the symptoms measured in this study differed between individuals diagnosed with schizophrenia and those diagnosed with bipolar mood disorder. The results suggest that both positive/manic symptoms and negative/depressive symptoms are present in individuals diagnosed with schizophrenia and with bipolar mood disorder and, consequently, they do not present a reliable means of differentiating between these two groups. These findings have many implications for the ways in which mental illness is conceptualized and classified. Treatment efforts and interventions may be enhanced if a more dimensional approach to diagnosing mental illness is utilized.