Information processing abnormalities in schizophrenia and bipolar disorder

Information processing abnormalities in schizophrenia and bipolar disorder Objective: Patients with bipolar disorder and schizophrenia exhibit abnormalities in attention, memory, working memory, verbal/visual learning and executive functions. However, many of the tests fail to detect slight changes in cognitive performance due to ceiling effect. It was aimed to determine sensitivity and specificity of the tests that measure information processing in schizophrenia and bipolar disorder in this study. Method: Thirty four patients with schizophrenia, 35 patients with bipolar disorder according to DSM-IV and 33 healthy control subjects matched for age, education level and gender were enrolled to the study. For clinical assessments Scale for the Assessment of Positive Symptoms, Scale for the Assessment of Negative Symptoms, Hamilton Depression Rating Scale, Young Mania Rating Scale, Clinical Global Impression Scale and Abnormal Involuntary Movements Scale were used. All participants performed a battery consisting of tests measuring information processing including Adult Memory and Information Processing Battery (AMIPB), Trail Making Test (TMT) Form A and B, Digit Symbol Coding Task (DST) and Auditory and Visual Reaction Time Tests (RTT). Results: The schizophrenia group had significantly lower performance than the healthy control group in all tests and lower performance than the bipolar disorder group in AMIPBA and B tests, TMT A and B tests. The bipolar disorder group had lower performance than the healthy control group only in DST test. The AMIPB A and B tests were the most sensitive and specific tests in the ROC analysis. Conclusion: Changes in cognitive function might be better monitored by the tests whose sensitivity and specificity are higher. Since psychiatric disorders are highly heterogeneous, measurement tools are important for precise measurements.