P.1.j.025 Sensitivity of the tests measuring information processing in schizophrenia and bipolar disorder

Abstract

Purpose: Schizophrenia and bipolar disorder are two major psychiatric illnesses that may have pathophysiological common points. Although the relationships between cognitive functions, symptoms and functionality differ for schizophrenia or bipolar disorder, and remain to be clarified, it’s known that cognitive dysfunction is a good candidate to be a predictor of functioning in both disorders [1]. The importance of the cognitive dysfunction in psychiatric disorders has been substantially increasing, but we still need more sensitive and appropriate assessment tools [2]. Most instruments or tests assess only one domain, representing a single task. This narrow span is useful when examining a specific domain that is heavily impaired. In psychiatric disorders, however, most subjects are only slightly impaired and those tools with low sensitivity lack reliability and sensitivity in determining slight impairments. This study aims to evaluate capabilities of cognitive tests used to evaluate information processing in schizophrenia and bipolar disorder. Methods: Thirty-five patients with bipolar disorder (age 34.74+ 8.71 years, m/f: 18/17) and 32 schizophrenia patients (age 39.97+9.43 years, m/f: 23/9) enrolled into the study. Clinical examinations were performed with Scale for the Assessment of Negative Symptoms (SANS) and Scale for the Assessment of Positive Symptoms (SAPS), Young Mania Rating Scale (YMRS), Hamilton Depression Rating Scale (HDRS) and the Abnormal Involuntary Movement Scale (AIMS). Cognitive evaluations included the Stroop Test (ST), Trail Making Test (TMT), Digit Span Test, Digit-Symbol Substitution Test (DSS), auditory and visual Reaction Time Test (RT) and Adult Memory and Intelligence Processing Battery (AMIPB). The AMIPB has raw scores and adjusted scores according to motor speed of subjects. The t test and Pearson’s correlation tests were used for statistical analyses. Results: Visual RT, TMT-B, digit span, DSS test and 1, 2, 3 and 5th subtests of the ST did not differ between groups. Auditory RT (p = 0.004), TMT-A (p = 0.024), ST 4 (p = 0.040) tests differed between groups. There was significant difference between groups in all subtests of the AMIPB. Motor (p = 0.001), total raw score (p< 0.001), and adjusted scores (p< 0.001) of the AMIPB-A and total raw score (p = 0.002), motor speed (p = 0.013) and adjusted (p = 0.001) scores differed between groups. The AMIPB showed correlations to all other cognitive measures, both in schizophrenia and bipolar disorder groups with strong significance. Discussion: The AMIPB discriminated the schizophrenia and bipolar disorder groups. These results suggest that among many different tests to measure information processing, the AMIPB is a sensitive test in quality and quantities of speed and accuracy for psychiatric disorders. The battery also include working memory demands, therefore it evaluates different aspects of information processing. Information processing is related to basic components of cognition including working memory and executive functions (judgment, decision making, etc.). Although all other tests include properties of one aspect of basic components of information processing, the AMIPB has interactions with different basic components of cognition. This wealthy of interactions may provide broader portfolio of capabilities and greater sensitivity for the battery. The AMIPB is a highly sensitive and consistent test for information processing evaluations in schizophrenia and bipolar disorder.