Impaired Trail-Making Test-B performance in patients with acute schizophrenia is related to inefficient sequencing of planning and acting

Abstract

In order to investigate the functional basis of the frequently described deficits of schizophrenia patients in Trail Making Test B (TMT-B) performance, the performance process was analyzed based on the interaction of eye and hand movements. In a longitudinal design, 23 acute schizophrenia patients, 17 acute depressive inpatients, and 21 healthy controls were assessed twice within 4 weeks. Computer versions of both TMT-A and TMT-B were used, which require to connect different targets with a cursor, with concurrent infrared oculography. In both TMT-versions, schizophrenia patients demonstrated poorer performance and longer “planning periods”—as defined by fixations outside the cursor area—containing more fixations, which were stable over time. However, these “planning fixations” were only also longer in duration during TMT-B and differed in time and context of their occurrence compared with healthy controls. Schizophrenia patients demonstrated more fixations while the cursor rested between targets. Significant correlations with performance time gave evidence that it is important for short planning periods to be performed parallel to ongoing connection of targets, to obtain a satisfactory result. No relationship between “planning variables” with psychopathology and medication could be found. Accordingly, poorer TMT-B performance in schizophrenia patients was found to be related to insufficient sequencing of planning and acting, which appears to be a trait-like characteristic. Though depressive patients also performed poorer in TMT-B, they did not differ from either of the other groups in the main process variables, which may hint to different underlying causes of the performance deficits in both groups of patients.