Psychomotor planning is deficient in recent-onset schizophrenia

Background: Psychomotor slowing is regarded as an important clinical phenomenon in schizophrenia and simple graphic tasks consistently revealed deficits in the (implicit) planning and execution of motor actions in patients with chronic schizophrenia. The aim of the present study is to test the hypothesis that such deficits are already present in patients with recent-onset schizophrenia. Methods: Psychomotor performance and several aspects of movement planning were analyzed in 36 patients with recent-onset schizophrenia and a group of 33 matched healthy controls. Participants were required to draw patterns varying in complexity in three different figure-copying tasks, match and draw simple symbols in the Digit Symbol Substitution Test (DSST) and connect target circles with varying orientations in a newly developed Line Sequencing Task. Results: Relative to the controls, the patients showed significantly longer initiation times when the patterns in the copying tasks became more complex, suggesting increased difficulty in movement planning. Overall, they were not slowed in the execution stages. In the cognitively more demanding DSST, the patients were significantly slowed in both the initiation and movement phases. Moreover, they selected less optimal movement directions in the Line Sequencing Task. Conclusions: Psychomotor planning deficits are already present in the early stages of schizophrenia and involve deficient planning but intact motor action. Planning difficulties can be detected in motor sequences as well. The results indicate that the cognitive deficit in schizophrenia also affects the implicit planning of very simple movements.