Moving forward: the psychomotor syndrome in schizophrenia

Date: 13 May 2015

Venue: UAntwerp- Campus Drie Eiken, Building Q, Promotiezaal - Promotiezaal - Universiteitsplein 1 - 2610 Wilrijk

Time: 6:00 PM

Organization / co-organization: Faculty of Medicine and Health Sciences

PhD candidate: Lise Docx

Principal investigator: Prof M. Morrens & Prof B. Sabbe

Short description: PhD defence Lise Docx - Faculty of Medicine and Health Sciences


Psychomotor disturbances are core characteristics of schizophrenia. Nevertheless, our understanding of this symptom clusters remains rather scarce. These disturbances are qualitative (e.g. deficits in motor sequencing) as well as quantitative (e.g. diminished motor activity). 

The diversity of psychomotor abnormalities seen in patients with schizophrenia is reflected in the variety of motor signs and symptoms that can be found in the literature. Overall, the qualitative signs and symptoms are classified under four syndromes: extrapyramidal signs (EPS), catatonia, psychomotor slowing and (motoric) neurological soft signs. However, it remains unclear what the associations between these syndromes are, since they are seldom studied together. 

In this thesis, it was found that a phenomenological association exists between (retarded) catatonia, clinically observed psychomotor slowing and parkinsonism (an EPS) on the one hand and between motoric NSS on the other hand. Quantitative psychomotor activity was not found to be associated with qualitative psychomotor performance. Besides, it was pointed out that the measurement technique (i.e. observation scale or instrumental test) might have an impact on the associations found. Since quantitative psychomotor activity could not be predicted by the quality of psychomotor functioning, the second part of this these aimed to investigate possible neuropsychological and neurobiological correlates of the diminished motor activity and motivation seen in patients. It was investigated whether a deficit in the cost-benefit analysis between physical effort and reward value (i.e. effort based decision making) is involved in the motivational symptoms of patients with schizophrenia. 

Results of this study showed that the decisional process of patients was not disturbed nor was there an association between physical effort based decision making and diminished motor activity or motivational symptoms in patients. However, these results should be interpreted with caution, especially since recent studies do suggest a role of (aspects of) effort based decision making in the motivational deficits of schizophrenia patients. On a neurobiological level, a significant association between the amount of motor activity and white matter microstructure complexity in brain regions associated with cognition and motivation was found.