Motor overflow in schizophrenia

Hoy, Kate E.; Fitzgerald, Paul B.; Bradshaw, John L.; Farrow, Maree; Brown, Timothy L.; Armatas, Christine A.; Georgiou-Karistianis, Nellie

doi:10.1016/j.psychres.2003.12.005

« Previous Next »Psychiatry Research
Volume 125, Issue 2 , Pages 129-137, 15 February 2004

Motor overflow in schizophrenia

Kate E. Hoy
- Experimental Neuropsychology Research Unit, Psychology Department, Monash University, Clayton 3800, Victoria, Australia
- Corresponding author. Tel.: +61-0416-021-896; fax: +61-3-9905-3948
Paul B. Fitzgerald
- Alfred Psychiatry Research Center, The Alfred and Monash University Department of Psychological Medicine, Australia
John L. Bradshaw
- Experimental Neuropsychology Research Unit, Psychology Department, Monash University, Clayton 3800, Victoria, Australia
Maree Farrow
- Experimental Neuropsychology Research Unit, Psychology Department, Monash University, Clayton 3800, Victoria, Australia
Timothy L. Brown
- Alfred Psychiatry Research Center, The Alfred and Monash University Department of Psychological Medicine, Australia
Christine A. Armatas
- Deakin University, School of Psychology, Geelong, Australia
Nellie Georgiou-Karistianis
- Experimental Neuropsychology Research Unit, Psychology Department, Monash University, Clayton 3800, Victoria, Australia

Received 27 January 2003; received in revised form 6 October 2003; accepted 16 December 2003.

Abstract

The occurrence of motor dysfunction as a sign of schizophrenia, in addition to being a side effect of medication, has received considerable support in recent years. The current study aimed to systematically investigate both the presence and pattern of one such motor dysfunction, motor overflow. It was hypothesised that patients with schizophrenia would show significantly greater motor overflow than controls, and that the pattern of motor overflow occurrence would also vary significantly between the groups. A finger flexion task was used to examine the presence and pattern of motor overflow. Subjects were asked to maintain target forces, using either their index or small finger, representing 25, 50 or 75% of the maximum strength capacity for whichever finger was performing the task. Patients were found to exhibit significantly greater motor overflow than controls. There were also significant findings with respect to the patterns of motor overflow produced, specifically in regards to fine motor control and performance variability. In summary, patients differed significantly from controls in both the degree and pattern of overflow exhibited.

Keywords: Motor dysfunction, Mirror movements, Psychiatric illness