Neuropsychological profile of psychogenic jerky movement disorders: importance of evaluating non-credible cognitive performance and psychopathology
- Carolien E J Heintz1,
- Mirjam J van Tricht1,
- Sandra M A van der Salm1,
- A F van Rootselaar1,
- Danielle Cath2,
- Ben Schmand1,3,
- Marina A J Tijssen4
- 1Department of Neurology, Academic Medical Centre, University of Amsterdam, Amsterdam, Netherlands
- 2Department of Clinical and Health Psychology, Altrecht Outpatient Anxiety Services, Utrecht University, Utrecht, Netherlands
- 3Department of Psychology, University of Amsterdam, Amsterdam, Netherlands
- 4Department of Neurology, University Medical Centre Groningen, University of Groningen, Netherlands
- Correspondence to Dr Marina A J de Koning-Tijssen, Movement Disorders, Department of Neurology AB 51, University Medical Centre Groningen (UMCG), PO Box 30.001, 9700 RB Groningen, The Netherlands;
- Received 17 October 2012
- Revised 27 December 2012
- Accepted 9 January 2013
- Published Online First 16 February 2013
Background Psychogenic movement disorders are disorders of movements that cannot be explained by a known neurological disorder and are assumed to be associated with psychiatric symptoms such as depression and anxiety.
Objective To examine the neuropsychological profile of patients with psychogenic movement disorders.
Methods We examined cognitive functioning using neuropsychological tests in 26 patients with clinically established psychogenic jerky movement disorders (PMD). We included 16 patients with Gilles de la Tourette syndrome (GTS) who served as a patient control group, in addition to 22 healthy control subjects. Non-credible test performance was detected using a Symptom Validity Test (SVT). Psychopathology was also assessed.
Results Apart from a worse performance on a verbal memory task, no evidence of neuropsychological impairments was found in our PMD sample. Interestingly however, patients with PMD reported more cognitive complaints in daily life and performed worse on the SVT than the two other groups. Patients with GTS did not report, or show, cognitive impairments. In patients with PMD, we found associations between verbal learning, SVT performance and severity of depression and anxiety complaints.
Conclusions We conclude that some patients with PMD show non-credible cognitive symptoms. In contrast, no evident cognitive impairments were present in patients with PMD or GTS. Our study underlines the importance of assessment of non-credible response in patients with PMD. Additionally, non-credible response might aid in the differentiation of PMD from other movement disorders.