Neuropsychological profile of psychogenic jerky movement disorders: importance of evaluating non-credible cognitive performance and psychopathology.

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.