Directional Bias in Line Orientation Test Errors in Parkinson's Disease.

OBJECTIVE: Value in evaluating error subtypes on visuospatial line orientation tests has been reported. Directional bias metrics for line orientation test errors represent easily quantifiable data that have not previously been studied. We evaluated whether patients with a clinical condition known to affect visuospatial functioning (Parkinson's disease [PD]) exhibited unique directional error patterns on the RBANS Line Orientation test relative to other neuropsychology-referred patients. METHOD: We compared overall directional bias in errors, directional bias by line location (left or right line and visual field), and absolute error rates (regardless of direction) by line location in a retrospective sample of patients with PD and a sample of neuropsychology-referred patients without PD. Groups were roughly matched on age, education, gender, and overall level of cognitive impairment. RESULTS: Patients with PD exhibited higher rates of leftward bias in errors, both overall and for the left stimulus line in each pair. Directional bias error scores better predicted PD versus non-PD group status than RBANS Line Orientation raw scores. Classification accuracy data for these variables were modest in the entire sample but stronger in a subsample of patients with mild levels of overall cognitive impairment. CONCLUSIONS: Directional bias metrics for line orientation tests represent easily quantifiable data with potential theoretical and clinical value. In our sample, patients with PD made more left-biased line orientation errors than other neuropsychology-referred patients. By themselves, directional bias scores may have limited diagnostic potential, but they may be useful in diagnostic classification models and may have implications for clinical care.

Effects of severity of dementia on a symptom validity measure.

While prior research has shown symptom validity tests (SVTs) to have clinical utility with cognitively impaired individuals, these studies typically excluded those diagnosed with mild cognitive impairment (MCI) and dementia. The purpose of this study was to determine the utility of an SVT, the Test of Memory Malingering (TOMM), in those with MCI and moderate to severe dementia. Participants included 30 cognitively intact individuals (Control Group), 28 diagnosed with MCI (MCI Group), and 31 diagnosed with moderate to severe dementia (Moderate-Severe Group). The range of Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) Total Standard Scores were then calculated for each group and all participants were administered the TOMM. Analysis of covariance (ANCOVA) revealed no significant differences on TOMM Trail 2 scores between the Control Group and the MCI Group. While all group means were above established cut-off scores, approximately 20% of participants in the Moderate-Severe Group failed the TOMM according to established criteria. Results suggest that the TOMM may be an appropriate test of effort in older adults diagnosed with MCI, but is not recommended for assessing potential malingering in those with at least moderate to severe dementia.