Assessing the sensitivity and specificity of cognitive screening measures for people with Parkinson's disease

INTRODUCTION

While cognitive impairment is a recognised feature of Parkinson's disease (PD), few studies have evaluated the validity of brief cognitive screening measures compared to a comprehensive neuropsychological assessment. This studies aim was to evaluate the sensitivity and specificity of the Mini-Mental State Examination (MMSE), Modified Mini-Mental State Examination and Dementia Rating Scale (DRS-2) to detect cognitive impairment in individuals with PD.

METHOD

Fifty-eight participants were administered the MMSE, 3MS, DRS-2 and a neuropsychological battery. ROC analyses were conducted to assess their effectiveness in classifying cognitive impairment.

RESULTS

None of the three measures demonstrated good sensitivity or specificity to detect single domain cognitive impairment. For detecting impairment on two or more cognitive domains, the MMSE and DRS-2 yielded excellent sensitivity (88%) and specificity (78% and 76% respectively), at cut-off scores of 28 and 136 respectively. The 3MS demonstrated excellent sensitivity (88%) and good specificity (60%) at cut off score of 94.

CONCLUSION

The MMSE and DRS-2 have excellent discriminant ability to classify multi-domain cognitive impairment in PD, however, their ability to detect more focal cognitive impairment is limited. Given that focal domain may be an indicator that could be useful in early detection of cognitive impairment for people with PD, this finding has implication for the use of these measures as screening tools in clinical practice.

Neuropsychological Function and Driving Ability in People with Parkinson's Disease

In this study the association between cognitive symptoms of PD and driving performance was investigated by examining the correlation between neuropsychological test performance and driving simulator behavior. Eighteen participants with PD and 18 healthy participants in a matched comparison group completed a range of neuropsychological measures. These data were correlated with driving simulator performance results from an earlier study. Significant correlations were found between several measures of neuropsychological test performance and driving behavior in participants with PD. In contrast, few significant correlations were obtained in the comparison group. Results suggest that executive difficulties in people with PD such as working memory, planning and set shifting are associated with reduced tactical level driving performance such as speed adaptation and complex curve navigation. Impaired information processing, visual attention and visual perception in people with PD appears associated with reduced operational level driving performance, such as reacting to road obstacles and maintaining constant lane position. Few correlations were found between measures of physical mobility and psychomotor speed with driving measures. Overall, this study highlights the important role of cognitive function in driving performance within the PD population. Comprehensive assessment of cognitive function should be included when assessing driving competency in people with PD.