Screening for Cognitive Impairment in Parkinson's Disease

Sunset in Blanchard, OK courtesy of Dr. Tim Yates

There is a significant need for improvement in the tools available for screening for cognitive impairment in a variety of disorders in neuroscience medicine.

The Mini-Mental State Examination Score (MMSE) is a widely used 30-item scale for screening dementia and other neurological conditions.

However, the MMSE has some significant weaknesses for use in the clinical setting.

Jin Qiao and colleagues from China recently published a study testing the MMSE to screen for cognitive problems in a group of patients with Parkinson's disease (PD).

A score of 24 or lower is commonly used as a marker for evidence of cognitive impairment in adults from typical educational backgrounds. This would mean individuals with scores above 24 would typically be screened as not having significant cognitive impairment.

In the Chinese study, a series of PD subjects with scores over 24 were studied in detail with more intense neuropsychological testing including the Montreal Cognitive Assessment (MoCA). The MoCA tests seven cognitive domains including visuospatial/excutive, naming, attention, language, abstraction, delayed recall and orientation.

The key findings from this study included:

• 65% of the subjects screened cognitively normal with the MMSE had evidence of cognitive impairment on the MoCA (score <26)
• Cognitive impairment domains in screened impaired PD subjects included: visuospatial/executive, attention, language, abstraction and delayed recall
• Analysis of the MMSE screening data supported raising the threshold for screening impairment in PD subjects from a score of 24 to a score of 28 in higher educated samples

This is an important study with implications for practice assessment and management of patients with PD. The study supports using the MoCA over the MMSE for screening cognitive impairment in PD.

Additionally, this study highlights the need to study screening tools in specific disease populations. Screening thresholds and best cognitive screening practices may be disease specific.

More information and a paper copy of the MoCA can be found here.

Readers with more interest in this study can access the free full-text manuscript by clicking on the PMID link in the citation below.

Photo of sunset in Blanchard, Oklahoma is provided courtesy of Dr. Tim Yates

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Qiao J, Zheng X, Wang X, Lu W, Cao H, & Qin X (2015). Neuropsychological profile in Chinese patients with Parkinson's disease and normal global cognition according to Mini-Mental State Examination Score. International journal of clinical and experimental medicine, 8 (8), 13755-61 PMID: 26550322