Identifying parkinsonism in mild cognitive impairment.

Area of Science:

• Neurology
• Cognitive Science

Background:

• Clinical parkinsonism is crucial for diagnosing mild cognitive impairment with Lewy bodies (MCI-LB).
• Accurate identification of parkinsonism in MCI can be challenging.
• A five-item scale from the Unified Parkinson's Disease Rating Scale (UPDRS) is used for parkinsonism assessment in dementia.

Purpose of the Study:

• To evaluate the efficacy of the five-item UPDRS scale in identifying parkinsonism in individuals with MCI.
• To compare the diagnostic performance of the five-item scale in MCI versus dementia.

Main Methods:

• Two cohorts of MCI participants (n=146) underwent physical examination, UPDRS assessment, and [123I]-FP-CIT SPECT imaging.
• Participants were categorized based on clinical parkinsonism (P+/P-) and dopaminergic imaging (D+/D-).
• The five-item scale summed UPDRS scores for rest tremor, bradykinesia, action tremor, facial expression, and rigidity.

Main Results:

• The five-item scale demonstrated high diagnostic accuracy (AUROC 0.92-0.97) for differentiating P+D+ from P-D- participants across cohorts.
• A 3/4 cut-off achieved optimal sensitivity (83-100%) and specificity (82-88%) in MCI, outperforming the dementia-derived 7/8 cut-off.
• The scale was ineffective in differentiating abnormal (D+) from normal (D-) dopaminergic imaging.

Conclusions:

• The five-item UPDRS scale is effective for identifying parkinsonism in MCI.
• A lower threshold (3/4) is more suitable for MCI than the threshold used for dementia.
• The scale aids in diagnosing MCI-LB by detecting clinical parkinsonism.