Objective: To characterize cognitively normal PD patients who endorse cognitive complaint, and to assess their cognitive performance over time.

Background: PD patients are at a high risk for developing cognitive impairment. Subjective cognitive complaints are common in seemingly unaffected patients and little is known about the value in subjective complaints to herald objective decline. We hypothesized that PD patients who report a subjective cognitive complaint develop objective cognitive decline and dementia more often than PD patients without a subjective complaint.

Methods: We followed 141 PD patients with normal cognition (NC) at baseline for one to two years with neuropsychological testing, and ratings of functional abilities. The presence of a cognitive complaint was queried by a trained researcher. An expert panel classified all patients after each visit as having NC, MCI, or dementia following MDS-recommended criteria.

Results: Seventy-six PD patients with NC had a cognitive complaint (+CC) and 65 did not (-CC). +CC had significantly lower scores on the Trail Making Test A (t(136)=2.29, p=0.02, Cohen’s d=0.39) and Symbol Digit Modalities Test (SDMT) (t(133)=2.09, p=0.04, d=0.35) than -CC patients. Global cognitive measures and demographic variables did not differ between groups. +CC demonstrated significantly lower scores on questionnaires assessing everyday functional abilities related to cognition than -CC (Brief Penn Parkinson’s Daily Activities Questionnaire, (t(105)=2.83, p<0.05 for knowledgeable informant version and t(120)=4.43, p<0.05 for patient-reported version) and at trend level for general activities of daily living (Alzheimer’s Disease Cooperative Study-Activities of Daily Living, (t(116)=1.80, p=0.07). +CC patient’s scores on the SDMT and ADCS-ADL declined more rapidly over time than did -CC scores (F(1, 88)=4.462, p<0.05, and F(1, 73)=4.763, p<0.05 by RM-ANOVA).

Conclusions: +CC patients with normal cognition perform worse on measures of processing speed than -CC patients with normal cognition. In addition, both +CC patients and their knowledgeable informants report greater functional impairment at baseline and these deficits increased over time compared with -CC patients. The presence of a cognitive complaint in PD patients with normal cognition could indicate subtle decline that is otherwise undetectable in global cognitive testing and may have long-term prognostic significance.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/cognitive-complaint-in-parkinsons-disease-patients-with-normal-cognition/