Objective: To explore the predictive value of non-motor symptoms on the cognitive decline of patients with Parkinson’s disease (PD) in a three-year follow up.

Background: Patients with PD are at increased risk of cognitive decline. It is clinically important to identify predictors of cognitive decline. The existing evidence suggests that non-motor symptoms of PD may be critical determinants of PD prognosis. Non-motor symptoms often occur in clusters, which may reflect different phenotypes of the disease.

Method: Sixty-two consecutive patients with PD (60% men; mean age=68±11; education=7±4; disease duration=8±6; levodopa equivalent dose=784mg±583; UPDRS-III Off=31±11 and On=20±8) performed the Dementia Rating Scale-2 (DRS-2) and answered the Non Motor Symptoms Scale (NMSS). Participants were evaluated at baseline and after an approximate 3-year period (mean= 1092 days±64). The 5th percentile of demographically adjusted norms (adjusted for age and education based on normative data) was used to identify cognitive impairment on the DRS-2 total score. Cognitive decline at follow up was defined as a DRS-2 total adjusted score decline greater than 0.5. Chi-square, Mann-Whitney, and Multiple Logistic Regressions were applied for data analyses.

Results: Seventeen patients (27%) had cognitive impairment at baseline and 35 patients (56%) showed cognitive decline at follow-up. Cognitive decline was related with older age (p=0.016), longer disease duration (p=0.020), higher levodopa equivalent dose (p=0.022), and more non-motor symptoms on NMSS total score (p=0.024) in the first evaluation. No significant associations (p>0.05) were found with sex, education, age at disease onset, UPDRS-III OFF and ON, or cognitive impairment at baseline. Regarding the 9 NMSS domains, patients with cognitive decline at follow up had more attention/memory (domain 5; p=0.012) and gastrointestinal tract (domain 6; p=0.009) complaints at baseline. Gastrointestinal symptoms (adj odds=1.234, p=0.013) and specifically constipation (adj odds=1.244, p=0.041) remained statistically associated with cognitive decline even when age, disease duration and levodopa equivalent dose were taken into account.

Conclusion: The study results revealed that gastrointestinal symptoms are significant predictors of future cognitive decline in PD. These findings may provide additional support to the concept of “gut-brain axis” in PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/gastrointestinal-symptoms-predict-cognitive-decline-in-parkinsons-disease/