Nonmotor Symptoms Reduce Quality of Life in Parkinson′s Disease Depending on Disease Stage and Age at Onset

In this observational study, which presents a secondary analysis related to a previously published work from our group, we aimed to examine the impact of nonmotor symptom (NMS) burden on HR‐QoL in 154 outpatients with Parkinson′s disease (PD), ranging from mild to moderate‐advanced disease stages, with a specific focus on motor disease progression and age at onset (AAO). To this purpose, NMS burden was measured using the NMS scale (NMSS), overall HR‐QoL using the Parkinson′s Disease Questionnaire‐39 (PDQ‐39), and sleep disturbances using the Parkinson′s Disease Sleep Scale‐2nd version (PDSS‐2). The scores of the three scales were correlated with motor impairment and the amount of dopaminergic therapy. Furthermore, NMSS, PDQ‐39, and PDSS‐2 scores were compared between early onset PD (EOPD, AAO ≤ 50) and late‐onset PD (LOPD, AAO > 50), as well as between “poor sleepers” and “good sleepers” based on the validated PDSS‐2 cutoff of 18/60. We found that total NMSS, PDSS‐2, and PDQ‐39 scores significantly increased with advancing disease stage. EOPD patients had lower NMSS and PDSS‐2 global scores compared to LOPD patients, despite the latter having longer disease duration and similar PDQ‐39 scores. The NMSS global score correlated with each single domain of the PDQ‐39, with the strongest associations observed in the “mobility,” “activity of daily living,” and “cognition” domains. Over one‐third of patients were classified as “poor sleepers” (PDSS‐2 ≥ 18) and exhibited higher NMSS and PDQ‐39 total scores compared to “good sleepers.” In conclusion, this study enlightens the increasing impact of NMS and sleep disturbances on patients′ HR‐QoL with disease progression and across different AAO, underscoring the need to address such modifiable factors to alleviate the burden of the disease.