Subjective and objective cognition in early-stage, treatment-naïve Parkinson's disease: Relationships with mood

Subjective cognitive complaints (SCCs) are common in Parkinson's disease (PD), yet the relationship among nonmotor symptoms remains understudied in early-stage, treatment-naïve populations. We examined interrelationships among SCCs, mood symptoms, and cognition in early-stage, treatment-naïve PD. We hypothesized that SCCs would relate to executive functioning and processing speed, and these relationships would be moderated by mood.

Cross-sectional baseline data analyzed 250 individuals (169 men, 81 women; aged 50-84 years) in the Parkinson's Progression Markers Initiative. Moreover, t tests and Pearson correlations assessed associations among SCC group status, mood symptoms, and cognition. Ordinary least squares regression evaluated whether mood moderated the relationship between SCC group status and cognition.

Participants in the higher SCC group were more likely to demonstrate processing speed impairment (14% vs. 5.3%, p = .02). Those in the higher SCC group exhibited poorer memory (p = .035, d = .41) and processing speed (p = .001, d = .21) and reported more depression symptoms (d = .84) and state (d = .72) and trait anxiety (ps < .001, d = .85). A significant interaction revealed that individuals in the higher SCC group with elevated state anxiety demonstrated worse memory (ps < .05). No other mood moderation effects were found.

In early-stage, treatment-naïve PD, more SCCs corresponded with worse mood symptoms and worse processing speed and memory. Memory performance was worse when both higher SCCs and elevated state anxiety are present, but mood did not moderate higher SCCs' relationship with other domains. SCCs may be early indication of neurocognitive vulnerability. Longitudinal research is warranted to determine how mood symptoms impact SCCs' utility for predicting cognitive decline. (PsycInfo Database Record (c) 2026 APA, all rights reserved).