B-26 Predictors of Cognitive Decline Over a 2-year Follow up: Olfaction and Scans Without Evidence of Dopaminergic Deficit Status (SWEDD)
Abstract Objective Given the high discriminatory power of olfaction assessments in movement disorders, the current study sought to determine whether olfaction dysfunction differentially predicted cognitive decline in patients who have scans without evidence of dopaminergic deficit (SWEDD). Dopamine depletion is a major neuropathological feature of Parkinson’s disease (PD); however, 15% of patients with a clinical PD diagnosis have neuroimaging evidence of intact dopaminergic function. Recent work has suggested that patients with SWEDD are at a greater risk of cognitive impairment relative to those with PD. Methods Archival data were obtained from the Parkinson’s Progression Markers Initiative database. The total sample included three groups: PD (n = 401), SWEDD (n = 51), and HC (n = 175). Participants were categorized into non-impaired (-) or impaired (+) olfaction groups based on performance on the University of Pennsylvania Smell Identification Test, corrected for age and gender. Participants were administered the Montreal Cognitive Assessment twice and change scores were calculated to examine changes in cognition over time (baseline – two-year follow-up). Results A bootstrapped analysis of variance (ANOVA) revealed that the SWEDD+ group had lower MoCA scores than PD+ and HC+ groups at baseline (ps < .05). A bootstrapped ANOVA indicated that group differences were not significant at follow-up; rather, impaired baseline olfaction predicted cognitive decline across all study participants (p < .05), regardless of diagnosis. Conclusions Future studies are needed to assess whether the profile of motor and non-motor symptoms in SWEDD patients, including olfaction, is deserving of its own syndrome, or whether individual patients may fit better under alternative, existing diagnoses.