Objective: To investigate the impact of cognition and cognitive decline on quality of life (QoL) in an incident Parkinson’s disease (PD) cohort over three years.

Background: Cognitive impairment and dementia in PD (PDD) may be associated with poorer QoL. However, QoL is likely to change over time as PD progresses and patients may experience cognitive decline. Nevertheless, there is a paucity of studies investigating the longitudinal effects of PD and cognition on QoL.

Methods: Recently diagnosed patients with PD (n=212) completed a schedule of neuropsychological assessments, clinical history and the Parkinson’s disease Questionnaire (PDQ-39) to measure QoL as part of the ICICLE-PD study; these were repeated after 18 (n=190) and 36 months (n=158). Mild cognitive impairment (PD-MCI) was diagnosed using the International Parkinson and Movement Disorder Society criteria; 2 SD below normative data (age-sex matched healthy controls, n=99) was used as a cut off. Principal component analysis was used to reduce 10 neuropsychological tests to three cognitive factors: Attention, Memory/Executive function, and Global cognition.

Results: Participants with baseline PD-MCI reported greater decline in QoL over time compared to those with normal cognition (mean paired change 9.1±15.0 vs. 3.0±13.3, respectively, p<0.05). Regression analysis showed baseline PD-MCI was a small, but significant contributor to QoL at 36 months (β=0.2, p<0.01). For the minority (8%) who developed PDD, change in cognitive function had a much greater impact on QoL (β=10.3, p<0.05). Linear mixed effects modelling showed that brief cognitive tests, such as MoCA score, modestly predicted decline in QoL (β=-0.4, p<0.01); but attentional deficits had a stronger predictive power (β=-2.3, p<0.01).

Conclusions: PD-MCI was associated with poorer QoL at all points over three years. However, for individuals who developed PDD over follow-up, cognition had a much greater impact on QoL. Standard brief clinical tests, such as the MoCA, could predict to some degree patients at risk of declining QoL, but more sophisticated attentional tasks may have greater predictive power. Therefore, interventions to improve concentration and attention could potentially improve QoL.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/does-cognitive-decline-contribute-to-poorer-quality-of-life-in-incident-parkinsons-disease-a-three-year-follow-up/