Fatigue, which can be classified into physical and cognitive subtypes (Schiehser et al., 2012), is a common non-motor symptom in persons with Parkinson’s disease (PD) that has no clear treatment. Cognitive changes, also common in PD (Litvan et al., 2012), may impact how patients perceive fatigue (Kukla et al., 2021). Grit is a personality trait defined as perseverance and passion towards a long-term goal, and is associated with multiple positive outcomes such as lower fatigue levels in healthy individuals (Martinez-Moreno et al., 2021). However, scarce research has examined the relationship between grit and fatigue in persons with PD. Therefore, we aimed to investigate the relationship between fatigue (cognitive and physical) and grit, as well as the impact of cognitive status (i.e., cognitive normal vs. mild cognitive impairment [MCI]) on this relationship in non-demented individuals with PD.

Participants were 70 non-demented individuals with PD who were diagnosed as either cognitively normal (n=20) or MCI (n=50) based on Level II of the Movement Disorder Society PD-MCI criteria. Participants completed the Modified Fatigue Impact Scale (MFIS), which consists of two subscales (cognitive and physical fatigue) that are combined for a total overall fatigue score. Participants also completed the Grit Scale, which consists of items such as ambition, perseverance, and consistency. ANOVAs were conducted to determine differences in grit between PD-cognitively normal vs PD-MCI groups. Correlations and multiple hierarchical regressions controlling for significant demographics (i.e., age, education, sex), mood (i.e., depression, anxiety) and disease variables (i.e., disease duration, Levodopa equivalent dosage) with backwards elimination were conducted to evaluate the relationship between grit and fatigue (MFIS total score and MFIS cognitive and physical fatigue subscales).

There was no significant difference in grit total scores between PD patients who were cognitively normal or MCI (p = .336). Higher grit total scores predicted lower MFIS total (ß = -.290, p = .005) and lower cognitive fatigue (ß = -.336, p < .001) scores in the total sample, above and beyond relevant covariates as well as cognitive status. Grit scores were not significantly associated with physical fatigue (ß = -.206, p = .066). Furthermore, cognitive status was not a significant predictor of fatigue scores in any of the models (all p’s > .28).

Findings indicate that higher levels of grit are associated with lower levels of fatigue, specifically cognitive fatigue, in individuals with PD. These results held true for those who were cognitively normal or with MCI, suggesting that grit may impact fatigue in non-demented PD patients regardless of cognitive status. These findings underscore the importance of considering grit when assessing or treating fatigue, particularly cognitive fatigue, in persons with PD.