TY - JOUR
T1 - Apathy as a Within-Person Mediator of Depressive Symptoms and Cognition in Parkinson's Disease
T2 - Longitudinal Mediation Analyses
AU - Szymkowicz, Sarah M.
AU - Jones, Jacob D.
AU - Timblin, Holly
AU - Ryczek, Cameron A.
AU - Taylor, Warren D.
AU - May, Pamela E.
N1 - Publisher Copyright:
© 2021 American Association for Geriatric Psychiatry
PY - 2022/6
Y1 - 2022/6
N2 - Objective: Greater depressive symptoms are associated with worse cognitive functions in Parkinson's disease (PD); however, it is unclear what underlying factors drive this association. Apathy commonly develops in PD and may be a pathway through which depressive symptoms negatively influence cognition. Prior research examining depressive symptoms, apathy, and cognition in PD is limited by being predominantly cross-sectional. This study examined the role of apathy as a within- and between-person mediator for the longitudinal relationships between depression severity and cognitive functioning in patients with early PD. Methods: Participants included 487 individuals newly diagnosed with PD followed annually for up to 5 years by the Parkinson's Progression Marker Initiative. At each visit, participants completed depressive symptom measures, apathy ratings, and cognitive tests. Multi-level structural equation models examined both the within- and between-person effects of depressive symptoms on cognition through apathy, controlling for demographics and motor severity. Results: At the within-person level, apathy mediated the association between depressive symptoms and select cognitive functions (global cognition, attention/working memory, visuospatial functions, and immediate verbal memory; indirect effects, bootstrap p's <0.05). Significant between-person direct effects were found for depressive symptoms predicting apathy (boostrap p <0.001) and lower scores on most cognitive tests (bootstrap p's <0.05). However, the indirect effects did not reach significance, suggesting between-person mediation did not occur. Conclusion: Findings suggest worsening of depressive symptoms over time in patients with PD may be a risk factor for increased apathy and subsequent decline in specific cognitive functions.
AB - Objective: Greater depressive symptoms are associated with worse cognitive functions in Parkinson's disease (PD); however, it is unclear what underlying factors drive this association. Apathy commonly develops in PD and may be a pathway through which depressive symptoms negatively influence cognition. Prior research examining depressive symptoms, apathy, and cognition in PD is limited by being predominantly cross-sectional. This study examined the role of apathy as a within- and between-person mediator for the longitudinal relationships between depression severity and cognitive functioning in patients with early PD. Methods: Participants included 487 individuals newly diagnosed with PD followed annually for up to 5 years by the Parkinson's Progression Marker Initiative. At each visit, participants completed depressive symptom measures, apathy ratings, and cognitive tests. Multi-level structural equation models examined both the within- and between-person effects of depressive symptoms on cognition through apathy, controlling for demographics and motor severity. Results: At the within-person level, apathy mediated the association between depressive symptoms and select cognitive functions (global cognition, attention/working memory, visuospatial functions, and immediate verbal memory; indirect effects, bootstrap p's <0.05). Significant between-person direct effects were found for depressive symptoms predicting apathy (boostrap p <0.001) and lower scores on most cognitive tests (bootstrap p's <0.05). However, the indirect effects did not reach significance, suggesting between-person mediation did not occur. Conclusion: Findings suggest worsening of depressive symptoms over time in patients with PD may be a risk factor for increased apathy and subsequent decline in specific cognitive functions.
KW - Apathy
KW - Parkinson's disease
KW - cognitive functioning
KW - depression
KW - mediation
KW - structural equation modeling
UR - http://www.scopus.com/inward/record.url?scp=85121246059&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85121246059&partnerID=8YFLogxK
U2 - 10.1016/j.jagp.2021.11.007
DO - 10.1016/j.jagp.2021.11.007
M3 - Article
C2 - 34922823
AN - SCOPUS:85121246059
SN - 1064-7481
VL - 30
SP - 664
EP - 674
JO - American Journal of Geriatric Psychiatry
JF - American Journal of Geriatric Psychiatry
IS - 6
ER -