The relationship between meaning in life and apathy in people with Parkinson's disease: a cross-sectional analysis

Behavioral disorders in Parkinson disease: current view

Patients with Parkinson disease (PD) frequently experience several behavioral symptoms, such as anxiety, apathy, irritability, agitation, impulsive control and obsessive-compulsive or REM sleep behavior disorders, which can cause severe psychosocial problems and impair quality of life. Occurring in 30-70% of PD patients, these symptoms can manifest at early stages of the disease, sometimes even before the appearance of classic motor symptoms, while others can develop later. Behavioral changes in PD show distinct patterns of brain atrophy, dopaminergic and serotonergic deterioration, altered neuronal connectivity in frontostriatal, corticolimbic, default mode and other networks due to a cascade linking molecular pathologies and deficits in multiple behavior domains. The changes suggest a multi-system neurodegenerative process in the context of a specific α-synucleinopathy inducing a variety of biochemical and functional changes, the neurobiological basis and clinical relevance of which await further elucidation. This paper is intended to review the recent literature with focus on the main behavioral disturbances in PD patients, their epidemiology, clinical features, risk factors, animal models, neuroimaging findings, pathophysiological backgrounds, and treatment options of these deleterious lesions.

Meaning in life and Parkinson's disease in the UK Biobank

Introduction

Meaning in life is an aspect of eudaimonic well-being associated with lower dementia risk. This research examines whether this protective association extends to Parkinson's disease (PD).

Methods

Participants (N = 153,569) from the UK Biobank reported on their meaning in life. Cases of PD were identified through health records.

Results

Meaning in life was associated with a 50 % lower likelihood of prevalent PD (OR = 0.68, 95 % CI = 0.59-0.78). Over the 5-year follow-up, meaning was associated with a 35 % lower risk of incident PD (HR = 0.74, 95 % CI = 0.65-0.83), an association robust to sociodemographic characteristics, depression, history of seeking mental health care, smoking, physical activity, and genetic risk and not moderated by age, sex, education, deprivation, or genetic risk.

Conclusions

Meaning in life is associated with lower risk of incident PD, an association independent of other major risk factors and generalizable across sociodemographic groups. Meaning is a promising target of intervention for common neurodegenerative diseases.

Change in Purpose in Life Before and After Onset of Cognitive Impairment

Importance

Purpose in life is a critical aspect of psychological well-being that is associated with better cognitive outcomes across the continuum of dementia. To our knowledge, the natural history of purpose with onset of cognitive impairment has yet to be evaluated.

Objective

To evaluate changes in purpose in life prior to and after onset of cognitive impairment.

Design, Setting, and Participants

This cohort study used assessments of purpose in life and cognitive status from March 2006 to May 2021 in the Health and Retirement Study (HRS) and from May 2011 to November 2021 in the National Health and Aging Trends Study (NHATS).

Exposure

Cognitive impairment at each wave based on established thresholds in HRS and NHATS.

Main Outcomes and Measures

The main outcome was purpose in life, measured with the Ryff Measures of Psychological Well-Being in HRS and a validated item in NHATS.

Results

In HRS, 22 668 participants provided 50 985 assessments of purpose across all waves. In NHATS, 10 786 participants provided 53 880 assessments of purpose across all waves. In HRS, 58.3% of participants were female, with mean (SD) age of 64.76 (10.41) years at baseline; in NHATS, 57.4% were female, with mean (SD) age of 76.82 (7.71) years at baseline. Across waves, 6794 HRS participants (30%) and 4446 NHATS participants (41.2%) were in the cognitive impairment range. Accounting for demographic covariates and normative change in purpose, multilevel modeling indicated that standardized purpose in life declined significantly prior to onset of cognitive impairment (estimate for 10 years) in both HRS (b = -0.12; 95% CI, -0.17 to -0.07; P < .001) and NHATS (b = -0.10; 95% CI, -0.20 to -0.01; P = .03). Purpose declined significantly more rapidly following onset of cognitive impairment, with a standardized decline nearly 3 times larger compared with prior to impairment in HRS (b = -0.35; 95% CI, -0.41 to -0.29; P < .001) and 4 times larger in NHATS (b = -0.44; 95% CI, -0.53 to -0.34; P < .001).

Conclusions and Relevance

In this cohort study, purpose in life declined with emergence of cognitive impairment. The decline before onset was too small to be useful to detect impending impairment in clinical settings. The steeper decline following impairment suggests that individuals are aware that their purpose is declining. Purpose may be an intervention target following cognitive impairment to maintain well-being and to reduce or slow emergence of behavioral symptoms associated with low purpose.