Loneliness in Parkinson's disease: Subjective experience overshadows objective motor impairment

Loneliness is linked to poor life quality and health, but its relevance in Parkinson's disease (PD) is incompletely understood. The current study aimed to understand rates of loneliness and its determinants in PD.

Consecutive cross-sectional sampling resulted in 178 PD subjects (60 % men) across disease stages (86 % early-stage) with gold-standard diagnoses. Loneliness was characterized with two scales, PD was characterized by objective measures, motor ratings, and perceived functional impact, and social-emotional assessment included social connection, depression, and life space. Nonparametric bivariate and robust multivariate regression determined predictors of loneliness in PD, and social-emotional predictors of PD functional impact.

Most participants had concern, with 64.6 % endorsing high levels of loneliness. PD stage, but not motor impairment or other objective measures, predicted loneliness. In contrast, subjective measures of PD functional impact, social network size, social support, depression, and life space had a significant relationship with loneliness. In multivariate models, depression, PD functional impact, and social network size specifically emerged as the most important predictors of loneliness. Although social loneliness was generally more impacted by PD, men had more emotional loneliness. Similarly, loneliness was a potent, independent predictor of PD functional impact.

We show that loneliness is a critical issue in PD which relates more to individual response to disease than objective motor severity. Although PD most impacts general relationships' quality, men may have additional loss of intimate confidantes. Interventions targeting depression and social networks may not only improve loneliness but also improve PD functional impact.