Loneliness in hoarding disorder: a systematic review and meta-analysis.

INTRODUCTION According to attachment theory, loneliness may be a cause of hoarding symptoms. However, due to mixed findings, it is unclear whether people with hoarding disorder (HD) are lonelier than healthy and clinical controls, whether there is a significant positive association between loneliness and hoarding, and whether loneliness causes more severe hoarding.

Method

We conducted a systematic review and included peer-reviewed quantitative cross-sectional, longitudinal, experimental and intervention research that measured hoarding and loneliness. We excluded hoarding due to other conditions and qualitative, review, and case study research. The final search was conducted on 16 May 2025 on PsycINFO, Medline, and Web of Science. We used the Quality Assessment with Diverse Studies to evaluate study quality and conducted a random effects meta-analysis to examine loneliness-hoarding correlations.

Results

Eleven papers with 13 studies (n = 2715) were included. Four studies compared loneliness in HD relative to controls. Ten studies examined the association between hoarding and loneliness. Only one experimental study examined the causal link. Results showed significantly higher loneliness in HD relative to healthy controls, but findings were mixed when compared with clinical controls. The meta-analysis showed a significant association between loneliness and hoarding, r = .38 [95% CI .33, .44].

Discussion

Our findings confirm that loneliness is a significant issue in HD. Due to its wide-ranging effects, we recommend that clinicians should assess and address loneliness in HD. Although we are confident that loneliness is positively associated with hoarding, further research is required to establish a causal link.