Prevalence of subthreshold depression among older adults with mild cognitive impairment: a systematic review and...

This systematic review and meta-analysis aimed to estimate the pooled prevalence of subthreshold depression (StD) among older adults with mild cognitive impairment (MCI). A comprehensive search of ten electronic databases was conducted up to March 27, 2025. Quality assessment was conducted using the Joanna Briggs Institute (JBI) tools, and publication bias was examined with funnel plots, Egger's test and trim-and-fill. Fifty-two studies involving 29,321 individuals were included. The pooled prevalence of StD among older adults with MCI was 28.1% (95% CI: 24.2%-32.0%, I² = 98.4 %, τ² = 0.019, p < 0.001). Exploratory subgroup analyses suggested that individuals aged 70-79 years (29.9%), studies with a higher male composition (>50% males, 33.7%), cohort designs (29.3%), hospital-based samples (36.2%), European regions (34.5%) and studies that ascertained StD without excluding MDD through clinical assessment (28.9%) reported higher prevalence. However, given the high heterogeneity within subgroups, these apparent differences should not be interpreted as definitive. Overall, StD appears relatively common among older adults with MCI under a broad operational definition, with prevalence varying by demographic and study characteristics. Early identification and appropriate management of StD within MCI care pathways are warranted to address symptom burden.