Associations between Anticholinergic Burden and Skeletal Muscle Indices and Physical Function in Older Adults: A Scoping Review.

Background: Anticholinergic burden has been linked to adverse geriatric outcomes. However, quantitative evidence regarding its associations with skeletal muscle indices and functional outcomes remains limited, particularly for muscle quality. We conducted a scoping review to map the current evidence and identify research gaps. Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews, we searched PubMed, Google Scholar, and CiNii from inception to January 23, 2026 for English or Japanese primary observational or interventional studies that quantitatively assessed anticholinergic burden using validated or previously published scales/classifications and at least one outcome related to skeletal muscle (mass, quality, or strength), physical function, or activities of daily living (ADL)/instrumental ADL (IADL). Eligible populations were older adults (aged ≥60 years, or studies with a mean/median age ≥60 years, or studies reporting a predefined older-adult subgroup). Case reports, nonhuman studies, reviews, and editorials were excluded. Two reviewers independently screened records and charted data using a standardized form. Results: Of 231 identified records, 18 studies met the inclusion criteria. Two studies assessed skeletal muscle mass using bioelectrical impedance analysis, reporting appendicular skeletal muscle mass and skeletal muscle mass index; no study directly assessed skeletal muscle quality. Most studies evaluated physical function and/or ADL/IADL. The majority reported that higher anticholinergic burden was associated with poorer physical function and/or greater dependence in ADL/IADL, although some findings were subgroup-specific (e.g., restricted to older strata) or null for certain measures (e.g., grip strength and some Timed Up and Go analyses). Measures of anticholinergic burden and outcome ascertainment varied substantially across studies. Conclusions: Quantitative assessment of anticholinergic burden may serve as an auxiliary indicator to prompt medication review in older adults; however, the available evidence is associative and subject to residual confounding (including confounding by indication and polypharmacy). In contrast, evidence directly linking anticholinergic burden to skeletal muscle indices - especially muscle quality - remains scarce. Studies incorporating direct skeletal muscle assessments are needed to better characterize these associations and explore potential mechanisms, including indirect pathways involving the central nervous system, mood, and activity.