#Sarcopenia is independently associated with #parietal atrophy in older adults

Highlights
•Sarcopenia was common in old adults living in a retirement community (46.1%).

•Sarcopenia had moderate-severe global cortical, parietal and medial temporal atrophy.

•Sarcopenia is significantly associated with parietal atrophy in older adults.

•Age had a significant relationship with global cortical and medial temporal atrophy.

Abstract
Introduction
As populations age, sarcopenia becomes a major health problem among adults aged 65 years and older. However, little information is available about the relationship between sarcopenia and brain structure abnormalities. The objective of this study was to investigate associations between sarcopenia and brain atrophy in older adults and relationships with regional brain areas.

Methods
This prospective cohort study recruited 102 retirement community residents aged 65 years and older. All participants underwent gait speed measurement, handgrip strength measurement and muscle mass measurement by dual X-ray absorptiometry. Diagnosis of sarcopenia was made according to criteria of the Asian Working Group for Sarcopenia (AWGSOP). All patients underwent magnetic resonance imaging (MRI), and images were analysed for global cortical atrophy (GCA) (range 0–3), parietal atrophy (PA) (range 0–3) and medial temporal atrophy (MTA) (range 0–4).

Results
Among 102 older adult participants (81.4 ± 8.2 years), 47 (46.1%) were diagnosed with sarcopenia according to AWGSOP criteria. The sarcopenia group had more moderate to severe PA (Grade 2: 19.1% vs. 5.5%; grade 3:6.4% vs. 0%, P = 0.016) and GCA (Grade 2: 40.4% vs. 18.2%, P = 0.003) and a trend of more moderate to severe MTA (Grade 2: 46.8% vs. 30.9%; grade 3: 8.5% vs. 1.8%, P = 0.098) than the non-sarcopenia group. In univariate logistic regression, sarcopenia was significantly associated with PA (OR 5.94, 95% CI 1.56–22.60, P = 0.009), GCA (OR 3.05, 95% CI 1.24–7.51, P = 0.015), and MTA (OR 2.55, 95% CI 1.14–5.69, P = 0.023). In multivariable logistic regression analysis, sarcopenia was an independent risk factor for PA (adjusted OR 6.90, 95% CI 1.30–36.47, P = 0.023). After adjusting for all covariates, only age had a significant relationship with GCA (Adjusted OR 1.09, 95% CI 1.00–1.19, P = 0.044) and MTA (Adjusted OR 1.09, 95% CI 1.01–1.17, P = 0.022).

Conclusions
This is the first study to explore associations between sarcopenia and global as well as regional brain atrophy in older adults. The sarcopenia group had higher rates of moderate to severe PA, GCA and MTA than the non-sarcopenia group. PA was significantly associated with sarcopenia in older adults. Further longitudinal studies are needed to address the mechanism and pathogenesis of brain atrophy and sarcopenia.

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