Department of Psychiatry, The Icahn School of Medicine at Mount Sinai, New York, New York, USA.
Sheba Medical Center, The Joseph Sagol Neuroscience Center, Ramat Gan, Israel.
J Am Geriatr Soc. 2021 Jul;69(7):1826-1835. doi: 10.1111/jgs.17206. Epub 2021 May 5.
We examined whether sarcopenia is associated with the occurrence of late-life cognitive impairment.
Nondemented older adults (N = 1175) underwent annual testing with 17 cognitive tests summarized as a global cognitive score. A composite sarcopenia score was constructed based on muscle mass measured with bioelectrical impedance and muscle function based on grip strength. Cox proportional hazard models were employed to examine associations of sarcopenia with incident Alzheimer's dementia (AD) and incident mild cognitive impairment (MCI). Linear mixed-effect models determined the association of sarcopenia with cognitive decline. All models controlled for age, sex, education, race, and height squared.
Average follow-up was 5.6 years. More severe sarcopenia at baseline was associated with a higher risk of incident AD (hazard ratio [HR], 1.50 [95% confidence interval 1.20-1.86]; p < 0.001) and of MCI (1.21 [1.01-1.45]; 0.04) and a faster rate of cognitive decline (estimate = -0.013; p = 0.01). Analyses of the individual components of sarcopenia showed that muscle function was associated with incident AD, incident MCI, and cognitive decline with and without a term for lean muscle mass in the model. In contrast, lean muscle mass was not associated with incident cognitive impairment or cognitive decline when a term for muscle function was included in the model.
Poor muscle function, but not reduced lean muscle mass, drives the association of sarcopenia with late-life cognitive impairment. Further work is needed to identify features of muscle structure, which may increase the specificity of sarcopenia for identifying older adults at risk for late-life cognitive impairment.
我们研究了肌少症是否与老年认知障碍的发生有关。
无痴呆的老年人（N=1175）每年接受 17 项认知测试，汇总为一个总体认知评分。根据生物电阻抗法测量的肌肉量和握力反映的肌肉功能构建综合肌少症评分。采用 Cox 比例风险模型检验肌少症与阿尔茨海默病（AD）和轻度认知障碍（MCI）发病的相关性。线性混合效应模型确定肌少症与认知下降的相关性。所有模型均控制年龄、性别、教育、种族和身高平方。
平均随访时间为 5.6 年。基线时更严重的肌少症与 AD 发病风险较高相关（风险比 [HR]，1.50 [95%置信区间 1.20-1.86]；p<0.001）和 MCI（1.21 [1.01-1.45]；0.04）以及认知下降速度较快（估计值=-0.013；p=0.01）。肌少症各组成部分的分析表明，肌肉功能与 AD 发病、MCI 发病和认知下降相关，而不论模型中是否包含瘦肌肉质量项。相比之下，当模型中包含肌肉功能项时，瘦肌肉质量与认知障碍发病或认知下降无关。
肌肉功能差，但瘦肌肉质量不低，导致肌少症与老年认知障碍相关。需要进一步研究以确定肌肉结构的特征，这可能会提高肌少症识别老年认知障碍风险的特异性。
