Prospective Association of Handgrip Strength with Risk of New-Onset Cognitive Dysfunction in Korean Adults: A 6-Year National Cohort Study

Abstract

Dementia is one of the priority public health problems in the older population, and the number of people with dementia is steadily increasing. The longitudinal association of muscle strength with risk of new-onset cognitive dysfunction in a general population including middle and older adults remains unknown. The purpose of this study was to investigate the effects of low muscle strength on risk for new-onset cognitive dysfunction over 6 years using a large nationwide sample of cognitively healthy adults. Study participants included 6,435 middle and older adults (33,554 person-years of follow-up), using data from the Korean Longitudinal Study of Ageing 2006-2012. Muscular strength was measured using the maximum handgrip strength of each participant as an index of muscle quality. Low muscle strength was defined as one standard deviation below the mean using the handgrip strength index based on the study population. Cognitive function was evaluated using the Mini-Mental Status Evaluation. The hazard ratio (HR) for cognitive dysfunction significantly and linearly increased according to muscle strength status independent of potential confounding factors (HR: 1.36, 95% confidence interval [CI]: 1.18-1.56 for low vs. normal-high group). Using stratified analyses, a significant association between muscle strength status and risk of cognitive impairment was observed in those with low physical activity, but not those with high physical activity. We show that handgrip strength is associated with increased risk of new-onset cognitive dysfunction over 6 years of follow-up in cognitively healthy middle aged and older adults at baseline.

The association between health‐related factors, physical and mental diseases, social activities, and cognitive function in elderly Koreans: a population‐based cross‐sectional study

“…Few studies have examined the relationship between hand grip strength and cognitive function. 37 Furthermore, the present study verified the association between hand grip strength and cognitive function while adjusting other measures of physical function, specifically ADL and IADL. 58 Attendance and participation in social activities were closely associated with cognitive function.…”

“…hand grip, toe grip, gait) support this argument. [37][38][39] Sociodemographic variables, such as age, education, and marital status, have been found to be significant predictors of cognitive decline in previous studies. In particular, age was a powerful predictor of cognitive impairment.…”

“…7,35 Interestingly, some researchers have argued that hand grip strength is a preventive factor of cognitive decline. [36][37][38] The similarities in the brain areas and networks involved in cognition and muscle strength (e.g. hand grip, toe grip, gait) support this argument.…”

Declines in grip strength may indicate early changes in cognition in healthy middle-aged adults

“…The purpose of this exploratory study was to investigate the relationship between grip strength and cognitive function in young and middle-aged adults. Although previous studies have examined the relationship between grip strength and global cognition for participants 65 years or older, [2,3,9,[11][12][13][14] very few studies [22,23] have examined such relationships in younger and middle-aged adults or examined specific domains of cognition. Our results indicate that middle-aged adults demonstrate significantly weaker grip strength compared to young adults.…”

<p>Grip Strength: An Indispensable Biomarker For Older Adults</p>

“…The studies include Japanese, Korean, and Italian populations, follow-up periods of 1 to 10 years, and cognitive tests as diverse as the Mini-Mental State Evaluation, Digit Symbol Substitution Test, Clock Drawing Test, and the Clinical Dementia Rating Scale. [119][120][121][122][123] The final predictive value of grip strength addressed herein is that relative to hospitalization. Simmonds et al examined the association between grip strength and the combined rate of hospital admission/death over the following 10 years.…”