Weakness Thresholds Are Differentially Linked to Cognitive Function by Obesity Status in Older Americans

Joshua Batesole; Grant R Tomkinson; Kirk I Erickson; Donald Jurivich; Justin J Lang; Brenda M McGrath; Sheria G Robinson-Lane; Ashleigh E Smith; Ryan McGrath

doi:10.3233/ADR-230190

Weakness Thresholds Are Differentially Linked to Cognitive Function by Obesity Status in Older Americans

J Alzheimers Dis Rep. 2024 Apr 8;8(1):601-608. doi: 10.3233/ADR-230190. eCollection 2024.

Authors

Joshua Batesole^{1

2}, Grant R Tomkinson³, Kirk I Erickson^{4

5}, Donald Jurivich⁶, Justin J Lang^{3

7

8}, Brenda M McGrath⁹, Sheria G Robinson-Lane¹⁰, Ashleigh E Smith³, Ryan McGrath^{1

2

3

6

11}

Affiliations

¹ Healthy Aging North Dakota, North Dakota State University, Fargo, ND, USA.
² Department of Health, Nutrition, and Exercise Sciences, North Dakota State University, Fargo, ND, USA.
³ Alliance for Research in Exercise, Nutrition and Activity (ARENA), Allied Health and Human Performance, University of South Australia, Adelaide, Australia.
⁴ Neuroscience, AdventHealth Research Institute, Orlando, FL, USA.
⁵ Department of Psychology, University of Pittsburgh, Pittsburgh, PA, USA.
⁶ Department of Geriatrics, University of North Dakota, Grand Forks, ND, USA.
⁷ Centre for Surveillance and Applied Research, Public Health Agency of Canada, Ottawa, ON, Canada.
⁸ School of Epidemiology and Public Health, University of Ottawa, Ottawa, ON, Canada.
⁹ OCHIN Inc., Portland, OR, USA.
¹⁰ School of Nursing, University of Michigan, Ann Arbor, MI, USA.
¹¹ Fargo VA Healthcare System, Fargo, ND, USA.

Abstract

Background: Weakness can be operationalized with several thresholds, which in turn, could impact associations with cognitive impairment when considering obesity status.

Objective: We examined the associations of absolute, normalized, and collective weakness thresholds on future cognitive impairment by obesity status in older adults.

Methods: We performed a secondary data analysis on the 2006-2018 waves of the Health and Retirement Study. A spring-type dynamometer collected handgrip strength (HGS). Males were categorized weak if their HGS was <35.5-kg (absolute), <0.45-kg/kg (body mass normalized), or <1.05-kg/kg/m² (body mass index (BMI) normalized), while females were defined as weak if their HGS was <20.0-kg, <0.337-kg/kg, or <0.79-kg/kg/m². The modified Telephone Interview of Cognitive Status examined cognitive function. Persons scoring ≤10 had a cognitive impairment. Obesity was categorized as BMI ≥30 kg/m².

Results: We included 7,532 and 3,584 persons aged ≥65-years living without and with obesity, respectively. Those without obesity but beneath the absolute weakness threshold had 1.54 (95% confidence interval (CI): 1.24-1.91) greater odds for future cognitive impairment. Persons with obesity and beneath each threshold also had greater odds for future cognitive impairment: 1.89 (95% CI: 1.28-2.78) for absolute, 2.17 (95% CI: 1.02-4.62) for body mass normalized, and 1.75 (95% CI: 1.10-2.80) for BMI normalized. Older Americans without obesity but underneath all the weakness thresholds had 1.32 (95% CI: 1.00-1.74) greater odds for impairment in cognitive function, while persons with obesity had 2.76 (95% CI: 1.29-5.93) greater odds.

Conclusions: There should be consideration for how body size and different weakness thresholds may influence future cognitive outcomes.

Keywords: Aging; Alzheimer’s disease; body composition; body mass index; cognition; dementia; functional status; geriatrics; muscle strength; muscle strength dynamometer.