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Mediation of Cognitive Function Improvements by Strength Gains After Resistance Training in Older Adults with Mild Cognitive Impairment: Outcomes of the Study of Mental and Resistance Training
Author(s) -
Mavros Yorgi,
Gates Nicola,
Wilson Guy C.,
Jain Nidhi,
Meiklejohn Jacinda,
Brodaty Henry,
Wen Wei,
Singh Nalin,
Baune Bernhard T.,
Suo Chao,
Baker Michael K.,
Foroughi Nasim,
Wang Yi,
Sachdev Perminder S.,
Valenzuela Michael,
Fiatarone Singh Maria A.
Publication year - 2017
Publication title -
journal of the american geriatrics society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.992
H-Index - 232
eISSN - 1532-5415
pISSN - 0002-8614
DOI - 10.1111/jgs.14542
Subject(s) - medicine , confidence interval , randomized controlled trial , physical therapy , effects of sleep deprivation on cognitive performance , cognition , psychiatry
Objectives To determine whether improvements in aerobic capacity ( VO 2peak ) and strength after progressive resistance training ( PRT ) mediate improvements in cognitive function. Design Randomized, double‐blind, double‐sham, controlled trial. Setting University research facility. Participants Community‐dwelling older adults (aged ≥55) with mild cognitive impairment ( MCI ) (N = 100). Intervention PRT and cognitive training (CT), 2 to 3 days per week for 6 months. Measurements Alzheimer's Disease Assessment Scale–cognitive subscale ( ADAS ‐Cog); global, executive, and memory domains; peak strength (1 repetition maximum); and VO 2peak . Results PRT increased upper (standardized mean difference ( SMD ) = 0.69, 95% confidence interval = 0.47, 0.91), lower ( SMD = 0.94, 95% CI = 0.69–1.20) and whole‐body ( SMD = 0.84, 95% CI = 0.62–1.05) strength and percentage change in VO 2peak (8.0%, 95% CI = 2.2–13.8) significantly more than sham exercise. Higher strength scores, but not greater VO 2peak , were significantly associated with improvements in cognition ( P < .05). Greater lower body strength significantly mediated the effect of PRT on ADAS ‐Cog improvements (indirect effect: β = −0.64, 95% CI = −1.38 to −0.004; direct effect: β = −0.37, 95% CI = −1.51–0.78) and global domain (indirect effect: β = 0.12, 95% CI = 0.02–0.22; direct effect: β = −0.003, 95% CI = −0.17–0.16) but not for executive domain (indirect effect: β = 0.11, 95% CI = −0.04–0.26; direct effect: β = 0.03, 95% CI = −0.17–0.23). Conclusion High‐intensity PRT results in significant improvements in cognitive function, muscle strength, and aerobic capacity in older adults with MCI . Strength gains, but not aerobic capacity changes, mediate the cognitive benefits of PRT . Future investigations are warranted to determine the physiological mechanisms linking strength gains and cognitive benefits.