Angiotensin-Converting Enzyme Insertion/Deletion Polymorphism, Lower Extremity Strength, and Physical Performance in Older Adults

ACE I/D genotype associates with strength in sarcopenic men but not with response to ACE inhibitor therapy in older adults with sarcopenia: Results from the LACE trial

BACKGROUND

Angiotensin II (AII), has been suggested to promote muscle loss. Reducing AII synthesis, by inhibiting angiotensin converting enzyme (ACE) activity has been proposed as a method to inhibit muscle loss. The LACE clinical trial was designed to determine whether ACE inhibition would reduce further muscle loss in individuals with sarcopenia but suffered from low recruitment and returned a negative result. Polymorphic variation in the ACE promoter (I/D alleles) has been associated with differences in ACE activity and muscle physiology in a range of clinical conditions. This aim of this analysis was to determine whether I/D polymorphic variation is associated with muscle mass, strength, in sarcopenia or contributed to the lack of response to treatment in the LACE study.

METHODS

Sarcopenic individuals were recruited into a 2x2 factorial multicentre double-blind study of the effects of perindopril and/or leucine versus placebo on physical performance and muscle mass. DNA extracted from blood samples (n = 130 72 women and 58 men) was genotyped by PCR for the ACE I/D polymorphism. Genotypes were then compared with body composition measured by DXA, hand grip and quadriceps strength before and after 12 months' treatment with leucine and/or perindopril in a cross-sectional analysis of the influence of genotype on these variables.

RESULTS

Allele frequencies for the normal UK population were extracted from 13 previous studies (I = 0.473, D = 0.527). In the LACE cohort the D allele was over-represented (I = 0.412, D = 0.588, p = 0.046). This over-representation was present in men (I = 0.353, D = 0.647, p = 0.010) but not women (I = 0.458, D = 0.532, p = 0.708). In men but not women, individuals with the I allele had greater leg strength (II/ID = 18.00 kg (14.50, 21.60) vs DD = 13.20 kg (10.50, 15.90), p = 0.028). Over the 12 months individuals with the DD genotype increased in quadriceps strength but those with the II or ID genotype did not. Perindopril did not increase muscle strength or mass in any polymorphism group relative to placebo.

CONCLUSION

Our results suggest that although ACE genotype was not associated with response to ACE inhibitor therapy in the LACE trial population, sarcopenic men with the ACE DD genotype may be weaker than those with the ACE I/D or II genotype.

Associations of Usual and Fast Gait Speed With Physical Performance and Balance Confidence in Community-Dwelling Older Adults: Implications for Assessment

BACKGROUND AND PURPOSE

Gait speed is a robust measure that offers many advantages clinically. However, decisions concerning its utilization exist, including whether to assess usual or fast gait speed. The current study aimed to identify whether usual or fast gait speed was more strongly associated with physical performance measures and balance confidence. A secondary aim was to explore these relationships within subgroups based on fall risk status.

METHODS

This was an observational study with a cross-sectional design involving 57 community-dwelling older adults (77.2% female; mean age = 68.8, SD = 6.5 years, range = 60-87 years) who were assessed on the following variables: usual and fast gait speed, knee extension strength, step execution time, 6-minute walk test (6MWT), and Activities-specific Balance Confidence Scale (ABC-6). Spearman ρ correlations were computed to determine bivariate associations of usual and fast gait speed with physical performance measures and balance confidence for the whole sample and within subgroups based on fall risk [lower fall risk (n = 28) vs higher fall risk (n = 29)]. Multiple linear regression models were estimated with either usual or fast gait speed as key predictors of knee extension strength, step execution time, 6MWT, and ABC-6.

RESULTS AND DISCUSSION

Stronger correlations were observed for fast gait speed compared with usual gait speed with all physical performance measures and balance confidence for the entire sample and within the higher fall risk group. Multiple regression results indicated that models with fast rather than usual gait speed as the key predictor explained more of the variance in 6MWT (R2 = 64.5% vs 45.6%), ABC-6 (R2 = 28.5% vs 25.4%), step execution time (R2 = 24.9% vs 19.0%), and knee extension strength (R2 = 15.7% vs 7.2%).

CONCLUSIONS

Fast gait speed showed stronger associations and better predictive capabilities compared with usual gait speed with physical performance measures and balance confidence in older adults. Despite being measured less often than usual gait speed, fast gait speed assessment warrants additional consideration.

The angiotensin-converting enzyme gene insertion/deletion polymorphism interacts with fear of falling in relation to stepping speed in community-dwelling older adults

BACKGROUND

Despite the association of genetic factors with falls, balance, and lower extremity functioning, interaction of the angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism with fear of falling (FOF) in relation to stepping performance has, to the best of our knowledge, not been investigated in older adults.

OBJECTIVE

The purpose of this study was to examine the interaction effects of the ACE I/D polymorphism with FOF in relation to stepping performance in older adults.

METHODS

Eighty-eight community-dwelling adults 60 years or older participated in a cross-sectional observational study. Participants completed tests of rapid and distance stepping, and self-reported FOF (yes/no). Participants provided saliva for ACE genotyping. General linear models evaluated ACE genotype × FOF interaction effects in relation to stepping performance. The α level was set at 0.05.

RESULTS

The ACE I/D polymorphism exhibited significant interaction effects (p for interactions 0.002 ≤ p ≤ .04) with FOF in relation to stepping speed. Relationships between FOF and stepping speed varied among ACE genotypes. The insertion/insertion (II) genotype was significantly associated (p = .01) with slow stepping in individuals with, but not without FOF (p > .05).

CONCLUSION

Variation in relationships between FOF and stepping speed among ACE genotypes suggests a role for the ACE I/D polymorphism in modifying relationships between FOF and stepping speed in older adults. The association of the ACE II genotype with slow stepping performance in individuals with, but not without FOF, suggests that older adults with the ACE II genotype and FOF may be at increased risk for poor stepping performance and associated functional declines.