The sequence of physical and cognitive impairment and the association with mortality among unimpaired older mexican adults

Abstract

Background: Many older adults become physically and cognitively impaired. However, it is unclear whether unimpaired older adults are more likely to become physically or cognitively impaired first and if this sequence impacts mortality risk. Methods: Data came from the Mexican Health and Aging Study. The sample included 1,283 participants aged ≥60 years who were physically and cognitively unimpaired in 2001. Multinomial logistic regression was used to estimate probabilities of being unimpaired, cognitively impaired only, physically impaired only, or cognitively-physically impaired in 2003. Proportional hazard models were used to estimate mortality risk through 2015 according to physical and cognitive status in 2003. Results: The probabilities for being unimpaired, physically impaired only, cognitively impaired only, and cognitively-physically impaired in 2003 were 0.45, 0.22, 0.19, and 0.13, respectively. Older age, female sex, and arthritis were associated with significantly greater probability of becoming physically impaired only than cognitively impaired only in 2003. Cognitive impairment only (hazard ratio [HR] = 1.42, 95% confidence interval [CI] = 1.09–1.85) in 2003 but not physical impairment only (HR = 1.22, 95% CI = 0.94–1.58) was associated with greater mortality than being unimpaired in 2003. Cognitively-physically impaired participants had higher mortality risk than participants who were physically (HR = 1.58, 95% CI = 1.18–2.12) or cognitively (HR = 1.36, 95% CI = 1.01–1.84) impaired only. Discussion: The likelihood of becoming only physically or cognitively impaired over 2 years varies by demographic and health characteristics. The mortality risk for unimpaired older adults who become cognitively impaired only is similar to those who become physically impaired only. Research should determine if the sequence of cognitive and physical impairments is associated with other outcomes.