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. 2016 Jul 14;11(7):e0158720.
doi: 10.1371/journal.pone.0158720. eCollection 2016.

Cognitive Impairment and Disability in Older Japanese Adults

Hiroyuki Shimada  1 , Hyuma Makizako  1 , Takehiko Doi  1 , Kota Tsutsumimoto  1 , Sangyoon Lee  1 , Takao Suzuki  2   3
Affiliations

Cognitive Impairment and Disability in Older Japanese Adults

Hiroyuki Shimada et al. PLoS One. .

Abstract

The prevalence of disability is increasing due to an expanding aging population and an increasing incidence of chronic health problems. Cognitive impairment may predict the development of disability in older adults. Therefore, we examined the association of mild cognitive impairment (MCI) and/or general cognitive impairment (GCI, defined as a Mini Mental State Examination [MMSE] score of 20-23) with the development of disability in a cohort of Japanese community-dwelling older adults. A total of 4290 participants (aged ≥65 years) enrolled in the Obu Study of Health Promotion for the Elderly were classified according to the presence and degree of cognitive impairment as follows: cognitively healthy, GCI, MCI single domain (MCIs), MCIs with GCI, MCI multiple domain (MCIm), and MCIm with GCI. MMSE scores, risk factors for dementia, and incidences of new disability were recorded. After an average of 29.5 months, 205 participants (4.8%) experienced a new onset of disability. All subtypes of cognitive impairment showed significant relationships with disability except for GCI alone. The following hazard ratios (HRs) were determined: MCIs (HR, 2.04; 95% CI, 1.39-3.00), MCIs with GCI (HR, 2.10; 95% CI, 1.21-3.62), MCIm (HR, 2.32; 95% CI, 1.39-3.85), and MCIm with GCI (HR, 4.23; 95% CI, 2.73-6.57). These results indicate that cognitive impairment may be related to an increased risk for the development of disability. Healthcare providers should implement global cognitive assessments to identify MCI and GCI and consider preventive interventions for disability, especially in older persons.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Estimated survival rates according to the incidence of disability and cognitive impairment status.
The left panel shows survival curves according to the incidence of disability adjusted for age and sex, and the right panel shows the fully adjusted model. 1, non-cognitive impairment group; 2, non-mild cognitive impairment with general cognitive impairment group; 3, mild cognitive impairment single domain group; 4, mild cognitive impairment single domain with general cognitive impairment group; 5, mild cognitive impairment multiple domain group; 6, mild cognitive impairment multiple domain with general cognitive impairment group.
Fig 2
Fig 2. Hazard ratio estimates of relative disability risk in subgroups defined by sex, age, and depressive symptoms in stratified analyses.
See this image and copyright information in PMC

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