Gait speed is a good predictor of cognitive decline in later life. However, it is not known whether step length or step frequency is better for predicting such decline. This study aimed to compare the predictive value for cognitive decline of gait performance measures in a population of older Japanese. Among 853 cognitively intact adults aged 70 years or older who participated in a baseline survey, 666 (mean age, 75.5 [SD 4.4] years; women, 59.3%) were reevaluated at least once during the subsequent 4-year period. Cognition was assessed by Mini-Mental State Examination (MMSE), and cognitive decline was defined as a decrease of three points or more on the Mini-Mental State Examination during follow-up. During a median follow-up of 2.7 years, 110 adults (16.5%) had cognitive decline. Among the measures of gait performance (speed, step length, and frequency), step length was the most predictive of cognitive decline. After controlling for important confounders, older men in the lowest and middle tertiles of step length at maximum speed and older women in the lowest and middle tertiles of step length at usual speed were 4.42 (95% confidence interval: 1.65–11.8), 2.17 (0.82–5.71), 5.76 (2.15–15.4), and 2.44 (0.94–6.35) times as likely to develop cognitive decline, respectively, as those of the same sex and walking speed who were in the highest tertile. Step length was an independent predictor of cognitive decline in a general population of older adults and may be a better predictor than overall gait speed of such decline.

Micronutrients are associated with dementia and cognitive decline among older adults. However, nutritional biomarkers of such decline have not been identified. We attempted to identify nutritional biomarkers that were independent risk markers of cognitive decline in a population of older Japanese. Among 873 cognitively intact adults aged 70 years or older at baseline, 682 (mean age [standard deviation], 75.5 [4.4] years; women 59.7%) were followed for a period of up to 4 years, and nutritional biomarkers in a blood panel were assessed, namely, red blood cell count, hematocrit, mean corpuscular volume, hemoglobin, total cholesterol, high-density lipoprotein cholesterol, hemoglobin A1c, creatinine, albumin, blood glucose, γ-glutamyl transpeptidase, triglyceride, and white blood cell count. Cognition was assessed by the Mini-Mental State Examination, and cognitive decline was defined as a decrease of at least three points on the Mini-Mental State Examination. During an average follow-up of 2.7 years, 115 adults (16.9%) developed cognitive decline. After controlling for important confounders, the odds ratios for cognitive decline in the lowest and middle tertiles of red blood cell count were 2.62 (95% confidence interval: 1.44–4.74) and 2.18 (1.20–3.96), respectively, as compared with the highest tertile. The corresponding odds ratios were 1.81 (1.05–3.22) and 1.03 (0.58–1.83), respectively, for high-density lipoprotein cholesterol and 2.06 (1.14–3.77) and 1.02 (0.54–1.94) for albumin. Low red blood cell count, high-density lipoprotein cholesterol, and albumin were independent risk markers for subsequent cognitive decline in a general population of older adults and may be useful in early clinical screening.

Previous studies examined the physical characteristics of older dog owners. However, associations of health-related factors with dog/cat ownership have not been comprehensively evaluated. This cross-sectional study examined physical function, physical activity, social function, and psychological function of a population of community-dwelling older Japanese dog and cat owners after controlling for important confounders. The analysis included data from 11,233 community-dwelling adults aged 65 years or older (51.5% women; 52.3% aged 75–84), in Ota City, Tokyo, Japan. Pet ownership experience and pet species owned were determined by self-reported questionnaire, and current, past, and never dog/cat ownership was analyzed. Analysis of variables related to physical function and physical activity showed that motor fitness scale and walking activity were significantly associated with experience of dog ownership, after adjustment for important sociodemographic and health characteristics. Analysis of social function showed that interaction with neighbors, social isolation, and trust in neighbors were significantly associated with experience of dog ownership and cat ownership. As compared with respondents with no history of pet ownership, motor fitness and walking activity are greater for dog owners and social function is higher for dog and cat owners. Caring for a dog or cat might be an effective health promotion strategy to increase physical activity and facilitate social participation among older adults.