Consumption of green tea, but not black tea or coffee, is associated with reduced risk of cognitive decline.

Our objective was to determine whether the consumption of green tea, coffee, or black tea influences the incidence of dementia and mild cognitive impairment (MCI) in older people. We conducted a population-based prospective study with Japanese residents aged >60 years from Nakajima, Japan (the Nakajima Project). Participants received an evaluation of cognitive function and blood tests. The consumption of green tea, coffee, and black tea was also evaluated at baseline. Of 723 participants with normal cognitive function at a baseline survey (2007-2008), 490 completed the follow up survey in 2011-2013. The incidence of dementia during the follow-up period (mean ± SD: 4.9 ± 0.9 years) was 5.3%, and that of MCI was 13.1%. The multiple-adjusted odds ratio for the incidence of overall cognitive decline (dementia or MCI) was 0.32 (95% CI: 0.16-0.64) among individuals who consumed green tea every day and 0.47 (95% CI: 0.25-0.86) among those who consumed green tea 1-6 days per week compared with individuals who did not consume green tea at all. The multiple-adjusted odds ratio for the incidence of dementia was 0.26 (95% CI: 0.06-1.06) among individuals who consumed green tea every day compared with those who did not consume green tea at all. No association was found between coffee or black tea consumption and the incidence of dementia or MCI. Our results indicate that green tea consumption is significantly associated with reduced risk of cognitive decline, even after adjustment for possible confounding factors.

Differences in the prevalence of dementia and mild cognitive impairment and cognitive functions between early and delayed responders in a community-based study of the elderly.

Significant differences exist in demographic characteristics between responders and non-responders in population-based studies on mental health and cognitive status, but much less is known regarding differences in the prevalence of dementia and cognitive dysfunction between them. Here we compared the prevalence of dementia and mild cognitive impairment between early responders of a mass brain function examination and delayed responders (non-responders of the mass brain function examination) in a survey of elderly Japanese citizens (≥65 years) to evaluate non-responder bias. All residents in an area of Nakajima, Japan, were considered as potential candidates (n = 783). Participants of a mass brain function examination were considered as "early responders." The cognitive functions of delayed responders were assessed by home visits. To assess the correlation between sociodemographic characteristics and cognitive functions, the early and delayed responders completed the same questionnaires and neuropsychological tests. Delayed responders (n = 320) were significantly older and less educated than the early responders (n = 307). The delayed responders also exhibited a higher frequency of dementia and mild cognitive impairment than the early responders, even when the groups were restricted to the age group 65-89 years. Our results suggest that population-based studies likely underestimate the prevalence of dementia and mild cognitive impairment, especially if the participation rate is low.

Effect of cognitive and aerobic training intervention on older adults with mild or no cognitive impairment: a derivative study of the nakajima project.

BACKGROUND: An increasing elderly population in Japan requires effective cognitive intervention programs for dementia. This study demonstrates the effectiveness of such programs for older adults. METHODS: The participants were local community-dwelling non-demented older adults and adults with mild cognitive impairment who underwent executive function and group aerobic training. In addition, a non-intervention group participated in activity sessions involving handicraft, Skutt ball matches, and cooking. The four criteria for assessment were cognitive function, instrumental activities of daily living, human relationships, and physical function. RESULTS: The participants in both intervention groups showed a significant improvement in their memory function compared with the non-intervention group. CONCLUSION: Early rehabilitation intervention using executive function and aerobic training programs may improve memory.