Letter re: Trends in dementia prevalence, incidence, and survival rate in a Japanese community

I read with interest the article by Ohara et al.1 regarding trends in dementia prevalence, incidence, and survival rate in a Japanese community. The findings were similar to those reported in 2012 by Dodge et al.,2 in which Alzheimer disease (AD) rates for the elderly increased from 1% in 1985 to 7% in 2008. I explained that findings were due to the nutrition transition from the traditional Japanese diet to the Western diet, heavy in meat and other animal products, with a lag of 15–25 years.3 More recently, in a multicountry study, I found that dietary animal products other than milk were strongly correlated with AD prevalence 5–10 years prior to the prevalence data.4 The nutrition transition in Japan was also associated with the large increases in types of cancer common in Western countries, such as breast cancer, for which it was found that "the estimated time lag values for the influence of fat, animal protein, and TDF [total dietary fiber] were 20–32 years, 19–31 years, and 9–35 years, respectively."5 While increased survival plays an important role, it appears that the transition to the Western diet explains the bulk of increased AD rates in Japan. Owing to these concerns, the p values reported by the authors may provide an inaccurate picture of statistical significance. The data should be reanalyzed.
Source: Neurology - Category: Neurology Authors: Tags: WRITECLICK & amp;reg; EDITOR ' S CHOICE Source Type: research