Abstract
Between 2015 and 2030, the number of people living with dementia is forecast to increase from 500 million to 700 million in Japan. In the world, the increase by 2050 is estimated to be twofold in high income countries and more than threefold in low/middle income countries. Dementia has a huge economic impact. The total estimated worldwide cost of dementia will become US$ a trillion by 2018 and two trillion by 2030. There is evidence that multi-domain intervention (diet, exercise, cognitive training, vascular risk monitoring) may improve or maintain cognitive functioning in at-risk elderly people, but the effect size is not large. Thus, development of the disease modifying therapy (DMT) that can arrest the pathological process of Alzheimer’s disease (AD), the cause of more than a half of dementia subjects, has emerged as one of the highest priority issues in the world. Two major neuropathological hallmarks of AD, the amyloid b-protein (Ab) and tau protein deposits, are the targets for the development of both DMT and AD-specific biomarkers. Recent progress in the AD biomarker studies indicates that AD lesions appear 20 to 30 years prior to the occurrence of dementia and reach an advanced stage at the onset of dementia. Thus, to obtain significant effect, the intervention by DMT may need to be started before the clinical onset of AD. Then, clinical trials to develop DMT against AD have faced a number of barriers: high cost and long time to screen for appropriate subjects because of the low incidence of preclinical/prodromal AD cases in the non-demented aged population, and years-long trial periods to obtain the reliable results. Nevertheless, we must overcome such difficulties, presumably, by establishing the international collaborative effort and the public-private-partnership.
