翻译：非常多的研究探索了这三个指数和疾病的关系。还有很多研究正在探索PDI和认知功能、老龄化的关系但还没有得出一致的结论还需要更多纵向研究的证实

Translation: A great deal of research has explored the relationship between these three indices and diseases. There are also numerous studies currently investigating the relationship between PDI and cognitive function, as well as aging, but consistent conclusions have not yet been reached, and further longitudinal studies are needed for confirmation.