...plays a role in memory and Alzheimer's disease,34; said...
(1)细节理解题。根据第一段Our study found that gum (牙龈) disease and tooth loss were linked to brain shrinkage (萎缩) in the hippocampus,which plays a role in memory and Alzheimer's disease(我们的研究发现,牙龈疾病和牙齿脱落与海马体的大脑萎缩有关