Department of Oral Sciences, Sir John Walsh Research Institute, School of Dentistry, The University of Otago, Dunedin, New Zealand.
Department of Psychological Medicine, Dunedin School of Medicine, The University of Otago, Dunedin, New Zealand.
J Dent Res. 2021 Mar;100(3):226-231. doi: 10.1177/0022034520957233. Epub 2020 Sep 18.
Dementia is a major contributor to dependence and disability in older people, with aging societies characterized by growing numbers of people living with the condition. Dementia rates are highest in those with low education early in life, midlife hypertension, midlife hearing loss, depression, obesity, loneliness, a sedentary lifestyle, or sustained exposure to smoking or diabetes. Tooth loss is a putative risk factor for dementia which has received increasing research attention, but systematic review findings are mixed. Three main mechanisms have been proposed, involving 1) tooth loss leading to compromised nutrition and then leading to poorer central nervous system (CNS) function; 2) tooth loss resulting in fewer interocclusal contacts and so less somatosensory feedback to the CNS, leading to impaired cognition; and (3) chronic periodontitis resulting in tooth loss, but not before the inflammation has affected the CNS, impairing cognition. None of these is supported by compelling empirical evidence. Here, we use the life course approach to propose a plausible, empirically supported explanation for the associations between missing teeth and poorer cognitive function in older people. Evidence from longstanding cohort studies demonstrates that the putative association arises from cognitive function much earlier in life, in childhood. People with better childhood cognitive function have better oral health and access to routine dental care as they go through life, losing fewer teeth along the life course. They are also much more likely to have better cognitive function in old age. Their less cognitively able childhood counterparts will experience higher disease rates and poorer access to care, resulting in greater incremental tooth loss. Comparison of the 2 groups at any age from the mid-20s on will show greater numbers of missing teeth in the group who were less cognitively able in childhood. Those differences will be most pronounced in old age.
痴呆是老年人依赖和残疾的主要原因，随着社会老龄化，越来越多的人患有这种疾病。在那些早年受教育程度低、中年高血压、中年听力损失、抑郁、肥胖、孤独、久坐不动的生活方式或长期接触吸烟或糖尿病的人中，痴呆症的发病率最高。牙齿缺失是痴呆症的一个潜在危险因素，越来越受到研究关注，但系统评价结果喜忧参半。提出了三种主要机制，涉及 1）牙齿缺失导致营养受损，进而导致中枢神经系统 (CNS) 功能下降；2）牙齿缺失导致较少的咬合接触，从而减少对 CNS 的躯体感觉反馈，导致认知障碍；3）慢性牙周炎导致牙齿缺失，但炎症尚未影响 CNS 之前，导致认知障碍。没有一个机制得到令人信服的实证证据的支持。在这里，我们使用生命历程方法为老年人牙齿缺失与认知功能下降之间的关联提出一个合理的、有实证支持的解释。长期队列研究的证据表明，这种假定的关联源自生命早期的认知功能，即儿童时期。具有更好儿童认知功能的人在一生中具有更好的口腔健康和常规牙科护理的机会，因此在整个生命过程中牙齿脱落较少。他们在老年时也更有可能具有更好的认知功能。他们在儿童时期认知能力较差的同龄人将经历更高的疾病发病率和较差的护理机会，从而导致牙齿缺失增加。从 20 多岁中期开始，在任何年龄对这两组进行比较，都会发现认知能力较差的儿童组缺失的牙齿数量更多。这些差异在老年时最为明显。
