一项刊登于国际杂志Neurology上的研究论文中，来自美国芝加哥拉什大学医学中心（Rush University Medical Center）的科学家通过研究指出，将要患痴呆症的个体或许会在疾病开始前的2-3年里开始出现记忆问题，该研究发现，多种痴呆症相关的大脑改变或病理学变化都和记忆意识的降低直接相关。
研究者Robert S. Wilson博士指出，我们研究发现，个体出现无意识的记忆问题或许是后期老年痴呆的前期征兆，这往往是由大脑中痴呆症相关的改变所引起的；记忆的无意识缺失在痴呆症中非常常见，但我们却并不清楚这到底是如何发生的，大量关于痴呆症的记忆无意识研究都主要集中于对已经诊断的患者来进行研究，而本文研究中研究者对一些还未出现痴呆症症状的老年个体进行研究。
文章中，研究者对2092名老年个体参与者进行了超过10年的跟踪研究调查，在研究初期，参与者平均年龄76岁，而且没有任何记忆或认知损伤的问题，参与者每年都会进行记忆和思考能力的测试，而且会被询问出现记忆困难的频率，以及相比10年前个体记忆的对比情况。
在研究中有239名个体被诊断为痴呆症，在参与者出现早期痴呆症之前，他们的记忆意识会比较稳定，但接下来平均每2.6年参与者的记忆就会出现大幅下降的趋势；尽管无意识记忆开始出现并且发展迅速在个体间存在差异，但事实上每个人都会在疾病发展的某个时候出现无意识的记忆缺失现象。
让研究者不可思议的是，相比老年个体而言，年轻个体出现记忆无意识的情况开始地较早，这或许是因为老年个体更希望自己在一个老化的年纪变得失忆；随后研究者对在研究过程中死亡的385名参与者的大脑进行研究，评估了这些参与者7种和痴呆症相关的大脑改变，结果发现，三种痴呆症相关的病理表现都和记忆无意识的快速下降直接相关，包括tau蛋白、脑梗死、大脑区域改变、TDP-43蛋白改变等。
随着个体大脑改变的开始，受影响的人们就会随着记忆的下降开始出现意识缺失的现象。最后研究者Wilson表示，本文研究强调了家庭成员的重要性，因为其可以及时寻找医生的帮助，同时医生也可以通过患者的朋友和家人来了解一些信息确定该名个体是否患有痴呆症，当然本文研究对于进行痴呆症的诊断或开发新型疗法也提供了新的线索。
doi:10.1212/WNL.0000000000001935
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Temporal course and pathologic basis of unawareness of memory loss in dementia
Robert S. Wilson, PhD, Patricia A. Boyle, PhD, Lei Yu, PhD, Lisa L. Barnes, PhD, Joel Sytsma, BA, Aron S. Buchman, MD, David A. Bennett, MD and Julie A. Schneider, MD
Objective: To characterize the natural history and neuropathologic basis of unawareness of memory loss in late-life dementia. Methods: Analyses are based on 2,092 older persons from 3 longitudinal clinical-pathologic cohort studies who had no memory or cognitive impairment at baseline. Annual evaluations included clinical classification of dementia plus self-rating and performance testing of memory. At death, there was a uniform neuropathologic examination to quantify 7 dementia-related pathologies. Results: In the full group, memory ratings were modestly correlated with memory performance (intercepts r = 0.26, p < 0.001; slopes r = 0.23, p < 001) and so we regressed each person's memory performance on their memory ratings, and the residuals provided longitudinal indicators of memory awareness. In a subset of 239 persons who developed dementia, episodic memory awareness was stable until a mean of 2.6 years before dementia onset (95% credible interval −2.7, –1.6); thereafter, memory awareness declined rapidly (mean annual change −0.32, 95% credible interval –0.37, –0.28). Older age at baseline was associated with later onset of memory unawareness. In a subset of 385 persons who died and underwent neuropathologic examination, transactive response DNA-binding protein 43 (TDP-43) pathology, tau tangles, and gross cerebral infarcts were related to decline in memory awareness. In the absence of these pathologies, no decline in memory awareness was evident. Results were similar in subgroups with and without dementia. Conclusions: Awareness of memory impairment typically begins to decline about 2–3 years before dementia onset and is associated with postmortem evidence of TDP-43 pathology, tangles, and gross cerebral infarcts.