Awareness in severe Alzheimer’s disease: a systematic review

Abstract

Objective: There is limited understanding about how people in the severe stages of Alzheimer's disease (AD) experience and demonstrate awareness. We synthesised all available evidence with the aim of understanding how awareness is preserved or impaired in severe AD and what evidence there is for different levels of awareness according to the levels of awareness framework. Method: A systematic search of the following databases: Embase, PsycINFO, MEDLINE and Web of Science was carried out. A narrative synthesis and analysis was conducted of all included studies. All studies were assessed for quality using the AXIS and CASP tools. Results: Our findings suggest that lower level sensory awareness is relatively maintained in severe AD. Findings for higher level awareness are variable and this may be related to the diversity of methods that have been used to explore awareness in these circumstances. Conclusion: Awareness is complex, heterogeneous and varies significantly between individuals. Environmental and contextual factors have a significant impact on whether awareness is observed in people with severe AD. Adaptation of the environment has the potential to facilitate the expression of awareness while education of caregivers may increase understanding of people with severe AD and potentially improve the quality of care that is received.

Awareness of Cognitive Decline in Patients With Alzheimer's Disease: A Systematic Review and Meta-Analysis

“…Indeed, the widespread brain damage occurring in the advanced stages of AD compromises the information transfer and the anterograde memory, among other functions. Generally, this results in the patients having a very altered perception of their current experience, reduced awareness of what is happening in their surroundings, and to their state of health (O'Shaughnessy et al, 2021 ). At the late stage of the disease, the degradation is so massive that it affects not only the awareness of being ill but also the self-knowledge and sense of identity (Addis and Tippett, 2004 ).…”

Understanding Alzheimer's disease as a disorder of consciousness

“… 9 Studies generally suggest that awareness at this level becomes increasingly impaired with progression of AD; however, some individuals with severe AD may still show some limited awareness of their cognitive decline. 9 , 10 , 11 , 12 , 13 Anosognosia is related to other overlapping features of higher‐level awareness and cognitive function affected by AD, and to the integration of these processes (see Box 2 ). A component of higher‐level awareness associated with episodic memory is autonoetic consciousness.…”

“…While there is variability in higher‐level social awareness in early AD, this appears to decline as dementia progresses into the moderate–severe stages, 34 , 48 although inferences made from observations suggest some people with severe AD may retain some ability to empathize with others. 13 …”

High‐frequency transcranial magnetic stimulation protects APP/PS1 mice against Alzheimer’s disease progress by reducing APOE and enhancing autophagy

“…Alzheimer's disease (AD) is a progressive neurodegenerative disease that seriously endangers the health of middle‐aged and elderly people. With the aging of the population, the number of people suffering from AD is increasing rapidly, which is estimated to increase three times by 2050, and brings heavy burden to families and societies (Frankel et al., 2019; O'Shaughnessy et al., 2020). The characteristic pathological signs of AD are senile plaques formed by β‐amyloid (Aβ) deposition and neurofibrillary tangles formed by tau protein hyperphosphorylation, as well as neuron loss accompanied by glial cell proliferation.…”