Neural Correlates of Anosognosia in Dementia: A Systematic Review and Meta-analysis
Abstract
Dementia is a condition in which a person experiences a decline in cognitive abilities, including remembering and reasoning, which can interfere with their ability to perform daily activities. It is a general term that covers a variety of diseases including Alzheimer’s disease (AD), Frontotemporal dementia, Lewy body dementia, Vascular dementia, etc. Anosognosia, characterized by the lack of awareness of one's own cognitive deficits, is a prominent feature of many neurodegenerative diseases, such as Alzheimer's disease and frontotemporal dementia.
Magnetic Resonance Imaging (MRI) studies have been used to investigate the neural correlates of awareness impairment in various neurodegenerative diseases [1]. Several studies have shown that anosognosia in AD and behavioral variant frontotemporal dementia (bvFTD) is associated with structural changes in the prefrontal cortex, posterior cingulate cortex, and hippocampus, as well as decreased activation in the prefrontal cortex and increased activation in the default mode network [2], [3]. These findings suggest that awareness impairment in different neurodegenerative diseases is associated with specific structural and functional changes in distinct brain regions [1]. This knowledge is important for developing targeted interventions to improve awareness in patients with neurodegenerative diseases. Nonetheless, more research is needed to fully comprehend the underlying neural mechanisms.
The aim of this study is, first, to systematically review studies on the association between anosognosia and measures of brain structure or function using MRI scans, in different neurodegenerative diseases. A comprehensive search of a major database, PubMed, will be conducted to identify relevant studies. Based on exclusion and inclusion criteria, data on study and participant characteristics, anosognosia measures, and brain imaging measures will be extracted. Later, depending on the findings, an activation likelihood estimation (ALE) meta-analysis will be conducted. The primary objective of the analysis is to investigate the correlation between anosognosia and measures of brain structure or function, while secondary outcomes will include the effect of disease type, disease severity, and cognitive domain on the observed associations.
References
[1] M. Leocadi, E. Canu, A. Paldino, F. Agosta, and M. Filippi, “Awareness impairment in alzheimer’s disease and frontotemporal dementia: A systematic MRI Review,” Journal of Neurology, vol. 270, no. 4, pp. 1880–1907, 2022. doi:10.1007/s00415-022-11518-9
[2] M. Amanzio et al., “Unawareness of deficits in alzheimer’s disease: Role of the Cingulate Cortex,” Brain, vol. 134, no. 4, pp. 1061–1076, 2011. doi:10.1093/brain/awr020
[3] S. Shinagawa et al., “Neural basis of motivational approach and withdrawal behaviors in neurodegenerative disease,” Brain and Behavior, vol. 5, no. 9, 2015. doi:10.1002/brb3.350
