What are the neural correlates of meta-cognition and anosognosia in Alzheimer's disease? A systematic review

Abstract

Awareness of one's own cognitive processes (metacognition) or of one's own illness or deficits (anosognosia) can be impaired in people with Alzheimer's disease (AD). The neural correlates of anosognosia within AD remain inconclusive. Understanding anosognosia is of importance because of its impact on carer burden and increased institutionalization. A systematic review of structural and functional neuroimaging studies was conducted to identify specific brain regions associated with anosognosia within AD. Thirty-two studies were included in the systematic review. Reduced gray matter density, cerebral blood flow, and hypometabolism in 8 key regions were significantly associated with increased anosognosia scores in people with AD. The most frequently associated regions were the inferior frontal gyrus, anterior cingulate cortex, and medial temporal lobe. Other key regions include the superior frontal gyrus, medial frontal gyrus, orbitofrontal cortex, posterior cingulate cortex, and the insula. Identifying brain regions associated with anosognosia can aid understanding and identification of anosognosia in people with AD and potentially facilitate improvements in care.

Keywords: Alzheimer's disease; Anosognosia; Neural-correlates; Neuroimaging; Systematic review.

Fig. 1

PRISMA flowchart of included studies. Abbreviations: AD, Alzheimer's disease; PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

Fig. 2

Schematic representation of key brain regions significantly associated with anosognosia or metacognition from at least 2 structural studies.

Fig. 3

Schematic representation of key brain regions significantly associated with anosognosia from at least 2 functional modalities.

Fig. 4

Schematic representation of overall key brain regions significantly associated with anosognosia—across at least 2 structural and 2 functional studies.