Anosognosia in mild cognitive impairment: Relationship to activation of cortical midline structures involved in self-appraisal

University of Wisconsin–Madison, Madison, Wisconsin, United States
Journal of the International Neuropsychological Society (Impact Factor: 2.96). 06/2007; 13(3):450-61. DOI: 10.1017/S1355617707070488
Source: PubMed


Awareness of cognitive dysfunction shown by individuals with Mild Cognitive Impairment (MCI), a condition conferring risk for Alzheimer's disease (AD), is variable. Anosognosia, or unawareness of loss of function, is beginning to be recognized as an important clinical symptom of MCI. However, little is known about the brain substrates underlying this symptom. We hypothesized that MCI participants' activation of cortical midline structures (CMS) during self-appraisal would covary with level of insight into cognitive difficulties (indexed by a discrepancy score between patient and informant ratings of cognitive decline in each MCI participant). To address this hypothesis, we first compared 16 MCI participants and 16 age-matched controls, examining brain regions showing conjoint or differential BOLD response during self-appraisal. Second, we used regression to investigate the relationship between awareness of deficit in MCI and BOLD activity during self-appraisal, controlling for extent of memory impairment. Between-group comparisons indicated that MCI participants show subtly attenuated CMS activity during self-appraisal. Regression analysis revealed a highly significant relationship between BOLD response during self-appraisal and self-awareness of deficit in MCI. This finding highlights the level of anosognosia in MCI as an important predictor of response to self-appraisal in cortical midline structures, brain regions vulnerable to changes in early AD.

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Available from: Carey Gleason, Aug 28, 2014
    • "In a group of MCI and mild dementia patients, anosognosia was related to worse global cognition, frontal lobe dysfunction, and brain single photon emission computed tomography (SPECT) abnormality in the right inferior frontal gyrus (Vogel, Hasselbalch, Gade, Ziebell, & Waldemar, 2005). An fMRI study of patients with MCI found that decreased awareness of cognitive deficits was associated with attenuated activation in the medial prefrontal cortex and posterior cingulate during a self-appraisal task (Ries et al., 2007). A recent study investigated possible neuroanatomical correlates of anosognosia in amnestic MCI and found that deficits in awareness were related to reduced grey matter volume in several areas including the anterior cingulate, inferior frontal cortex, and cerebellar vermis among individuals who ultimately converted to AD. "
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    ABSTRACT: A significant portion of individuals with mild cognitive impairment (MCI) experience limited awareness of cognitive deficits. Although older adults with epilepsy have comparable cognitive deficits to individuals with MCI, little is known about awareness of cognitive deficit in epilepsy. This study compared deficit awareness in epilepsy and MCI and examined its relationship with neuropsychological performance. Sixty-two older adults (31 epilepsy, 31 MCI) completed neuropsychological testing and the Cognitive Difficulties Scale (CDS), a self-report measure of everyday cognitive skills. Informants completed the CDS only. Cognitive domain scores were created. CDS composite scores were created by summing attention-concentration and language and delayed memory factors. Awareness was defined as the difference between patient and informant CDS scores, with limited awareness defined as greater informant complaints. Neuropsychological performance was similar between groups for all domains except that MCI participants had worse delayed memory, t(60) = 2.49, p < .05. CDS scores were similar between patient groups (p > .05). Epilepsy informant CDS scores were related to poorer immediate memory (r = -.41, p = .02). MCI informant CDS scores were related to worse delayed memory (r = -.41, p = .02). Limited awareness was found in 29.0% of epilepsy and 61.3% of MCI participants. Awareness was not related to cognition in epilepsy but was related to worse delayed memory (r = -.41, p = .02) for MCI participants. Older adults with epilepsy and MCI had similar cognitive deficits with the exception of greater impairment in delayed memory for MCI patients. There was less awareness of deficit in the MCI group, suggesting that delayed memory may be a critical factor for deficit awareness. Results argue against executive dysfunction as a major contributor to deficit awareness.
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    • "Most previous studies involved resting state rCBF-SPECT or rCMRglu-PET measurements and voxel-based morphometry (VBM) MRI. Only few studies collected fMRI scans during either a self-assessment or a go no-go task (Amanzio et al., 2011; Ries et al., 2007; Zamboni et al., 2013). The main finding of these studies was that anosognosia for one's own cognitive disability can be associated with some specific brain dysfunction, e.g., a frontal hypometabolism or hypoperfusion in the prefrontal cortex (PFC) (Derouesné et al., 1999; Hanyu et al., 2008; Harwood et al., 2005; Mendez & Shapira, 2005; Reed, Jagust, & Coulter, 1993; Salmon et al., 2006; Shibata, Narumoto, Kitabayashi, Ushijima, & Fukui, 2008;). "
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    ABSTRACT: Three cognitive components may play a crucial role in both memory awareness and in anosognosia for memory deficit (AMD): (1) a personal data base (PDB), i.e., a memory store that contains "semantic" representations about the self, (2) monitoring processes (MPs) and (3) an explicit evaluation system (EES), or comparator, that assesses and binds the representations stored in the PDB with information obtained from the environment. We compared both the behavior and the functional connectivity (as assessed by resting-state fMRI) of AMD patients with aware patients and healthy controls. We found that AMD is associated with an impoverished PDB, while MPs are necessary to successfully update the PDB. AMD was associated with reduced functional connectivity within both the default-mode network and in a network that includes the left lateral temporal cortex, the hippocampus and the insula. The reduced connectivity between the hippocampus and the insular cortex was correlated with AMD severity.
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    • "Part of the reason for this left-hemisphere assymetry may be that SA often recruits IS processes located in the LIFG (Morin and Hamper, 2012). Several researchers emphasize the importance of cortical midline structures (CMS; D'argembeau et al., 2008; Northoff, 2014; Ries et al., 2007; Summerfield, Hassabis and Maguire, 2009). Moran and colleagues (2013) suggest that CMS are specialized for representing any type of social information, including the self; they are also responsible for the direction of our thought processes on a moment-to-moment basis and represent a hub integrating information from disparate neural processing systems into a ―conscious workspace‖ (Baars, 2002). "

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