Correlation between anosognosia and regional cerebral blood flow in Alzheimer's disease
ABSTRACT The purpose of this study was to determine the brain regions associated with anosognosia in Alzheimer's disease (AD). Anosognosia for memory disturbance was assessed in 29 probable AD patients, based on the discrepancy between questionnaire scores of the patients and their caregivers. In I-123-IMP single photon emission computed tomography (SPECT), a significant association was found between anosognosia and decreased perfusion in the orbitofrontal cortex, using regression analysis. This result is consistent with the previous studies that have reported an association between frontal dysfunction and anosognosia, and further suggests that the orbitofrontal cortex specifically associates with anosognosia in AD within the frontal cortex.
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- "Some studies demonstrate strong relationships between awareness and executive functioning [12, 19, 20, 27], with others reporting nonsignificant and trivial associations [19, 29]. Although clearly composite measures that rely on more basic cognitive functions, many summary scores from traditional tests of executive function are associated with the dorsolateral prefrontal circuit , and awareness has been associated with more midline [34–36] or orbitofrontal aspects of the prefrontal cortex . "
ABSTRACT: Awareness in dementia is increasingly recognized not only as multifactorial, but also as domain specific. We demonstrate differential clinical correlates for awareness of daily function, awareness of memory, and the novel exploration of awareness of balance. Awareness of function was higher for participants with mild cognitive impairment (aMCI and non-aMCI) than for those with dementia (due to Alzheimer disease; AD and non-AD), whereas awareness of memory was higher for both non-aMCI and non-AD dementia patients than for those with aMCI or AD. Balance awareness did not differ based on diagnostic subgroup. Awareness of function was associated with instrumental activities of daily living and caregiver burden. In contrast, awareness of balance was associated with fall history, balance confidence, and instrumental activities of daily living. Clinical correlates of awareness of memory depended on diagnostic group: associations held with neuropsychological variables for non-AD dementia, but for patients with AD dementia, depression and instrumental activities of daily living were clinical correlates of memory awareness. Together, these data provide support for the hypothesis that awareness and dementia are not unitary and are, instead, modality specific.Journal of aging research 01/2014; 2014:674716. DOI:10.1155/2014/674716
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- "Dorsolateral prefrontal hypoperfusion is involved in depression [5,6,7], whereas medial frontal or orbitofrontal hypoperfusion is devoted to apathy [7,8,9]. Delusion is closely related to decreased perfusion in the right frontal lobe [10,11,12], and anosognosia may be a reflection of functional impairment in the orbitofrontal or inferior frontal cortex [13,14,15]. The neural substrate of neuropsychological tests for patients with dementia has also been disclosed using brain SPECT data. "
ABSTRACT: The Trail Making Test (TMT) has long been used to investigate deficits in cognitive processing speed and executive function in humans. However, there are few studies that elucidate the neural substrates of the TMT. The aim of the present study was to identify the regional perfusion patterns of the brain associated with performance on the TMT part A (TMT-A) in patients with Alzheimer's disease (AD). Eighteen AD patients with poor performance on the TMT-A and 36 age- and sex-matched AD patients with good performance were selected. All subjects underwent brain single photon emission computed tomography. No significant differences between the good and poor performance groups were found with respect to years of education and revised Addenbrooke's Cognitive Examination scores. However, higher z-scores for hypoperfusion in the bilateral superior parietal lobule were observed in the group that scored poorly on the TMT-A compared with the good performance group. Our results suggest that functional activity of the bilateral superior parietal lobules is closely related to performance time on the TMT-A. Thus, the performance time on the TMT-A might be a promising index of dysfunction of the superior parietal area among mild AD patients.06/2013; 3(1):202-11. DOI:10.1159/000350806
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- "Most of the earlier studies showing only frontal involvement had actually adopted regions of interest approaches and only focused on frontal regions, limiting the possible interpretation. However, two studies demonstrated a unique frontal involvement using a whole brain approach (Shibata et al., 2008; Rosen et al., 2010 "
ABSTRACT: To review studies investigating the brain correlates of unawareness of cognitive and behavioural symptoms in people with dementia. A detailed search of the literature was conducted to include all the peer-reviewed studies published in English aimed at identifying the structural or functional brain correspondents of unawareness in dementia patients. Their results were interpreted in relation to the methodological differences in terms of type of dementia studied, the protocol adopted to measure lack of awareness, the imaging techniques employed, the experimental designs and statistical analyses performed. Eighteen studies undertaken to explore the functional and structural correlates of unawareness of cognitive symptoms in dementia were identified. Although their results showed a disparate range of brain correlates, they were mainly localized in frontal and temporo-parietal regions. Although the anatomical correlates of unawareness of disease in dementia have not yet been exhaustively explored, understanding the correlates of unawareness may also contribute to understand the brain correlates of self-awareness and self-reflection. We discuss the current knowledge base and consider potential future directions for research.International Journal of Geriatric Psychiatry 08/2011; 26(8):783-92. DOI:10.1002/gps.2620 · 3.09 Impact Factor