Anosognosia for Behavioral Disturbances in Frontotemporal Dementia and Corticobasal Syndrome: A Voxel-Based Morphometry Study

Abstract

Background: Patients with syndromes of the frontotemporal dementia spectrum are frequently unaware of their behavioral changes. Methods: Seventy patients with a clinical diagnosis of behavioral variant frontotemporal dementia (bv-FTD, n = 27), aphasic variant frontotemporal dementia (a-FTD, n = 12) and corticobasal syndrome (CBS, n = 31) participated in the study. Anosognosia for behavioral disturbances was measured as discrepancy between caregiver’s and patient’s ratings on the Frontal Systems Behavior Scale for present and premorbid behavioral symptoms. Voxel-based morphometry analysis of MRI data was performed to explore the association between anosognosia and gray matter loss. Results: Although behavioral symptoms were reported in all the groups, the comparison between present and premorbid anosognosia revealed that bv-FTD patients not only underestimated their present behavioral disturbances compared to their caregivers, but also overestimated their premorbidbehavioral disturbances. Across all groups, the degree of anosognosia for present behavioral impairment correlated with gray matter atrophy in a posterior region of the right superior temporal sulcus (adjacent to the temporoparietal junction). Conclusion: These results confirm the role of the right temporoparietal cortex in the genesis of anosognosia and suggest that, in clinical syndromes of the frontotemporal dementia spectrum, anosognosia is associated with the dysfunction of temporoparietal mechanisms of self versus others knowledge.

Self-Rated Anosognosia Score May Be a Sensitive and Predictive Indicator for Progressive Brain Atrophy in Amyotrophic Lateral Sclerosis: An X-Ray Computed Tomographic Study

“…In our study, while the median anosognosia scores were –1 (range –3 to 0) in HT patients, the scores were –1 (range –4 to 3) and 4.5 (range 3–18) in ALS patients without and with FTLD, respectively, with a significant difference between the groups. This result is in agreement with the finding of Zamboni et al [15] that patients with a behavioral variant of FTD (bv-FTD) underestimated their level of behavioral disturbance.…”

“…The anosognosia scale [8] is so simple that patients with severe physical disability are able to complete the tests, whereas completion of the MMSE and FAB are limited to certain patients. Several tests have been used to evaluate anosognosia, including the Frontal Systems Behavior Scale (FrSBe) and the Interpersonal Adjectives Scale [6,14,15]. Using the FrSBe, Woolley et al [6] found that ALS patients with FTD exhibited a profound lack of insight compared to those without FTD, and it is of interest that we found a similar result using the much simpler anosognosia scale.…”

“…In addition, studies on bv-FTD have shown that anosognosia is correlated with hypoperfusion in the left temporal pole [1] and right frontal regions [3]. Recently, Zamboni et al [15] used FrSBe and voxel-based morphometry to show that the degree of anosognosia correlated with gray matter atrophy in a posterior region of the right superior temporal sulcus (adjacent to the temporoparietal junction). A pathological study on AD by Marshall et al [21] showed that the density of amyloid plaques in the right presubiculum (transitional zone between the subiculum and the adjacent CA1 region of the hippocampus) correlated with anosognosia for AD.…”

Self-awareness in neurodegenerative disease relies on neural structures mediating reward-driven attention

“…Impaired awareness for behavioural deficits has been previously associated with right temporal atrophy (Zamboni and Wilcock, 2011;Sollberger et al, 2014). A proposed mechanism for this finding was that impaired empathy and understanding of others' minds, frequently associated with right temporal atrophy, affects the ability to understand others' reactions to one's inappropriate behaviour, and to update one's self-knowledge accordingly (Zamboni et al, 2010). Poor metacognitive awareness has been directly related to impaired empathy (O'Keeffe et al, 2007).…”

“…Patients with FTD with right frontal hypoperfusion experience more changes in their self-perceptions (Miller et al, 2001;Mendez and Shapira, 2005), and anosognosia for memory loss in patients with Alzheimer's disease is correlated with right dorsolateral PFC hypoperfusion (Reed et al, 1993). Some studies have also reported the involvement of atrophy in left orbitofrontal (Salmon et al, 2006;Shibata et al, 2008), and temporal and parietal regions (Ries et al, 2007;Zamboni et al, 2010).…”