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J Alzheimers Dis. 2015;46(1):187-98. doi: 10.3233/JAD-142703.

"Knowing What You Don't Know": Language Insight in Semantic Dementia.

Savage SA1,2,3, Piguet O1,2,3, Hodges JR1,2,3.

Author information

Neuroscience Research Australia, Sydney, Australia.
Faculty of Medicine, School of Medical Sciences, University of New South Wales, Sydney, Australia.
ARC Centre of Excellence in Cognition and its Disorders, University of New South Wales, Sydney, Australia.



Reduced insight commonly occurs in dementia and can be specific to one area of functioning. Despite recent models identifying a role for semantic memory, little investigation of insight has been conducted in semantic dementia (SD), with patients often described as being aware of their language problems.


This study aims to investigate language insight in SD.


Twenty-two SD (nā€Š=ā€Š11 severe, nā€Š=ā€Š11 mild-moderate) and 9 nonfluent primary progressive aphasic patients completed three experimental language tasks to assess knowledge and awareness of certain words. Skills in evaluating language were tested by comparing performance ratings on the Cookie Theft task with objective scoring. Awareness regarding the existence and previous use of certain words was tested using two additional tasks.


While SD patients were as accurate as nonfluent patients in rating their own performance on the Cookie Theft immediately following the task, they were significantly poorer at evaluating the same content re-recorded, or other examples of poor language. Compared to nonfluent patients, severe SD patients also made more errors identifying previously known low frequency words. Lastly, when tested on labels for specific aspects of an object, only SD patients made errors regarding the existence, or their past knowledge, of certain words.


SD patients show a general awareness of their language impairments, but have difficulty evaluating language content. These difficulties adversely affect the ability to reflect upon current and past language skills producing an under-awareness of language deficits. This mild, secondary form of anosognosia appears to increase with greater levels of semantic impairment.


Anosognosia; cognitive awareness; frontotemporal dementia; primary progressive aphasia; self-appraisal

[Indexed for MEDLINE]

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