Loss of Insight in Primary Progressive Aphasia and Behavioral Variant Frontotemporal Dementia

Sarah Banks

doi:https://doi.org/10.21985/N22H8B

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Loss of Insight in Primary Progressive Aphasia and Behavioral Variant Frontotemporal Dementia

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"Anosognosia" or lack of insight into one's own illness is not uncommon in central nervous system disease. Neurodegenerative diseases of the brain that cause dementia are often associated with anosognosia. A lot is known about anosognosia in Alzheimer's disease but relatively little is known about lack of insight into illness in other forms of dementia such as those caused by frontotemporal degeneration. The frontotemporal dementias (FTDs) encompass two phenotypes that are quite distinct in their initial presentation. The behavioral variant (bvFTD) initially manifests as a change in personality or conduct sometimes accompanied by executive impairments. The language variant (primary progressive aphasia - PPA) results in a fairly isolated decline in language abilities over the first two years. Although lack of insight is a designated core characteristic of bvFTD, it has not been well studied in bvFTD or in PPA. This review introduces the reader to anosognosia and its manifestations in neurological disease. Problems with definitions and explanatory hypotheses are examined. A brief discussion of the anatomical areas that appear to be important in maintaining insight follows, with relevance to those areas affected by bvFTD and PPA. Studies of insight in other forms of dementia (mostly AD) will be reviewed in light of their possible contribution to our understanding of insight in bvFTD and PPA. Techniques used to assess the patient's insight will be critiqued, and the small literature on insight in the FTDs will be discussed in detail. Finally the three studies that comprise this dissertation will be introduced. Study 1 assesses insight both from a general perspective and a symptom-specific perspective, by comparing patients' report of symptoms with that of their caregivers. Study 2 breaks insight down into its metacognitive components, and compares self-awareness and self-monitoring across a range of domains. Study 3 investigates the cognitive correlates of reduction of insight in PPA patients alone.

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