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

Area of Science:

• Neuroscience
• Cognitive Psychology
• Linguistics

Background:

• Reduced insight is common in dementia, often specific to certain functions.
• Semantic dementia (SD) has been under-investigated regarding insight, despite its impact on semantic memory.
• Patients with SD are often perceived as aware of their language difficulties.

Purpose of the Study:

• To investigate language insight in patients with semantic dementia (SD).
• To assess awareness and knowledge of words in SD patients.
• To evaluate the relationship between semantic impairment and insight into language deficits.

Main Methods:

• Twenty-two SD patients (11 severe, 11 mild-moderate) and 9 nonfluent primary progressive aphasic patients participated.
• Three experimental language tasks assessed knowledge and awareness of specific words.
• Language evaluation skills were tested by comparing self-ratings with objective scoring on the Cookie Theft task.

Main Results:

• SD patients showed similar immediate performance ratings but poorer evaluation of re-recorded or other poor language samples compared to controls.
• Severe SD patients made more errors identifying low-frequency words.
• SD patients exhibited errors in recognizing the existence or prior knowledge of specific object labels.

Conclusions:

• SD patients possess general awareness of language impairments but struggle with content evaluation.
• Difficulties in evaluating language lead to under-awareness of deficits, a mild, secondary anosognosia.
• The degree of semantic impairment correlates with the severity of this language insight deficit.