Word-list generation deficits in dementia

Area of Science:

• Neurology
• Cognitive Neuroscience
• Psycholinguistics

Background:

• Alzheimer's disease (AD) is characterized by cognitive decline, including deficits in language and memory.
• Semantic fluency tasks assess the ability to retrieve words from specific categories, while phonemic fluency tasks assess retrieval based on word initial sounds.
• Previous research suggests semantic fluency may be particularly vulnerable in neurodegenerative diseases.

Purpose of the Study:

• To determine if the semantic fluency deficit observed in Alzheimer's disease (AD) is specific to this condition.
• To compare the performance of patients with AD, Huntington's disease (HD), and vascular dementia (VD) against healthy controls on semantic and phonemic fluency tasks.

Main Methods:

• A comparative study design was employed.
• Participants included patients diagnosed with AD, HD, and VD, along with age-matched healthy controls.
• Performance was assessed using category (semantic) and first-letter (phonemic/lexical) word list generation tasks.

Main Results:

• All patient groups (AD, HD, VD) exhibited a significantly greater impairment in semantic fluency compared to phonemic fluency, relative to healthy controls.
• The severity of dementia did not alter the observed pattern of greater semantic than phonemic fluency impairment.
• This pattern suggests a common underlying mechanism across different dementia types.

Conclusions:

• The semantic fluency deficit is not specific to Alzheimer's disease but is a common feature across multiple dementia types, including Huntington's disease and vascular dementia.
• Impaired organization of semantic memory and difficulties in long-term retrieval likely contribute to the observed semantic fluency deficits.
• These findings highlight the broad impact of neurodegenerative processes on semantic memory systems.