Semantic distance abnormalities in mild cognitive impairment: their nature and relationship to function

Area of Science:

• Neuroscience
• Cognitive Psychology
• Gerontology

Background:

• Mild cognitive impairment (MCI) is a transitional stage between normal aging and dementia.
• Understanding semantic system compromises in MCI is crucial for early diagnosis and intervention.
• Previous research has not fully clarified the relationship between semantic processing deficits and functional decline in MCI.

Purpose of the Study:

• To directly investigate semantic system impairments in individuals with amnestic mild cognitive impairment (aMCI).
• To explore the relationship between these semantic deficits and everyday functional competencies.
• To differentiate semantic processing in aMCI from that in mild-to-moderate Alzheimer's disease (AD) and healthy controls.

Main Methods:

• A cohort of 25 aMCI patients, 27 mild/moderate AD patients, and 70 healthy controls participated.
• A novel semantic distance task assessed decision-making with word and image stimuli varying in physical size.
• Everyday functional competence was evaluated using a performance-based measure.

Main Results:

• Both aMCI and AD groups showed reduced accuracy and slower reaction times compared to controls on word-based semantic tasks.
• Performance disproportionately declined in aMCI and AD groups when judging the semantic attribute of size.
• Perceptual information (drawing size) unduly influenced semantic judgments in aMCI and AD groups when using image stimuli.
• Semantic task performance significantly predicted functional competence in aMCI and AD groups.

Conclusions:

• Evidence supports semantic system compromises in aMCI, independent of retrieval or access issues.
• Perceptual information intrudes on semantic processing in aMCI and AD.
• Semantic impairments are robustly linked to functional difficulties in everyday life for individuals with aMCI.