Semantic richness influences naming pictures in old age and in Alzheimer's disease

This study was designed to examine whether semantic richness influences the naming of living and non-living concepts in normal ageing and in Alzheimer's disease (AD). Eighteen young adults, 33 healthy older adults and 24 AD patients performed a picture naming task in which the pictures varied as a function of knowledge domain (living vs. non-living) and semantic richness (low vs. high number of features). Features were categorized according to their distinctiveness (distinctive and shared features) and informational nature (perceptual and functional features). As a whole, the results indicated that semantic richness influenced naming accuracy in normal ageing and in Alzheimer's disease. The healthy older adults and AD patients had lower performance than the young adults, and particularly for naming living things with a low number of features. These results provide evidence for the role of semantic richness in picture naming and for its differential impact on concept processing during normal and pathological ageing.