Abstract
INTRODUCTION: Early-onset Alzheimer's disease dementia (EOAD) is characterized by more pronounced cognitive decline than late-onset AD dementia (LOAD). Characteristic performance in spoken language remains undefined. METHOD: A cross-sectional analysis of 1189 people with EOAD and 4646 with LOAD from the National Alzheimer's Coordinating Center (NACC) was conducted. RESULT: Based on data from their first NACC visit with AD, there was considerable heterogeneity in language performance across people with EOAD and LOAD. The distribution of naming ability was similar across these groups. On average, people with LOAD performed better than those with EOAD in category fluency, letter fluency, and spoken lexical retrieval, and had lower Clinical Dementia Rating (CDR) Language scores, although there was considerable overlap in the distributions for participants with EOAD and those with LOAD. DISCUSSION: At diagnosis, the language profiles of EOAD and LOAD are distinct. There is substantial variability in both groups in multiple aspects of language. HIGHLIGHTS: Early-onset Alzheimer's disease (EOAD) is associated with significantly poorer category and phonemic fluency and global spoken lexical retrieval compared to late-onset Alzheimer's disease (LOAD) at time of diagnosis. Participants with EOAD dementia show greater severity and variability in clinician-rated language functioning, as measured by Clinical Dementia Rating (CDR) Language scores. No significant group differences were observed in confrontation naming performance between EOAD and LOAD dementia. Findings support that there are distinct profiles of language performance in EOAD and LOAD at time of dementia diagnosis.