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摘要
Context: A high ratio of plasma amyloid-beta peptide 40 (A beta(40)) to A beta(42), determined by both high A beta(40) and low A beta(42) levels, increases the risk of Alzheimer disease. In a previous study, we reported that depression is also associated with low plasma A beta(42) levels in the elderly population.
Objective: To characterize plasma A beta(40):A beta(42) ratio and cognitive function in elderly individuals with and without depression.
Design: Cross-sectional study.
Setting: Homecare agencies.
Participants: A total of 995 homebound elderly individuals of whom 348 were defined as depressed by a Center for Epidemiological Studies Depression score of 16 or greater.
Main Outcome Measures: Cognitive domains of memory, language, executive, and visuospatial functions according to levels of plasma A beta(40) and A beta(42) peptides.
Results: Subjects with depression had lower plasma A beta(42) levels (median, 14.1 vs 19.2 pg/mL; P=.006) and a higher plasma A beta(40):A beta(42) ratio (median, 8.9 vs 6.4; P<.001) than did those without depression in the absence of cardiovascular disease and antidepressant use. The interaction between depression and plasma A beta(40):A beta(42) ratio was associated with lower memory score (beta=-1.9, SE=0.7, P=.006) after adjusting for potentially confounders. Relative to those without depression, "amyloid-associated depression," defined by presence of depression and a high plasma A beta(40):A beta(42) ratio, was associated with greater impairment in memory, visuospatial ability, and executive function; in contrast, nonamyloid depression was not associated with memory impairment but with other cognitive disabilities.
Conclusion: Amyloid-associated depression may define a subtype of depression representing a prodromal manifestation of Alzheimer disease.
- 出版日期2008-5
