In a population-based cohort of 2,282 dementia-free adults aged 60 years or older, anemia was associated with higher levels of Alzheimer disease–related blood biomarkers and a 66% higher hazard of developing dementia over a mean follow-up of 9.3 years. Lower hemoglobin levels were linked to greater dementia risk in a nonlinear pattern, and the highest risk was observed when anemia co-occurred with elevated biomarkers, particularly neurofilament light chain.