Taudorf L, et al. - In an entire national population over a 20-year period, researchers examined registry-based time trends in incidence and prevalence rates of dementia. Utilizing longitudinal data from nationwide registries on dementia status and demographics on all residents ≥ 65 years old in Denmark, annual incidence and prevalence were evaluated. The population included 2 million people, 152,761 of whom were diagnosed with dementia. According to findings, the age- and gender-adjusted incidence rate increased annually by 9% from 1996 to 2003 on average, followed by an annual decrease of 2%, while the overall prevalence increased over the entire period. This is the first research to report on the occurrence and prevalence of continuous-time trends in an entire national population. Since 2003, the incidence rate has steadily declined, while the overall prevalence continues to increase. These results should be taken into account in future healthcare planning on dementia prevention and treatment.