Dementia incidence dropping while overall prevalence continues to climb

While dementia incidence may be declining over time, its overall prevalence keeps on rising, reports a recent Denmark study.

Accessing the National Patient Registry and the Danish Psychiatric Central Research Register, researchers evaluated the longitudinal trends in dementia status in a population of almost 2 million adults aged ≥65 years. Data analysis was performed between the years 1996 and 2015.

Overall, 152,761 individuals were diagnosed with dementia over 16,944,630 person-years of observation. A total of 170,478 patients had been living with dementia during the 20-year study period. In the same time span, the elderly population jumped from 803,334 in 1996 to 1,055,984 in 2015, but the median age dropped from 74.2 to 72.9 years.

Incidence rates of dementia were significantly higher in 2015 than in 1996. However, this was driven mostly by a steep growth in the number of cases between 1996 to 2003, followed by an unstable plateau until 2010. In the years approaching 2015, dementia incidence dropped moderately.

Adjusting for age and sex, dementia incidence increased by an annual average of 9 percent from 1996 to 2003 and dropped by a yearly mean of 2 percent from 2004 to 2015.

This trend in incidence was accompanied by a steady increase in overall dementia prevalence, regardless of sex and age group. The number of patients with dementia grew from 14,019 in 1996 to 36,129 in 2015, with the rate of increase slowing down in the most recent years.