Dementia incidence in Quebec over 20 years

Plain Language Summary

We looked at how many people in Quebec, aged 40 years old and above, were newly diagnosed with dementia over a period of twenty years, from 2003-04 to 2022-23. We used data from health administrative databases. We found that the rate of people developing dementia (incidence) over this period of time remained stable, that is, there were no major increases or decreases. Many high-income countries have reported reductions in incidence over time, which contrasts with the stable incidence we found in Quebec.

It is possible that incidence did not decline in Quebec due to poor public health strategies that failed to reduce smoking, improve education, or manage cardiovascular conditions. However, given the improvements that have been made in dementia care in Quebec (especially since the Quebec Alzheimer Plan was implemented), it is more likely that improvements in dementia care practices, in particular diagnostic practices, are why incidence did not decline. Improved practices in diagnosing people could have meant that the number of people who went undiagnosed in 2003-04 was higher than the amount of people who did not receive a diagnosis in 2022-23: therefore, dementia incidence in Quebec might have declined, but improvements in diagnosis could have masked this decline and made dementia incidence appear stable.