Analysing Realistic effects of modifiable risk factors for dementia in a large National Dataset.

BACKGROUND

Modifiable risk factors affect 40% of dementia risk thus creating an opportunity for prevention or delay. The risk factor life-course model of dementia prevention by the Lancet Commission has yet to be tested in the general populations. We aimed to assess the model's assumptions in a large national dataset of older adults assessed for support services.

METHODS

The interRAI assessment is a comprehensive evidence-based tool encompassing 236 items that is mandatory in New Zealand (NZ) for older adults providing a standardized national dataset. We tested the Lancet model of dementia prevention in a sample of 66,638 participants who underwent an interRAI assessment during the period 2013-2018. There were 59% female interviewees; mean age was 82 years (range: 65-107). Our cross-sectional dataset analysis was performed in using a logistic regression model with diagnosis of dementia as the primary outcome.

RESULTS

The Lancet prevention model was supported in part. Hypertension, Hearing Impairment and past or present Depression increase risk of dementia. Age - increased risk demonstrated until 85 years; Gender - females at increased risk; BMI - initial effect of high BMI increases risk of dementia. However, exercise, diabetes, vision impairment and smoking as modifiable factors were not associated with dementia risk as predicted by the Lancet model.

CONCLUSIONS

Limitations of the dataset analysed may have affected our findings. Nevertheless, important modifiable factors are herein confirmed as increasing dementia risk. BMI, hypertension, hearing impairment and depression are risks confirmed in the older NZ population lending credibility to prevention efforts targeted at these variables.