Objective:

To estimate the effect of different durations of treatment with specific antihypertensive drugs that exhibit anticholinergic properties on the risk of vascular dementia and Alzheimer’s disease.

Key Findings:

• Null results for dementia risk comparing 3-6 years vs ≤3 years, indicating no significant difference.
• 10-year risk ratio for vascular dementia with >6 years vs ≤3 years was 0.69 (95% CI, 0.54-0.90), suggesting a potential protective effect.
• 10-year risk ratio for Alzheimer’s disease with >6 years vs ≤3 years was 0.91 (95% CI, 0.77-1.10), indicating no significant protective effect.

Interpretation:

Longer duration of treatment with antihypertensive drugs exhibiting anticholinergic properties may provide a modest benefit in reducing the risk of vascular dementia, defined as a clinically meaningful reduction in risk.

Limitations:

• Potential biases inherent in observational data, such as confounding factors and selection bias.
• Challenges in accurately emulating a target trial, including limitations in data quality and completeness.

Conclusion:

The study underscores the importance of treatment duration in evaluating dementia risk and highlights the utility of target trial emulation to mitigate selection bias, suggesting that clinicians should consider treatment duration when prescribing antihypertensive medications.