..We investigated the association between dementia diagnosis and recording of insomnia symptoms 5–10 years earlier in primary care.
..We ascertained the presence of insomnia symptoms during a five-year period starting 10 years before the index date. Odds ratios for developing dementia were estimated using logistic regression after controlling for hypnotic exposure and physical and mental health comorbidities.
Results: The adjusted odds ratio for dementia in those with previous insomnia was 1.34 (95% CI = 1.20–1.50).
Conclusion: There is an association between dementia and previous insomnia. It may be possible to incorporate insomnia into predictive tools for dementia.