Headache disorder and the risk of dementia: a systematic review and meta-analysis of cohort studies.

BACKGROUND: Until now, headache disorders have not been established as a risk factor for dementia. The aim of this study was to determine whether headache was associated with an increased risk of dementia. METHODS: We systematically searched electronic databases, including PubMed, Embase, and Web of Science, for studies investigating the association between headache and dementia. We then conducted a meta-analysis to determine a pooled-effect estimate of the association. RESULTS: We identified 6 studies (covering 291,549 individuals) to investigate the association between headache and the risk of all-cause dementia or Alzheimer's disease (AD). Pooled analyses showed that any headache was associated with a 24% greater risk of all-cause dementia (relative risk [RR] = 1.24; 95% confidential interval [CI]: 1.09-1.41; P = 0.001), and that any headache was not statistically significantly associated with an increased risk of AD (RR = 1.47; 95% CI: 0.82-2.63; P = 0.192). CONCLUSIONS: Our results indicated that any headache was associated with an increased risk of all-cause dementia. However, additional studies are warranted to further confirm and understand the association.