An analysis of 6 studies found an increased risk of all-cause dementia among patients with any headache. However, no association was found between headache and Alzheimer disease.
Currently, identified risk factors include obesity, diabetes, hypertension, lipid metabolism disorders, coronary heart disease, and heart failure. Now, researchers have indicated that any headache is associated with an increased risk of all-cause dementia. However, the analysis of 6 studies covering 291,549 people found that migraine was not statistically significantly associated with an increased risk of Alzheimer disease.
Overall, history of any headache was associated with an increased risk of all-cause dementia (relative risk [RR] = 1.24; 95% CI: 1.09-1.41), but there was considerable heterogeneity across studies. According to the researchers, neither subgroup analysis by sample size nor study design could explain the reason behind the heterogeneity, and a sensitivity analysis showed that none of the individual studies had an evident influence on the pooled-effect size.
The association between headache disorders and dementia remains largely unknown, but several mechanisms have been speculated to be involved. Headache is a common pain disorder, and previous research has found that several brain structures involved in the pain network undergo metamorphic changes during the disease process. The authors noted that these brain regions also play important roles in the memory network.
Another hypothesis comes from reports that there is an association of white-matter hyperintensity with an increased risk of dementia. “Incidentally, headache patients are reported to have increased risk of white-matter hyperintensity,” wrote the researchers, who explained that subtle changes in the brain white-matter might contribute to an increased risk of dementia in these patients.
Three of the 6 studies focused on migraine specifically, and after pooling the effect of the condition, the researchers found an RR of 1.28 (95% CI: 0.64-2.54) for all-cause dementia. Only 1 study demonstrated an association between migraine and an increased risk of Alzheimer disease, showing a RR of 4.22 (95% CI: 1.59-10.42).
“It should be noted that no statistically significant result was found in the pooled analysis of the association between migraine and all-cause dementia,” wrote the researchers. “However, the result of this analysis was based on only 3 studies and 2 were abstracts, and as such, should be interpreted with caution.”
They added that although current available evidence on migraine and dementia were scarce, it could suggest that a possible association might exist and highlights the need for more population-based research on this association.
Wang J, Xu W, Sun S, Yu S, Fan L. Headache disorder and the risk of dementia: a systematic review and meta-analysis of cohort studies [published online October 11, 2018]. J Headache Pain. doi: 10.1186/s10194-018-0925-4.