Detecting dementia early on and starting treatment as soon as possible can improve the effectiveness of therapies and empower people with the condition and their families to make the right decisions at the right time.
Suzanne L. Tyas, Ph.D., of the University of Waterloo, in Ontario, Canada, is the senior author of the new paper, which appears in the International Journal of Geriatric Psychiatry.
Tyas and colleagues’ analysis included 679 community-dwelling study participants aged 65 or older who contributed data to the Manitoba Study of Health and Aging — a prospective cohort study that included only participants who were “cognitively intact” at baseline.
The researchers had access to complete data on the migraine histories of these participants. They assessed the associations between migraine, potentially confounding factors — such as age, gender, education, and a history of depression — and all-cause dementia and dementia subtypes, such as Alzheimer’s disease and vascular dementia.
Intervening variables are hypothetical factors that may explain the causal relationship between two other variables. For instance, high blood pressure could explain an association between migraine and increased dementia risk.
The analysis revealed significant associations between migraine and all-cause dementia and Alzheimer’s, “even after adjustment for confounding and intervening variables.”
Specifically, the odds of having migraine were nearly three times higher in people with dementia than those without dementia. The odds of migraine were slightly more than four times higher in those with Alzheimer’s than in those without it.
“Migraines were a significant risk factor for [Alzheimer’s] and all‐cause dementia,” conclude the authors.
The study did not find an association with vascular dementia, however. “Despite the vascular mechanisms involved in migraine physiology, migraines were not significantly associated with [vascular dementia] in this study.”
“We don’t yet have any way to cure Alzheimer’s disease, so prevention is key. […] Identifying a link to migraines provides us with a rationale to guide new strategies to prevent Alzheimer’s disease.”
Suzanne L. Tyas, Ph.D.
The scientists list some limitations to their research. Among them is the fact that the participants self-reported the occurrence of their migraine symptoms, rather than receiving medical diagnoses in compliance with criteria established by an organization such as the International Headache Society (IHS).
However, say the authors, “Self‐reported migraine has been shown to have excellent agreement with the IHS.”
Another limitation is that the research did not differentiate between migraine with and without aura, and some studies have suggested that there are more severe cognitive consequences to migraine with aura.
However, the researchers “found a significant association between migraines and [Alzheimer’s disease] despite the inclusion of migraine without aura in the general migraine measure.”
“The inclusion of migraine without aura would dilute this effect if migraine with aura causes greater neurological damage, and thus, our findings that individuals with [Alzheimer’s] were four times more likely to have a history of migraines may be a conservative estimate,” they write.
Furthermore, the fact that there were no “male participants with migraines who developed dementia” in the study means that it was not possible to assess how gender modified the association between migraine and dementia.