Mid- to late-life migraine diagnoses and risk of dementia: a national register-based follow-up study

Genetic evidence for causal association between migraine and dementia: a mendelian randomization study

BACKGROUND

There is an association between migraine and dementia, however, their causal relationship remains unclear. This study employed bidirectional two-sample Mendelian randomization (MR) to investigate the potential causal relationship between migraine and dementia and its subtypes: Alzheimer's disease (AD), vascular dementia (VaD), frontotemporal dementia (FTD), and dementia with Lewy bodies (DLB).

METHODS

Summary-level statistics data were obtained from publicly available genome-wide association studies (GWAS) for both migraine and five types of dementia. Single nucleotide polymorphisms (SNPs) associated with migraine and each dementia subtype were selected. MR analysis was conducted using inverse variance weighting (IVW) and weighted median (WM) methods. Sensitivity analyses included Cochran's Q test, MR pleiotropy residual sum and outlier (MR-PRESSO) analysis, the intercept of MR-Egger, and leave-one-out analysis.

RESULTS

Migraine showed a significant causal relationship with AD and VaD, whereas no causal relationship was observed with all-cause dementia, FTD, or DLB. Migraine may be a potential risk factor for AD (odds ratio [OR]: 1.09; 95% confidence interval [CI]: 0.02-0.14; P = 0.007), while VaD may be a potential risk factor for migraine (OR: 1.04; 95% CI: 0.02-0.06; P = 7.760E-5). Sensitivity analyses demonstrated the robustness of our findings.

CONCLUSION

Our study suggest that migraine may have potential causal relationships with AD and VaD. Migraine may be a risk factor for AD, and VaD may be a risk factor for migraine. Our study contributes to unraveling the comprehensive genetic associations between migraine and various types of dementia, and our findings will enhance the academic understanding of the comorbidity between migraine and dementia.

Mind the Metabolic Gap: Bridging Migraine and Alzheimer's disease through Brain Insulin Resistance

Brain insulin resistance has recently been described as a metabolic abnormality of brain glucose homeostasis that has been proven to downregulate insulin receptors, both in astrocytes and neurons, triggering a reduction in glucose uptake and glycogen synthesis. This condition may generate a mismatch between brain's energy reserve and expenditure, mainly during high metabolic demand, which could be involved in the chronification of migraine and, in the long run, at least in certain subsets of patients, in the prodromic phase of Alzheimer's disease, along a putative metabolic physiopathological continuum. Indeed, the persistent disruption of glucose homeostasis and energy supply to neurons may eventually impair protein folding, an energy-requiring process, promoting pathological changes in Alzheimer's disease, such as amyloid-β deposition and tau hyperphosphorylation. Hopefully, the "neuroenergetic hypothesis" presented herein will provide further insight on there being a conceivable metabolic bridge between chronic migraine and Alzheimer's disease, elucidating novel potential targets for the prophylactic treatment of both diseases.

Genetic evidence for the causal relationships between migraine, dementia, and longitudinal brain atrophy

BACKGROUND

Migraine is a neurological disease with a significant genetic component and is characterized by recurrent and prolonged episodes of headache. Previous epidemiological studies have reported a higher risk of dementia in migraine patients. Neuroimaging studies have also shown structural brain atrophy in regions that are common to migraine and dementia. However, these studies are observational and cannot establish causality. The present study aims to explore the genetic causal relationship between migraine and dementia, as well as the mediation roles of brain structural changes in this association using Mendelian randomization (MR).

METHODS

We collected the genome-wide association study (GWAS) summary statistics of migraine and its two subtypes, as well as four common types of dementia, including Alzheimer's disease (AD), vascular dementia, frontotemporal dementia, and Lewy body dementia. In addition, we collected the GWAS summary statistics of seven longitudinal brain measures that characterize brain structural alterations with age. Using these GWAS, we performed Two-sample MR analyses to investigate the causal effects of migraine and its two subtypes on dementia and brain structural changes. To explore the possible mediation of brain structural changes between migraine and dementia, we conducted a two-step MR mediation analysis.

RESULTS

The MR analysis demonstrated a significant association between genetically predicted migraine and an increased risk of AD (OR = 1.097, 95% CI = [1.040, 1.158], p = 7.03 × 10- 4). Moreover, migraine significantly accelerated annual atrophy of the total cortical surface area (-65.588 cm2 per year, 95% CI = [-103.112, -28.064], p = 6.13 × 10- 4) and thalamic volume (-9.507 cm3 per year, 95% CI = [-15.512, -3.502], p = 1.91 × 10- 3). The migraine without aura (MO) subtype increased the risk of AD (OR = 1.091, 95% CI = [1.059, 1.123], p = 6.95 × 10- 9) and accelerated annual atrophy of the total cortical surface area (-31.401 cm2 per year, 95% CI = [-43.990, -18.811], p = 1.02 × 10- 6). The two-step MR mediation analysis revealed that thalamic atrophy partly mediated the causal effect of migraine on AD, accounting for 28.2% of the total effect.

DISCUSSION

This comprehensive MR study provided genetic evidence for the causal effect of migraine on AD and identified longitudinal thalamic atrophy as a potential mediator in this association. These findings may inform brain intervention targets to prevent AD risk in migraine patients.

Independent causal effect of migraines on Alzheimer's disease risk: a multivariate Mendelian randomization study

Background

The observational studies investigated the impact of migraine on Alzheimer's Disease (AD). However, these findings were limited by confounding factors and reverse causation, leading to contradictory results.

Methods

We utilized Univariable Mendelian Randomization (UVMR) to explore the link between migraine (13,971 cases/470,627 controls) and AD risk (Bellenguez et al., 39,106 cases/46,828 controls; FinnGen, 111,471 cases/111,471 controls). Meta-analysis was performed for comprehensive synthesis. Employing Multivariable Mendelian Randomization (MVMR), we created models incorporating migraine and 35 potential AD risk factors, examining migraine's independent impact on AD onset risk under considering these factors.

Results

The meta-analysis of inverse variance weighted MR results, combining data from Bellenguez et al. (odds ratio (OR) [95% confidence interval (CI)]: 1.5717 [1.1868-2.0814], p = 0.0016) and FinnGen (OR [95% CI]: 1.2904 [0.5419-3.0730], p = 0.5646), provided evidence for a causal relationship between genetically predicted migraine and the heightened risk of AD occurrence (OR [95% CI]: 1.54 [1.18, 2.00], p < 0.01). After adjusting for Diastolic blood pressure (OR [95% CI]: 1.4120 [0.8487-2.3493], p = 0.1840) and Tumor necrosis factor alpha (OR [95% CI]: 1.2411 [0.8352-1.8443], p = 0.2852), no discernible association was detected between migraine and the risk of AD.

Conclusion

This study offers compelling evidence indicating a significant correlation between genetically predicted migraine and an elevated risk of AD.

Association between chronic pain and dementia: a systematic review and meta-analysis

PURPOSE

Dementia and chronic pain (CP) are prevalent among older adults. However, no study has systematically reviewed the association between dementia and CP. Therefore, we performed this study to gather evidence about the potential relationship between the two.

METHODS

Two authors independently searched PubMed, Embase, and Web of Science to identify all records published up to 1 September 2022 that explored the association between CP and dementia. The methodological quality of the studies was assessed using the Newcastle Ottawa Scale (NOS). A fixed or random-effects model was used to pool the risk estimates.

RESULTS

Among the initial 3296 articles retrieved, 19 were included in the review (1 cross-sectional, and 18 cohort). The pooled result showed the risk of dementia was 1.42 times higher in CP patients (HR = 1.42, 95% CI 1.23-1.64, P < 0.001). dementia and CP subtypes, gender, and age did not significantly affect the results.

CONCLUSION

Our study shows that people who suffered from CP are at an increased risk of developing dementia, regardless of gender, age, and dementia and CP subtypes.

Is headache a risk factor for dementia? A systematic review and meta-analysis

OBJECTIVE

In this systematic review and meta-analysis, we critically evaluate available evidence regarding the association between primary headaches and subsequent decline of cognitive function and dementia.

BACKGROUND

Recent studies suggested that headache disorders may increase the risk for dementia. However, available studies are conflicting.

METHODS

To identify qualifying studies, we searched scientific databases, including Pubmed, Scopus, Web of Science, Science Direct and BMC, screening for relevant papers. In order to reduce the heterogeneity between different studies, the analyses were further subdivided according to the clinical diagnoses and the study methodologies.

RESULTS

We identified 23 studies investigating the association between primary headaches and the risk of dementia. Of these, 18 met our inclusion criteria for meta-analysis (covering 924.140 individuals). Overall effect-size shows that primary headaches were associated with a small increase in dementia risk (OR = 1,15; CI 95%: 1,03-1,28; p = 0,02). Analyzing subgroups, we found that migraine was associated with both a moderate increased risk of all-cause dementia (OR = 1,26; p = 0,00; 95% CI: 1,13-1,40) as well as a moderate increased risk of Alzheimer's disease (OR = 2,00; p = 0,00; 95% CI: 1,46-2,75). This association was significant in both case-control and retrospective cohort studies but not in prospective studies.

CONCLUSIONS

Our study supports the presence of a link between primary headaches and dementia. However, in the subgroup analysis, only patients with migraine showed a moderate increase risk for all-cause dementia and for Alzheimer's disease. Additional rigorous studies are needed to elucidate the possible role of primary headaches on the risk of developing cognitive impairment and dementia.

Different Aspects of Aging in Migraine

Migraine is a common neurological disease displaying an unusual dependence on age. For most patients, the peak intensity of migraine headaches occurs in 20s and lasts until 40s, but then headache attacks become less intense, occur less frequently and the disease is more responsive to therapy. This relationship is valid in both females and males, although the prevalence of migraine in the former is 2-4 times greater than the latter. Recent concepts present migraine not only as a pathological event, but rather as a part of evolutionary adaptive response to protect organism against consequences of stress-induced brain energy deficit. However, these concepts do not fully explain that unusual dependence of migraine prevalence on age. Many aspects of aging, both molecular/cellular and social/cognitive, are interwound in migraine pathogenesis, but they neither explain why only some persons are affected by migraine, nor suggest any causal relationship. In this narrative/hypothesis review we present information on associations of migraine with chronological aging, brain aging, cellular senescence, stem cell exhaustion as well as social, cognitive, epigenetic, and metabolic aging. We also underline the role of oxidative stress in these associations. We hypothesize that migraine affects only individuals who have inborn, genetic/epigenetic, or acquired (traumas, shocks or complexes) migraine predispositions. These predispositions weakly depend on age and affected individuals are more prone to migraine triggers than others. Although the triggers can be related to many aspects of aging, social aging may play a particularly important role as the prevalence of its associated stress has a similar age-dependence as the prevalence of migraine. Moreover, social aging was shown to be associated with oxidative stress, important in many aspects of aging. In perspective, molecular mechanisms underlying social aging should be further explored and related to migraine with a closer association with migraine predisposition and difference in prevalence by sex.

Effect of genetic liability to migraine and its subtypes on breast cancer: a mendelian randomization study

BACKGROUND

The relationship between migraine and breast cancer risk has generated conflicting findings. We attempted to assess the association between migraine and breast cancer risk using Mendelian randomization (MR) analysis.

METHODS

We selected genetic instruments associated with migraine from a recently published genome-wide association studies (GWAS). Inverse variant weighted (IVW) analysis was adopted as the main method, and we also performed the weighted-median method and the MR‒Egger, MR pleiotropy residual sum and outlier (MR-PRESSO), and MR Robust Adjusted Profile Score (MR-RAPS) methods as supplements.

RESULTS

Our MR suggested that any migraine (AM) was a risk factor for overall breast cancer (IVW: odds ratio (OR) = 1.072, 95% confidence intervals (CI) = 1.035-1.110, P = 8.78 × 10- 5, false discovery rate (FDR) = 7.36 × 10- 4) and estrogen receptor-positive (ER+) breast cancer (IVW: OR = 1.066, 95% CI = 1.023-1.111, P = 0.0024; FDR = 0.0108) but not estrogen receptor-negative (ER-) breast cancer. In its subtype analysis, women with a history of migraine without aura (MO) had an increased risk of ER- breast cancer (IVW: OR = 1.089, 95% CI = 1.019-1.163, P = 0.0118, FDR = 0.0354), and MO was suggestively associated with the risk of overall breast cancer (FDR > 0.05 and IVW P < 0.05). No significant heterogeneity or horizontal pleiotropy was found in the sensitivity analysis.

CONCLUSION

This study suggested that women with AM have an increased risk of overall breast cancer and ER + breast cancer. MO was suggestively associated with the risk of overall breast cancer and ER- breast cancer.

Association between migraine and Alzheimer's disease: a nationwide cohort study

Background and objective

Migraine is a common chronic neurological disease characterized by pulsating headaches, photophobia, phonophobia, nausea, and vomiting. The prevalence of dementia in individuals aged over 65 years in Korea is more than 10%, and Alzheimer's disease (AD) dementia accounts for most cases. Although these two neurological diseases account for a large portion of the medical burden in Korea, few studies have examined the relationship between the two diseases. Therefore, this study investigated the incidence and risk of AD in patients with migraines.

Methods

We retrospectively collected nationwide data from a national health insurance claims database governed by Korea's National Health Insurance Service. Among Koreans in the 2009 record, patients with migraine were identified according to the International Classification of Diseases, 10th revision (ICD-10) code G43. First, we screened the database for participants aged over 40 years. Individuals diagnosed with migraine at least twice over more than 3 months in a year were considered to have chronic migraine in this study. Further, all participants with an AD diagnosis (ICD-10 code: Alzheimer's disease F00, G30) were investigated for AD dementia development. The primary endpoint was AD development.

Results

The overall incidence of AD dementia was higher in individuals with a history of migraine than in those with no migraine history (8.0 per 1,000 person-years vs. 4.1 per 1,000 person-years). The risk of AD dementia was higher in individuals diagnosed with migraine (hazard ratio = 1.37 [95% confidence interval, 1.35-1.39]) than in the control group after adjustments for age and sex. Individuals with chronic migraine had a higher incidence of AD dementia than those with episodic migraine. Younger age (<65 years old) was associated with an increased risk of AD dementia compared to older age (≥65  years old). Higher body mass index (BMI) (≥25 kg/m²) was also associated with an increased risk of AD dementia compared to lower BMI (<25 kg/m²) (p < 0.001).

Conclusion

Our results suggest that individuals with a migraine history are more susceptible to AD than those without a migraine history. Additionally, these associations were more significant in younger and obese individuals with migraine than in individuals without migraine.

Multiple Chemical Sensitivity: It's time to catch up to the science

Multiple chemical sensitivity (MCS) is a complex medical condition associated with low dose chemical exposures. MCS is characterized by diverse features and common comorbidities, including fibromyalgia, cough hypersensitivity, asthma, and migraine, and stress/anxiety, with which the syndrome shares numerous neurobiological processes and altered functioning within diverse brain regions. Predictive factors linked to MCS comprise genetic influences, gene-environment interactions, oxidative stress, systemic inflammation, cell dysfunction, and psychosocial influences. The development of MCS may be attributed to the sensitization of transient receptor potential (TRP) receptors, notably TRPV1 and TRPA1. Capsaicin inhalation challenge studies demonstrated that TRPV1 sensitization is manifested in MCS, and functional brain imaging studies revealed that TRPV1 and TRPA1 agonists promote brain-region specific neuronal variations. Unfortunately, MCS has often been inappropriately viewed as stemming exclusively from psychological disturbances, which has fostered patients being stigmatized and ostracized, and often being denied accommodation for their disability. Evidence-based education is essential to provide appropriate support and advocacy. Greater recognition of receptor-mediated biological mechanisms should be incorporated in laws, and regulation of environmental exposures.

Contribution of pain to subsequent cognitive decline or dementia: A systematic review and meta-analysis of cohort studies

BACKGROUND

Dementia is an urgent public health problem worldwide, and the determination of the contribution of pain to cognitive decline or dementia is significant for the prevention of dementia.

OBJECTIVE

To comprehensively explore the contribution of pain to subsequent cognitive decline or dementia and analyze possible influencing factors.

DESIGN

Systematic review and meta-analysis of cohort studies.

METHODS

We systematically searched MEDLINE, EMBASE, PsycINFO, CINAHL, Cochrane Library, China National Knowledge Internet, WANFANG DATA and VIP for cohort studies from database inception to January 21, 2022. Random-effects meta-analysis was used to pool odds ratios (ORs) and 95% confidence intervals (CIs) of incident cognitive decline or dementia among patients with pain. Subgroup analyses and meta-regression were used to explore the sources of heterogeneity.

RESULTS

A total of 35 cohort studies containing 1,122,503 participants were included. As a whole, pain (OR = 1.24; 95% CI = 1.17-1.31) was a risk factor for subsequent cognitive decline or dementia; headache, migraine, tension-type headache, widespread pain, and irritable bowel syndrome, but not burning mouth syndrome, were also risk factors. Pain increased the risk of all-cause dementia (OR = 1.26; 95% CI = 1.18-1.35), Alzheimer's disease (OR = 1.28; 95% CI = 1.12-1.47), and vascular dementia (OR = 1.31; 95% CI = 1.06-1.62). Pain interference (OR = 1.42; 95% CI = 1.16-1.74) was associated with an increased risk of cognitive decline or dementia, while pain intensity was not. Pooled results from studies with sample sizes less than 2000 or with relatively low quality showed that pain did not increase the risk of cognitive decline or dementia. There was no statistically significant increase in the risk of cognitive decline or dementia in people with pain aged ≥75 years.

CONCLUSIONS

Our results demonstrated that pain increased the risk of subsequent cognitive decline or dementia. Sample size, study methodological quality, types of pain, pain severity (pain interference), and age composition of the study population may affect the relationship between pain and cognitive decline or dementia.

REGISTRATION

PROSPERO (CRD42022316406).

The association between migraine and dementia - a national register-based matched cohort study

OBJECTIVES

Migraine and dementia, two major public health challenges, are associated, but more knowledge is needed to understand their relationship. Objectives of this study were to investigate 1) the association between non-self-reported measures of migraine and dementia, and whether dementia was associated with 2) migraine without aura (MO) and with aura (MA) in combination with migraine medication use, and 3) migraine severity operationalized as the number of migraine prescriptions.

STUDY DESIGN

Matched cohort study.

METHODS

National register data were obtained from individuals born between 1934 and 1958. Migraine cases (aged 25-58 years) were identified by migraine diagnoses and redeemed migraine medication. Migraine cases were matched with non-cases (N = 340,850) and date of diagnosis or medication redemption was defined as index year. Dementia was identified by dementia diagnoses and redeemed dementia medication.

RESULTS

We observed a 1.46 (95% CI: 1.26-1.69) times higher dementia rate in individuals with a migraine diagnosis and a 0.86 (95% CI: 0.76-0.97) times lower rate when using migraine medication. We found the highest dementia rate among individuals with MA, who also used migraine medication (HR = 2.23; 95% CI: 1.19-4.17), and the lowest rate among individuals with MO, who also used medication (HR = 1.25; 95% CI: 0.75-2.10). The number of migraine medication prescriptions was not associated with dementia.

CONCLUSIONS

Being registered with a migraine diagnosis was associated with a higher dementia rate, while use of prescribed migraine medication was not. The differences in the dementia rate among migraine cases identified via diagnoses versus medications warrants further investigation.

Increased risk of all-cause, Alzheimer's, and vascular dementia in adults with migraine in Korea: a population-based cohort study

BACKGROUND

Studies investigating the association between migraine and dementia have reported inconsistent findings. This study aimed to evaluate whether patients with migraine have an increased risk of dementia compared to individuals without migraine.

METHODS

We obtained data from the 2002-2019 Korean National Health Insurance Health Screening Cohort. Non-migraine controls were selected using a 1:1 risk-set matching with a time-dependent propensity score. The main outcome was the development of all-cause dementia, and the secondary outcome was the development of each cause of dementia (Alzheimer's, vascular, mixed or other specified, and unspecified dementia). The incidence rate of dementia was calculated using Poisson regression, and the association between migraine and dementia was evaluated using Cox proportional hazards regression.

RESULTS

Among 88,390 participants, 66.1% were female, and the mean baseline age was 55.3 ± 9.4 years. During the study period, dementia cases were identified in 4,800 of the 44,195 patients with migraine and 3,757 of the 44,915 matched controls. The incidence rate of dementia was 139.6 (95% confidence interval [CI], 135.7-143.5) and 107.7 (95% CI, 104.3-111.1) cases per 10,000 person-years in patients with migraine and matched controls, respectively. Patients with migraine had a 1.30 (hazard ratio [HR], 1.30; 95% CI, 1.25-1.35), 1.29 (HR, 1.29; 95% CI, 1.23-1.35), 1.35 (HR, 1.35; 95% CI, 1.19-1.54), 1.36 (HR, 1.36; 95% CI, 1.00-1.83), and 1.30 (HR, 1.30; 95% CI, 1.17-1.45) times higher risk of developing all-cause dementia, Alzheimer's dementia, vascular dementia, mixed or other specified dementias, and unspecified dementia than their matched controls, respectively.

CONCLUSION

Our results suggest that migraine is associated with an increased risk of subsequent dementia. Further research is warranted to confirm these findings and to reveal the underlying mechanisms.

Primary headaches increase the risk of dementias: An 8-year nationwide cohort study

Background

Headache, a highly prevalent neurological disorder, has consistently been linked with an elevated risk of dementia. However, most studies are focused on the relationship with migraine in limited age groups. Therefore, the objective of this research was to look at the link between various type of headaches and dementias based on longitudinal population-based data.

Methods and results

Participants diagnosed with headache from 2002 to 2005 were selected and major covariates were collected. The diagnoses of Alzheimer’s disease, vascular dementia, and other dementias were observed from 2006 until 2013. The adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) of dementias according to headache type were calculated by Cox proportional hazards regression. A number of 470,652 participants were observed for a mean of 7.6 years (standard deviation: 1.2), for approximately 3.6 million person-years. Both tension type headache (TTH) and migraine elevated the risk of all-cause dementias (TTH, aHR 1.18, 95% CI 1.13–2.24; migraine, aHR 1.18, 95% CI 1.13–2.24). Headaches had a greater influence in females and non-smokers as a risk factor of dementias. Patients with migraine who consumed alcohol had a higher risk of dementia, however this was not true with TTH patients. Among participants without comorbidities, TTH patients were more susceptible to dementia than migraine patients. Headache patients had a higher proportion of females regardless of headache type and approximately 1.5 times more individuals had three or more comorbidities compared to those without headache.

Conclusions

Headache could be an independent predictor for subsequent dementia risk. Future studies should focus on clarifying pathogenic pathways and possible dementia-related preventive measures in headache populations.

Association between migraine and cognitive impairment

Background

Previous studies revealed inconsistent results regarding association between migraine and cognitive impairment. In addition, previous studies found inconsistent results regarding the association between migraine and risk of dementia. Thus, the study aimed to make a meta-analysis exploring comparison result in different types of cognitive function between migraine patients and non-migraine subjects. In addition, meta-analysis was made to explore the association between migraine and risk of dementia.

Methods

Articles published before June 2022 were searched in the following databases: PubMed, Web of Science, SCOPUS, EMBASE, EBSCO, PROQUEST, ScienceDirect and Cochrane Database of Systematic Reviews. Results were computed using STATA 12.0 software.

Results

Meta-analysis showed lower general cognitive function and language function in migraine group, compared to no migraine group (general cognitive function: standard mean difference (SMD) = − 0.40, 95% CI = − 0.66 to − 0.15; language: SMD = − 0.14, 95% confidence interval (CI) = − 0.27 to − 0.00), whereas the study showed no significant difference in visuospatial function, attention, executive function and memory between migraine group and no migraine group (visuospatial function: SMD = − 0.23, 95% CI = − 0.53 to 0.08; attention: SMD = − 0.01, 95% CI = − 0.10 to 0.08; executive function: SMD = − 0.05, 95% CI = − 0.16 to 0.05; memory: SMD = − 0.14, 95% CI = − 0.30 to 0.03). In addition, the meta-analysis showed a significant association between migraine and risk of dementia (odds ratio (OR)/relative risk (RR) = 1.30, 95% CI = 1.11 to 1.52).

Conclusions

In conclusion, the meta-analysis demonstrated lower general cognitive function and language function in migraine. In addition, migraine is associated with an increased risk of all-cause dementia, VaD and AD. These results suggest a significant association between migraine and cognitive impairment. Because of the association between migraine and cognitive impairment, neurological physician should be vigilant and effectively intervene in migraineurs with high risk factors of cognitive impairment to prevent the development of cognitive impairment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10194-022-01462-4.

Migraine and the risk of dementia: a meta-analysis and systematic review

OBJECTIVES

To conduct a comprehensive systematic review and meta-analysis to explore the correlation between migraine and the risk of dementia.

METHODS

The PubMed, EMBASE, and Cochrane library databases were searched systematically. We selected cohort studies (prospective and retrospective) and case-control studies that reported migraine in patients with dementia, including vascular dementia. The pooled effects were analyzed to evaluate relative risk with 95% confidence intervals.

RESULTS

In total, nine studies (two case-control and seven cohort studies) including 291,549 individuals were identified. These studies indicated that people with migraine (relative risk = 1.33; 95% confidence interval: 1.16-1.53) have an increased risk of all-cause dementia. Additionally, the pooled results of four studies showed that migraine is associated with an increased risk of vascular dementia (relative risk = 1.85; 95% confidence interval: 1.22-2.81; P = 0.004).

CONCLUSIONS

Data from observational studies suggest that migraine may be a risk factor for dementia, particularly vascular dementia. More studies are warranted to explore the association between migraine and dementia and the potential common pathophysiological mechanisms.

Migraine, Brain Glucose Metabolism and the "Neuroenergetic" Hypothesis: A Scoping Review

Increasing evidence suggests that migraine may be the result of an impaired brain glucose metabolism. Several studies have reported brain mitochondrial dysfunction, impaired brain glucose metabolism and gray matter volume reduction in specific brain areas of migraineurs. Furthermore, peripheral insulin resistance, a condition demonstrated in several studies, may extend to the brain, leading to brain insulin resistance. This condition has been proven to downregulate insulin receptors, both in astrocytes and neurons, triggering a reduction in glucose uptake and glycogen synthesis, mainly during high metabolic demand. This scoping review examines the clinical, epidemiologic and pathophysiologic data supporting the hypothesis that abnormalities in brain glucose metabolism may generate a mismatch between the brain's energy reserve and metabolic expenditure, triggering migraine attacks. Moreover, alteration in glucose homeostasis could generate a chronic brain energy deficit promoting migraine chronification. Lastly, insulin resistance may link migraine with its comorbidities, like obesity, depression, cognitive impairment and cerebrovascular diseases. PERSPECTIVE: Although additional experimental studies are needed to support this novel "neuroenergetic" hypothesis, brain insulin resistance in migraineurs may unravel the pathophysiological mechanisms of the disease, explaining the migraine chronification and connecting migraine with comorbidities. Therefore, this hypothesis could elucidate novel potential approaches for migraine treatment.

Association of Headache Disorders and the Risk of Dementia: Meta-Analysis of Cohort Studies

Objectives

The purpose of this meta-analysis is to assess whether there is an association between headache disorders and all-cause dementia, Alzheimer's disease (AD), and vascular dementia (VaD).

Methods

PubMed, Cochrane Library, Embase, and Web of Science were searched for cohort studies published from database inception to October 8, 2021, using medical subject headings (MeSH) and keywords. All statistical analyses were performed using Stata statistical software version 14.0. If P > 0.1 and I² ≤ 50%, a fixed-effects model was adopted. If I² > 50% (which indicated great heterogeneity), a random-effects model was adopted. The funnel plot and Egger's test were used to evaluate publication bias.

Results

This meta-analysis included 12 cohort studies covering 465,358 individuals, which were published between 2001 and 2020. The pooling analysis shows that a history of any headache disorder is associated with an increased risk of all-cause dementia (OR = 1.35; 95% CI: 1.21–1.50; I² = 81.6%, P < 0.001). The history of any headache was associated with an increased risk of AD (OR = 1.49; 95% CI: 1.08–2.05; I² = 70.0%, P = 0.003) and VaD (OR = 1.72; 95% CI: 1.32–2.25; I² = 0%, P < 0.001). In the subgroup analysis, females with a history of headache have a slightly higher risk of dementia than males (OR = 1.32; 95% CI: 1.16–1.51; I² = 88.3%, P < 0.001) and the risk of dementia in the retrospective cohort was slightly higher than in the prospective cohort (OR = 1.38; 95% CI: 1.22–1.56; I² = 83.4%, P < 0.001).

Conclusions

Our meta-analysis shows that any headache disorder increases the risk of all-cause dementia, AD, or VaD. These findings provide evidence that headache should be recognized as an independent risk factor for dementia, AD, or VaD.

Acupuncture Treatment is Associated with Reduced Dementia Risk in Patients with Migraine: A Propensity-Score-Matched Cohort Study of Real-World Data

BACKGROUND

Migraine is a recurrent headache disease that has been identified as a risk factor for subsequent dementia. The present study collected data from Taiwan's National Health Insurance Research Database (NHIRD) to investigate the incidence of dementia in patients with migraine who did or did not concurrently receive acupuncture treatment.

METHODS

A 1:1 propensity score method was used to match an equal number of patients (N = 4813) in the acupuncture and nonacupuncture cohorts based on sex, age, migraine diagnosis year, index year, insurance amount, urbanization level, baseline comorbidities, and medication usage. We employed Cox proportional hazards models to evaluate the risk of dementia.

RESULTS

Patients with migraine who received acupuncture treatment were found to have a lower risk of dementia (adjusted hazard ratio [aHR] = 0.51, 95% CI = 0.40-0.65) than those who did not undergo acupuncture treatment. The cumulative incidence of dementia was significantly lower in the acupuncture cohort than in the nonacupuncture cohort (Log rank test, p < 0.001). This propensity score-matched cohort study demonstrated an association between acupuncture treatment and dementia development in patients with migraine in Taiwan.

CONCLUSION

The results suggest that acupuncture treatment significantly reduced the development of dementia in patients with migraine.

Meta-analysis of association between migraine and risk of dementia

OBJECTIVES

The association between migraine and dementia has rarely been investigated, and available results are conflicting. Thus, the aim of this meta-analysis was to evaluate whether an association exists between migraine and dementia.

MATERIALS & METHODS

We searched for cohort studies from databases including PubMed, EBSCO, Web of Science, and EMBASE database from inception to April 1, 2021, using subject and free words. RevMan 5.1 software was used to calculate the risk ratio (RR) of dementia in patients with migraine. Subgroup and sensitivity analyses were conducted to assess the source of heterogeneity. A random-effects model was used when heterogeneity was present. The Funnel plot and Egger's test were used to evaluate publication bias.

RESULTS

Five published cohort studies covering a total of 249,303 individuals were identified. Pooled analysis showed that migraine was associated with increased risk of all-cause dementia (RR: 1.34, 95% CI: 1.13-1.59) and Alzheimer's disease (AD) (RR: 2.49, 95% CI: 1.16-5.32). However, we did not found any association between migraine and risk of vascular dementia (VaD) (RR: 1.51, 95% CI: 0.77-2.96).

CONCLUSIONS

Our results revealed that migraine was a potential risk indicator for AD and all-cause dementia.

Frailty and the risk of dementia: is the association explained by shared environmental and genetic factors?

BACKGROUND

Frailty has been identified as a risk factor for cognitive impairment and dementia. However, it is not known whether familial factors, such as genetics and shared environmental factors, underlie this association. We analyzed the association between frailty and the risk of dementia in a large twin cohort and examined the role of familial factors in the association.

METHODS

The Rockwood frailty index (FI) based on 44 health deficits was used to assess frailty. The population-level association between FI and the risk of all-cause dementia was analyzed in 41,550 participants of the Screening Across the Lifespan Twin (SALT) study (full sample, aged 41-97 years at baseline), using Cox and competing risk models. A subsample of 10,487 SALT participants aged 65 and older who received a cognitive assessment (cognitive sample) was used in a sensitivity analysis to assess the effect of baseline cognitive level on the FI-dementia association. To analyze the influence of familial effects on the FI-dementia association, a within-pair analysis was performed. The within-pair model was also used to assess whether the risk conferred by frailty varies by age at FI assessment.

RESULTS

A total of 3183 individuals were diagnosed with dementia during the 19-year follow-up. A 10% increase in FI was associated with an increased risk of dementia (hazard ratio [HR] 1.17 (95% confidence interval [CI] 1.07, 1.18)) in the full sample adjusted for age, sex, education, and tobacco use. A significant association was likewise found in the cognitive sample, with an HR of 1.13 (95% CI 1.09, 1.20), adjusted for age, sex, and cognitive level at baseline. The associations were not attenuated when adjusted for APOE ɛ4 carrier status or considering the competing risk of death. After adjusting for familial effects, we found no evidence for statistically significant attenuation of the effect. The risk conferred by higher FI on dementia was constant after age 50 until very old age.

CONCLUSIONS

A higher level of frailty predicts the risk of dementia and the association appears independent of familial factors. Targeting frailty might thus contribute to preventing or delaying dementia.

Mid- and Late-Life Migraine Is Associated with an Increased Risk of All-Cause Dementia and Alzheimer's Disease, but Not Vascular Dementia: A Nationwide Retrospective Cohort Study

We used a nationwide cohort sample of data from 2002 to 2013, representing approximately 1 million patients to investigate the prospective association between migraine and dementia. The migraine group (n = 1472) included patients diagnosed between 2002 and 2004, aged over 55 years; the comparison group was selected using propensity score matching (n = 5888). Cox proportional hazards regression analyses was used to calculate the hazard ratios (HRs). The incidence of dementia was 13.5 per 1000 person-years in the migraine group. Following adjustment for sociodemographic and comorbidities variables, patients with migraine developed dementia more frequently than those in the comparison group (adjusted HR = 1.37, 95% confidence interval [CI], 1.16–1.61). In the subgroup analysis, we found a higher HR of dementia events in male, the presence of comorbidities, and older age (≥65) patients with migraine, compared to those without migraine. Moreover, patients with migraine had a significantly higher incidence of Alzheimer’s disease (adjusted HR = 1.31, 95% CI, 1.08–1.58), but not vascular dementia, than those without migraine. Therefore, our findings suggest that mid- and late-life migraines may be associated with an increased incidence of all-cause dementia and Alzheimer’s disease, but not vascular dementia.

Towards a Consensus on Alzheimer's Disease Comorbidity?

Alzheimer's disease (AD) is often comorbid with other pathologies. First, we review shortly the diseases most associated with AD in the clinic. Then we query PubMed citations for the co-occurrence of AD with other diseases, using a list of 400 common pathologies. Significantly, AD is found to be associated with schizophrenia and psychosis, sleep insomnia and apnea, type 2 diabetes, atherosclerosis, hypertension, cardiovascular diseases, obesity, fibrillation, osteoporosis, arthritis, glaucoma, metabolic syndrome, pain, herpes, HIV, alcoholism, heart failure, migraine, pneumonia, dyslipidemia, COPD and asthma, hearing loss, and tobacco smoking. Trivially, AD is also found to be associated with several neurodegenerative diseases, which are disregarded. Notably, our predicted results are consistent with the previously published clinical data and correlate nicely with individual publications. Our results emphasize risk factors and promulgate diseases often associated with AD. Interestingly, the comorbid diseases are often degenerative diseases exacerbated by reactive oxygen species, thus underlining the potential role of antioxidants in the treatment of AD and comorbid diseases.

Headache - A Window to Dementia: An Unexpected Twist

Migraine and other types of headaches have several symptoms associated with them. The association between migraine and dementia has been considered. It is a topic of discussion and appears to be multifactorial. Dementia is a cluster of symptoms, with memory loss and cognitive dysfunction being the prominent symptoms. In this review, we discussed the association of headache and cognitive dysfunction in a broader context and how the practiced treatment of headaches may silently lead to dementia. We conducted a thorough literature search using PubMed as our main database. The articles exploring the association between headache (both migraine and non-migraine) and dementia were included. Some risk factors like migraine-induced stroke and inherent vascular diseases in migraine patients channeling to stroke and dementia were not considered. A total of 28 studies were included for review. All the reviewed studies put together showed an association between headache and cognitive dysfunction of any form. They showed that the frequency and duration of headache is a determinant for dementia. Few studies also focused on how treating headaches with certain drugs can lead to dementia. The reviewed published literature showed that headaches of any sort and their treatment are potentially linked to dementia. Not all headache patients will require medical treatment, as the benefit might outweigh the risk sometimes. It is interim to understand these facts and formulate a better protocol for treating headache patients. However, due to some discordant results, further studies are needed.