A nationwide Korean study finds a surprising link between varicose veins and dementia, and suggests that treating the veins could help prevent vascular brain damage.
Study: Association between varicose veins and the occurrence of dementia: A nationwide population-based cohort study. Image Credit: New Africa / Shutterstock.com
A recent PLOS One study explores the association between the development of dementia and the presence of varicose veins (VV).
Varicose veins and dementia
The global prevalence of VV currently ranges from 2% to 73%, depending on geographic location and study methodologies. VV is characterized by twisted, enlarged, and superficial veins with a diameter of three millimeters (mm) or more.
Some factors that may contribute to the development of VV include aging, obesity, female sex, and chronic constipation. In fact, some of the vascular changes that are shared between VV and aging have also been associated with neurodegenerative diseases and cognitive impairment.
Previous studies have reported that VV, venous hypertension, and valvular reflux are correlated with white matter changes in the brain. Venous pathology could reduce cerebral venous drainage, thereby aggravating known risk factors for dementia, such as worsening white matter lesions and cerebral small vessel disease.
Dementia is defined as persistent and progressive cognitive decline, memory loss, and behavioral changes, with Alzheimer’s disease (AD) or vascular dementia (VD) responsible for most dementia cases. Researchers predict that, due to the rapidly aging global population, the prevalence of dementia will significantly rise throughout the world.
Although the exact causes of dementia remain unclear, vascular damage and damage to target organs resulting from venous issues contribute to the development of dementia. However, additional mechanistic studies must be conducted to explore this potential association further.
About the study
The researchers of the current longitudinal study used population data to determine the relationship between VV and the risk of developing dementia, as well as the role of VV treatment in mitigating this association.
Data were obtained from South Korea’s National Health Insurance Service-Health Screening (NHIS-HEALS) cohort database between 2002 and 2019. These data are obtained from adults 40 and older who underwent a free health screening twice yearly.
The current analysis included 430,875 individuals who underwent health screening between 2005 and 2010. Individuals with a history of all-cause dementia and those with incomplete data were excluded. The final sample comprised 396,767 individuals, 1.3% of whom had a history of VV.
Propensity score matching (PSM) was conducted to ensure balanced comparison.
The primary study outcome was all-cause dementia, whereas secondary outcomes included the occurrence of AD and VD. Diagnoses required two or more medical claims along with antidementia drug prescriptions, improving diagnostic accuracy. Data on other covariates such as age, sex, income, and physical activity levels were also considered for the analysis.
Study findings
The average age of the study cohort was 56 years, 46% of whom were male. As compared to individuals diagnosed with VV, smoking, alcohol consumption, and a history of diabetes mellitus were more prevalent in those without a history of VV. However, the frequency of comorbidities was higher in the VV group.
During a median follow-up period of 13.3 years, 13.9%, 9.7%, and 3.7% of individuals were diagnosed with all-cause dementia, AD, and VD, respectively. In the multivariate analysis, individuals with VV were at an increased risk of all-cause dementia.
VV did not correlate with AD or VD risk in multivariate models; however, the association between all-cause dementia and VV was consistently observed in the post-PSM sensitivity analysis, regardless of covariates. Notably, men, current smokers, and heavy drinkers with VV had a significantly higher risk of developing all-cause dementia.
The incidence risk of all-cause dementia was not significantly different between patients diagnosed with VV who did or did not receive treatments for their VV. The treatment/procedure of VV was associated with a lower risk of AD before PSM, but not after PSM. A significant association between lower VD risk and the treatment/procedure of VV was observed before and after PSM.
Conclusions
The study findings suggest that VV is associated with an increased risk of all-cause dementia, with the treatment/procedure of VV potentially reducing the incidence risk of VD. However, these associations do not imply causality due to the retrospective observational design.
A key limitation of the current study is the categorization and severity of VV, which cannot be deduced from health data. Additionally, unmeasured confounding factors like a family history of dementia and different levels of urbanization could potentially influence the outcomes.
Importantly, the dataset used for the analysis was not representative of the entire South Korean population, as it included a random sampling of 10% of all South Koreans. Moreover, since the cohort includes only individuals aged 40 and older, findings may not generalize to younger populations.