Do Varicose Veins Raise the Risk of Alzheimer's? What Three Recent Cohort Studies Found — and What They Cannot Show

Varicose veins are generally treated as a problem of the legs — heaviness, aching, appearance. Over the past few years, however, a series of population studies has reported something less expected: an association between varicose veins and the later development of dementia, including Alzheimer's disease.

The finding deserves attention. It also deserves to be read precisely, because the gap between "associated with" and "causes" is where most of the misunderstanding lives. Below are the three main studies, what each actually measured, and where the evidence stops.

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Study 1 — Taiwan, 2022: Alzheimer's incidence 1.6 times higher

The study that started the discussion was published by Cheng in the Journal of Prevention of Alzheimer's Disease in 2022. Using the Chang Gung Research Database, it enrolled 9,601 patients aged 45 or over with varicose veins and 38,404 controls matched for sex, age and index date, with follow-up to the end of 2017.

The incidence of Alzheimer's disease was 12.60 per 10,000 person-years in the varicose vein group against 6.24 in controls — a hazard ratio of 1.647 (95% CI 1.326–2.045, P < 0.001). Patients with complicated varicose veins — skin changes, ulceration, thrombophlebitis — had higher incidence still than those with uncomplicated disease (adjusted HR 1.474).

Two things to notice. The relative risk is meaningful but modest — not a doubling. And the absolute rate is low: roughly one case per 800 patients per year in the varicose vein group.

Study 2 — Korea, 2025: all-cause dementia, and a hint about treatment

Woo and colleagues, in PLoS One in 2025, used the Korean national health screening cohort — 430,875 participants, median follow-up 13.3 years. Varicose veins were present in 5,096 (1.3%). Over follow-up, 55,329 participants (13.9%) developed dementia of any cause.

After propensity matching and multivariable adjustment, varicose veins were associated with a 23.5% increase in all-cause dementia (HR 1.235, 95% CI 1.147–1.329). The effect was smaller than in the Taiwanese study, and — importantly — this study also looked at whether treating the varicose veins made any difference. It did for vascular dementia: treated patients had roughly half the risk of vascular dementia (HR 0.566, 95% CI 0.382–0.841). It did not for Alzheimer's disease.

That split is informative. Vascular dementia is, by definition, caused by cerebrovascular disease; a link with a systemic vascular condition, and a benefit from treating it, is plausible. Alzheimer's disease is a different pathology, and the treatment signal was absent.

Study 3 — China, 2025: the biochemistry, before dementia

The third study asks a sharper question. If varicose veins are linked to Alzheimer's, is there any sign of Alzheimer's pathology in people with varicose veins who do not yet have dementia?

Liu and colleagues (Frontiers in Aging Neuroscience, 2025) examined 1,298 non-demented adults in the Chinese Alzheimer's Biomarker and LifestylE (CABLE) study, who had cerebrospinal fluid analysed for the core Alzheimer's biomarkers. After adjusting for age, sex, education and APOE-ε4 status, varicose veins were associated with lower CSF Aβ42 (β = −0.157), a lower Aβ42/Aβ40 ratio (β = −0.272), and higher phosphorylated tau (β = 0.192) — the direction that indicates more amyloid deposition in the brain and more tau pathology. The associations were stronger in women, in mid-life adults (40–65), and in APOE-ε4 non-carriers.

This does not prove causation either, but it moves the finding from diagnostic codes in a claims database to measured brain chemistry in people without symptoms.

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Why might a leg vein be connected to the brain?

The honest answer is that nobody knows, and the studies above do not test any mechanism. Several hypotheses are in circulation; they should be read as hypotheses.

Shared vascular biology. Varicose veins are increasingly understood as one expression of a systemic vascular disorder rather than a local defect — with endothelial dysfunction, chronic low-grade inflammation and oxidative stress as common threads. A 2026 review by Campello and colleagues describes an "arterial-venous continuum" in which atherosclerosis and chronic venous disease share these mechanisms; it notes the dementia associations explicitly, and equally explicitly states that they are observational and do not establish causality. We have written about the inflammatory dimension of venous disease separately.

Chronic inflammation. Sustained inflammatory signalling is implicated in amyloid and tau pathology. Whether the inflammation of venous disease is of the kind, or the magnitude, to affect the brain is not known.

Endothelial and blood–brain barrier dysfunction. A dysfunctional endothelium is a feature of venous disease; a leaky blood–brain barrier is a feature of Alzheimer's. The two have not been linked in the same patients.

Venous congestion and brain clearance. The glymphatic system clears metabolic waste from the brain, largely during sleep, and depends on healthy venous outflow. Whether systemic venous dysfunction affects it is a hypothesis without direct evidence.

What the studies cannot show

All three are observational. They demonstrate association, not causation, and there are at least three alternative explanations that none of them can exclude:

• Shared risk factors. Age, obesity, physical inactivity and cardiovascular disease raise the risk of both varicose veins and dementia. Adjustment helps but cannot fully remove this.
• Detection bias. People who see doctors for varicose veins are examined more often and may have dementia diagnosed earlier.
• Reverse causation is unlikely for varicose veins, but residual confounding by overall vascular health is very likely.

The Korean study's finding that treatment reduced vascular dementia but not Alzheimer's is consistent with varicose veins being a marker of vascular risk rather than a cause of Alzheimer's pathology. That is the most defensible current reading.

No study has shown that treating varicose veins reduces the risk of Alzheimer's disease. Nothing here is a reason to have a procedure.

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Summary

Evidence	Three cohort studies (Taiwan 2022, Korea 2025, China 2025) plus a CSF biomarker study
Size of effect	Alzheimer's HR 1.65 (Taiwan); all-cause dementia HR 1.24 (Korea) — modest
Absolute risk	About 1 Alzheimer's case per 800 varicose vein patients per year
Treatment effect	Reduced vascular dementia (HR 0.57); no effect on Alzheimer's
Mechanism	Unknown; several hypotheses, none tested
Causation	Not established

What this means for you

Varicose veins should be assessed and, where indicated, treated on their own merits — symptoms, skin changes, and progression. The dementia literature adds one more reason to think of them as a signal about vascular health in general rather than a cosmetic issue, and to take the things that protect both the veins and the brain — walking, weight control, blood pressure — seriously. It does not add a reason to fear a diagnosis of varicose veins, and it does not add an indication for treatment.

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References

• Cheng CY. Increased Incident Alzheimer's Disease among Individuals with Varicose Veins: A Population-Based Cohort Study. J Prev Alzheimers Dis. 2022;9(3):441-448. (PMID: 35841245)
• Woo HG, Park JY, Park MS, Song TJ. Association between varicose veins and occurrence of dementia: A nationwide population-based cohort study. PLoS One. 2025;20(4):e0322892. (PMID: 40305494)
• Liu M, Ma LY, Li QY, et al. Associations of varicose veins with cerebrospinal fluid biomarkers of Alzheimer's disease pathologies in adults without dementia: the CABLE study. Front Aging Neurosci. 2025;17:1502154. (PMID: 40103929)
• Campello E, Boccatonda A, Napolitano A, Simion C, et al. The arterial-venous continuum: bridging atherosclerosis and chronic venous disease through endothelial dysfunction. Intern Emerg Med. 2026;21(5):1531-1542. (PMID: 41954696)
• Castro-Ferreira R, Cardoso R, Leite-Moreira A, Mansilha A. The Role of Endothelial Dysfunction and Inflammation in Chronic Venous Disease. Ann Vasc Surg. 2018;46:380-393. (PMID: 28688874)