Peripheral artery disease in the legs is caused by atherosclerosis, a gradual buildup of fatty deposits, fibrous tissue, and calcium inside the arteries that supply blood to your lower limbs. This process narrows and stiffens the vessels over years, progressively choking off blood flow to the muscles and tissues below the blockage. While a handful of conditions can mimic PAD symptoms, the overwhelming majority of cases trace back to this same arterial plaque buildup, driven by a web of risk factors that range from smoking and diabetes to inflammation, environmental exposures, and even your neighborhood’s income level.
How Arteries Become Blocked
The process starts with damage to the inner lining of an artery. Something irritates or injures the endothelium, the thin layer of cells that keeps the vessel smooth and flexible. Once that lining is disrupted, cholesterol-carrying particles begin to accumulate in the artery wall, triggering a cascade of lipid buildup, fibrous tissue formation, and eventually calcification that narrows the vessel opening.1PubMed Central. Pathophysiology of Atherosclerosis The immune system gets involved early: white blood cells, particularly macrophages and T lymphocytes, flood the developing plaque and release inflammatory signals that promote further growth and instability.2PubMed. Immune mechanisms in atherosclerosis
This is the same disease process that causes heart attacks and strokes when it strikes coronary or brain-feeding arteries. In PAD, the target is most often the arteries of the legs, especially below the knee and in the thigh. Because PAD shares its root mechanism with coronary artery disease, the two conditions frequently coexist, and PAD itself is a strong predictor of future heart attack, stroke, and death from vascular causes.3PubMed. Peripheral arterial disease: Pathophysiology, risk factors, diagnosis, treatment, and prevention
Smoking
If there is one risk factor that dominates PAD more than any other, it is cigarette smoking. Smoking is considered the single most important preventable cause of the disease. Components of cigarette smoke damage the endothelial cells that line arteries, alter the behavior of smooth muscle cells in vessel walls, and push immune cells called macrophages toward a more destructive state.4PubMed Central. Smoking and the Pathophysiology of Peripheral Artery Disease These molecular changes lay the groundwork for plaque formation and accelerate disease once it has started.
Smoking does not just raise the odds of getting PAD. It is also strongly linked to faster disease progression, worse outcomes after surgical or catheter-based procedures, and higher overall healthcare use.5PubMed Central. A modern day perspective on smoking in peripheral artery disease The relationship between smoking and PAD is dose-dependent: the more pack-years of exposure, the greater the risk, and the risk lingers for years after quitting, though it does decline over time. For someone already diagnosed with PAD, stopping smoking is the highest-impact lifestyle change available.
Diabetes
Persistently high blood sugar damages arteries through several overlapping pathways. Chronic hyperglycemia triggers increased oxidative stress, promotes the formation of harmful sugar-protein compounds known as advanced glycation end products, and activates inflammatory gene pathways that injure the vessel wall.6PubMed Central. Diabetes and peripheral artery disease: A review The net effect is that people with diabetes tend to develop PAD earlier, in more vessels, and with heavier calcification than those without diabetes.
Diabetes also complicates PAD in a specific way: it accelerates calcification of the middle layer of the artery wall, a process called medial arterial calcification. When diabetes and chronic kidney disease are both present, plaque calcification, inflammation, and new blood vessel growth inside the plaque are all significantly worse than when either condition exists alone.7PubMed Central. Incremental effects of diabetes mellitus and chronic kidney disease in medial arterial calcification That synergy matters clinically because diabetic PAD patients already face higher amputation rates, and adding kidney dysfunction to the picture amplifies the danger further. In a large insured population, diabetes was among the strongest predictors of critical limb ischemia, the most severe stage of PAD where tissue death threatens the limb.8PubMed. Epidemiology of peripheral arterial disease and critical limb ischemia in an insured national population
Cholesterol and Lipids
High LDL cholesterol has been a recognized driver of atherosclerosis for decades, and PAD is no exception. But not all LDL particles are equally harmful. Research has increasingly pointed to small dense LDL particles as especially dangerous for leg arteries. A large cohort study and meta-analysis found that for every 37 mg/dL increase in small dense LDL cholesterol, the risk of PAD roughly doubled. People in the top ten percent of small dense LDL had about two and a half times the risk of developing PAD compared with those in the lower half.9PubMed. The association between small dense low-density lipoprotein cholesterol and peripheral artery disease: a large-scale cohort study and meta-analysis The same study showed that small dense LDL carried a stronger association with PAD than with heart attack or stroke, suggesting that leg arteries may be particularly vulnerable to this lipid subtype.
High Blood Pressure
Hypertension forces arteries to endure abnormally high mechanical stress with every heartbeat. Over time, this damages the endothelial lining, promotes inflammatory changes, and stiffens vessel walls, all of which speed up plaque development. PAD currently affects roughly eight million people in the United States, and hypertension is recognized as a major contributing risk factor and a key target for reducing PAD complications.10PubMed Central. Hypertension in Patients With Peripheral Artery Disease: An Updated Literature Review The relationship works in both directions: PAD itself can make blood pressure harder to control because stiffened arteries lose their ability to expand and absorb pressure waves.
Inflammation as a Driver
Atherosclerosis is not purely a plumbing problem of fat clogging pipes. It is fundamentally an inflammatory disease, and markers of chronic inflammation have emerged as independent risk factors for PAD, separate from cholesterol or blood pressure. In the large, long-running ARIC study, high-sensitivity C-reactive protein, a widely used blood marker of inflammation, was robustly associated with both PAD and its most severe form, critical limb ischemia, even after accounting for other known risk factors. A fibrosis marker called galectin-3 showed an independent association as well, pointing to the involvement of tissue scarring in how PAD develops.11PubMed Central. Fibrosis and Inflammatory Markers and Long-Term Risk of Peripheral Artery Disease: The ARIC Study
A study of older men put the scale of the inflammatory effect into sharper focus. Men with the highest levels of inflammatory cytokines like interleukin-6 and tumor necrosis factor alpha had roughly four times the odds of having PAD compared with men whose levels were lowest. The effect of high inflammation was similar in magnitude to being ten years older.12PubMed Central. Prevalent peripheral arterial disease and inflammatory burden That comparison is striking because age is one of the strongest known risk factors for PAD, and it suggests chronic inflammation can age your arteries well beyond your calendar years.
Age, Sex, and Genetics
Age is probably the most powerful non-modifiable risk factor. The prevalence of PAD in older populations is high and rises steeply with each decade of life.13PubMed. Peripheral arterial disease in the elderly: The Rotterdam Study Most people diagnosed with symptomatic PAD are over 60, though the disease can begin silently decades earlier.
PAD was long assumed to be primarily a men’s disease. That is outdated. Population studies now show that women are affected at least as often as men, and after the age of 40, more women than men have PAD.14PubMed Central. Peripheral Arterial Disease in Women: an Overview of Risk Factor Profile, Clinical Features, and Outcomes Part of the confusion comes from how PAD presents differently by sex. Women are more likely to have atypical symptoms, which may not fit the textbook picture of calf pain while walking, leading to delayed or missed diagnoses.15PubMed Central. Sex Differences in Peripheral Artery Disease There may also be genuine biological differences in how female and male blood vessels respond to the stresses that cause atherosclerosis, though untangling those from diagnostic bias remains difficult.16PubMed Central. Gender Differences in Peripheral Vascular Disease
Genetics play a role too, but the picture is muddier than for heart disease. Several well-known PAD risk factors, including high cholesterol, diabetes, and hypertension, are themselves heritable. On top of that, there appear to be genetic variants that increase PAD susceptibility independently of those traditional risks. However, compared with coronary heart disease, relatively few PAD-specific genetic variants have been identified so far.17PubMed Central. The genetic basis of peripheral arterial disease: current knowledge, challenges, and future directions Family history of PAD or cardiovascular disease in general should still raise your alertness, even if researchers cannot yet hand you a neat list of genes to test.
Physical Inactivity and Sedentary Behavior
A lifetime spent sitting carries a measurable cost. People with a history of sedentary lifestyles have about a 46% higher odds of developing PAD compared with those who have been physically active.18PubMed Central. Low Lifetime Recreational Activity is a Risk Factor for Peripheral Arterial Disease A prospective study using wearable activity trackers found that over about eight years, participants in the highest third of daily sedentary time had a 43% greater risk of developing symptomatic PAD than those in the lowest third, while moderate-to-vigorous physical activity was protective.19Archives of Physical Medicine and Rehabilitation. Wearable device-measured sedentary behaviour, physical activity, and incident symptomatic peripheral artery disease: a prospective cohort study of 87,490 adults
The relationship between inactivity and PAD appears to be bidirectional. Prolonged sitting promotes the low-grade inflammation that feeds atherosclerosis. At the same time, PAD symptoms like leg pain during walking can discourage movement, trapping people in a cycle of worsening inactivity and worsening disease. A systematic review noted that sedentary behavior among PAD patients was associated with lower survival rates, independent of how much exercise those patients managed to get.20PubMed Central. The effects of sedentary behaviour on patients with peripheral arterial Disease: A systematic review Breaking up prolonged sitting, even without doing formal exercise, may help slow the downward spiral.
Environmental Exposures
Risk factors for PAD extend beyond your personal health habits. Long-term exposure to particulate air pollution, specifically PM10 (coarse particulate matter), has been linked to higher PAD prevalence. Interestingly, the same research found no clear connection between PAD and other common pollutants like nitrogen dioxide, sulfur dioxide, or ground-level ozone, suggesting it is the particulate fraction of dirty air that matters most for leg arteries.21PubMed Central. Environmental Pollution and Peripheral Artery Disease
Toxic metals are another environmental concern. Lead, cadmium, and arsenic have all been associated with atherosclerosis and increased cardiovascular risk, including PAD.22PubMed Central. Contaminant Metals as Cardiovascular Risk Factors: A Scientific Statement From the American Heart Association Cadmium exposure has been studied in particular detail. In the ARIC cohort, people with higher long-term cadmium exposure, measured through urine levels, had nearly double the risk of developing PAD even after adjusting for smoking and other cardiovascular risk factors.23Circulation: Cardiovascular Quality and Outcomes. Cadmium Exposure and Incident Peripheral Arterial Disease Cadmium is found in cigarette smoke, but the association held independently of smoking status, which means diet, occupational exposure, and environmental contamination also contribute. People living in industrial areas or working with batteries, pigments, or metal smelting face higher exposure.
Homocysteine
Homocysteine is an amino acid produced naturally during protein metabolism. When blood levels run high, it can damage the endothelial lining of arteries and promote clotting. In a large study of adults with hypertension, those with the highest homocysteine levels had a 53% greater risk of PAD compared with those whose levels were lowest, after accounting for standard cardiovascular risk factors.24PubMed Central. Association of plasma homocysteine with peripheral arterial disease in the hypertensive adults: A cross‐sectional study Homocysteine levels are influenced by diet, particularly folate and B-vitamin intake, and by kidney function. It is not yet routinely measured in PAD screening, but elevated homocysteine is one of the better-studied “non-traditional” risk factors and is worth being aware of, especially if you already have hypertension.
Chronic Kidney Disease
Kidney disease accelerates PAD through a specific mechanism involving mineral metabolism. When the kidneys fail to properly regulate calcium and phosphorus, the resulting imbalances promote calcification inside artery walls.25PubMed Central. Peripheral arterial calcification: prevalence, mechanism, detection, and clinical implications This type of calcification differs from ordinary plaque: it stiffens the vessel wall along its entire circumference rather than just building a bump of plaque on one side. The result is arteries that are rigid and noncompliant, which worsens blood flow restriction and makes the disease harder to treat with standard approaches like balloon angioplasty. As noted earlier, combining kidney disease with diabetes ramps up calcification and inflammation in PAD plaques far more than either condition alone.
Why So Many People Have PAD Without Knowing It
One of the most dangerous features of PAD is that it often produces no symptoms at all in its early and moderate stages. The classic symptom people associate with PAD, intermittent claudication, is pain or cramping in the calves or thighs during walking that goes away with rest. But population screening studies consistently show that most people with reduced ankle blood pressure, the hallmark measurement of PAD, do not report classic claudication. One study found that while about 4.5% of the population screened had abnormally low ankle-brachial index scores, only a small fraction, around 0.6%, had both low scores and classic claudication symptoms.26PubMed. Prevalence of symptomatic and asymptomatic peripheral arterial disease and the value of the ankle-brachial index to stratify cardiovascular risk
Even among people confirmed to have PAD by ankle-brachial index testing, a meaningful proportion never experience leg pain during exertion, even when they are formally tested during a timed walking protocol.27PubMed Central. Asymptomatic peripheral arterial disease is associated with more adverse lower extremity characteristics than intermittent claudication Being “asymptomatic” does not mean harmless: people with silent PAD still face elevated risks of heart attack, stroke, and poor leg function over time. The lack of obvious symptoms is one reason PAD is underdiagnosed and undertreated, especially in women, who present with atypical symptoms more frequently.
Socioeconomic and Racial Disparities
Where you live and what resources you have access to also shape your PAD risk. In the ARIC study, people with low household income had roughly two and a half times the risk of being hospitalized with PAD compared with higher-income individuals. Low education and living in a deprived neighborhood carried similarly elevated risks. These associations were partly explained by the fact that cardiovascular risk factors like smoking, diabetes, and hypertension are more prevalent in disadvantaged populations, and access to preventive care is worse, but even after accounting for those factors, the link between poverty and PAD persisted.28PubMed Central. Socioeconomic Status and Incidence of Hospitalization With Lower-Extremity Peripheral Artery Disease: Atherosclerosis Risk in Communities Study
Racial disparities compound the picture. Black patients with PAD are more likely to undergo amputation and less likely to receive revascularization or wound care before amputation than white patients.29PubMed Central. Socioeconomic Inequality and Peripheral Artery Disease Prevalence in US Adults Current evidence suggests that biological differences between racial groups are less likely to explain these outcome disparities than social determinants of health, including neighborhood poverty, healthcare access, insurance status, and differential referral patterns.30PubMed Central. Racial and Socioeconomic Health Disparities in Peripheral Artery Disease In other words, the disparity is largely a healthcare system failure, not a biological inevitability.
When Leg Pain Is Not PAD
Not every case of leg pain during walking is PAD, and the overlap with other conditions can cause confusion. Lumbar spinal stenosis, a narrowing of the spinal canal in the lower back, can produce leg symptoms during walking that closely mimic intermittent claudication. Both conditions cause pain with activity and relief with rest, though spinal stenosis pain often improves with bending forward and worsens with standing upright, while PAD claudication typically has no positional preference. The ankle-brachial index is recommended as a screening tool when claudication symptoms are atypical, precisely because it can help separate vascular causes from spinal causes.31PubMed Central. The validity of ankle-brachial index for the differential diagnosis of peripheral arterial disease and lumbar spinal stenosis in patients with atypical claudication Venous insufficiency, neuropathy, and musculoskeletal problems can also produce leg discomfort that gets lumped under the PAD umbrella before proper testing is done. If you have leg symptoms that concern you, the ankle-brachial index test is painless, takes a few minutes, and is one of the most reliable ways to sort out whether reduced arterial blood flow is actually the problem.
Exercise After Diagnosis
Walking programs are widely recommended for people with PAD, and supervised exercise has been shown in clinical trials to improve walking distance and quality of life. The mechanism behind that improvement, though, is not entirely what you might expect. Small studies have not found significant effects of exercise on increasing capillary density in leg muscles of PAD patients, and there is no good evidence that exercise improves microcirculatory oxygen delivery in affected legs.32PubMed. Walking Exercise Therapy Effects on Lower Extremity Skeletal Muscle in Peripheral Artery Disease The benefits may instead come from improved muscle metabolic efficiency, better walking biomechanics, reduced inflammation, and increased pain tolerance rather than from any reversal of the arterial blockage itself. That does not diminish the value of walking programs, but it does mean you should not expect exercise alone to open up narrowed arteries. The blockages remain; your body just learns to work around them more effectively.