Arteriosclerosis is a broad term for any hardening or stiffening of the arteries. Atherosclerosis is one specific type of arteriosclerosis, caused by plaque buildup inside artery walls. In other words, all atherosclerosis is arteriosclerosis, but not all arteriosclerosis is atherosclerosis. The two terms are often used interchangeably, even by doctors, but they describe different levels of the same problem.
How the Two Terms Relate
Think of arteriosclerosis as the umbrella category. It literally means “hardening of the arteries” and covers any condition where arteries thicken, stiffen, or lose their natural flexibility. Several different processes can cause this, and atherosclerosis is the most common one.
Atherosclerosis specifically involves plaque, a sticky buildup of cholesterol, fat, calcium, blood cells, and other substances that collects inside artery walls. Over time, this plaque hardens and narrows the artery, restricting blood flow. It targets large and medium-sized arteries like those supplying the heart, brain, and legs.
There are other forms of arteriosclerosis that have nothing to do with plaque, which is where the distinction matters.
The Three Types of Arteriosclerosis
Arteriosclerosis comes in three main forms, each affecting different sized blood vessels through different mechanisms.
Atherosclerosis is by far the most common and most dangerous. It develops in large and medium arteries when cholesterol-rich plaque accumulates in the vessel wall. This is the type responsible for heart attacks, strokes, and peripheral artery disease. When most people say “hardening of the arteries,” this is what they mean.
Arteriolosclerosis affects the smallest blood vessels, called arterioles. It comes in two forms. The more common one, hyaline arteriolosclerosis, is linked to chronic high blood pressure and causes a glassy thickening of tiny artery walls. In the kidneys, this can gradually damage the filtering units and lead to chronic kidney failure. In the brain, it can weaken small vessel walls enough to cause microaneurysms that may rupture and bleed. The second form, hyperplastic arteriolosclerosis, involves layers of smooth muscle cells building up concentrically, like rings in a tree trunk, and is associated with severe hypertension.
Mönckeberg sclerosis is a distinct condition where calcium deposits form in the middle muscular layer of small and medium arteries. It’s most commonly seen in older adults and in people with diabetes or chronic kidney disease. Unlike atherosclerosis, Mönckeberg sclerosis doesn’t narrow the inside of the artery, so it typically doesn’t block blood flow. In advanced cases, though, the affected vessels become rigid and lose their ability to expand and contract. It’s often discovered incidentally when calcified arteries show up on routine X-rays.
How Atherosclerosis Develops
Atherosclerosis unfolds in stages over years or decades. It starts when the inner lining of an artery becomes damaged or dysfunctional. Areas where blood flow is turbulent, like branches and curves in the arterial tree, are especially vulnerable.
Once the lining is compromised, LDL cholesterol particles slip through it and accumulate in the artery wall. The body’s immune system treats this like an injury: white blood cells move in and try to clean up the cholesterol, but they become overloaded and transform into bloated “foam cells.” This early stage, called a fatty streak, is the first visible sign of atherosclerosis and can appear as early as childhood.
Over time, more cholesterol, immune cells, and cellular debris pile up. A fibrous cap forms over the top of the deposit, creating a more structured plaque. The plaque progressively thickens the artery wall, and calcium deposits can make it hard and rigid. Lesions that begin in the inner lining eventually affect all three layers of the arterial wall.
The most dangerous moment isn’t necessarily when the artery gets extremely narrow. Plaques that are only moderately sized but have a large, soft, cholesterol-rich core under a thin cap are the ones most likely to rupture. When a plaque ruptures, it exposes its contents to the bloodstream, triggering a blood clot that can suddenly block the artery. This is the mechanism behind roughly 75% of fatal heart attacks. In the coronary arteries, the blockages that cause heart attacks frequently occur at spots that were less than 50% to 70% narrowed before the event.
Why Atherosclerosis Matters Most
Atherosclerosis is the underlying cause of nearly all coronary artery disease, most strokes, and peripheral artery disease. Cardiovascular diseases collectively kill an estimated 19.8 million people per year worldwide, accounting for about 32% of all deaths globally. Of those deaths, 85% are due to heart attacks and strokes, both of which are overwhelmingly driven by atherosclerosis.
The location of plaque buildup determines which problems develop. Atherosclerosis in the coronary arteries restricts blood flow to the heart muscle and can cause chest pain or heart attacks. In the carotid arteries supplying the brain, it causes strokes. In the arteries of the legs, it leads to peripheral artery disease, with symptoms like leg pain during walking and slow-healing wounds. Unlike coronary plaques, which often rupture when only moderately narrowed, dangerous carotid plaques tend to be severely narrowed and visibly ulcerated.
Risk Factors They Share
High blood pressure is a driver of both atherosclerosis and arteriolosclerosis. Beyond that, the major risk factors for atherosclerosis specifically include high LDL cholesterol, obesity, type 2 diabetes, high blood sugar, smoking, physical inactivity, poor diet, and chronic psychological stress.
Lifestyle changes carry real weight. Regular physical activity and structured exercise can reduce atherosclerotic cardiovascular disease risk by up to 50%. Heart-healthy dietary patterns, maintaining a healthy body weight, getting adequate sleep, and managing stress are all independently associated with lower risk. These factors work together: obesity and high blood sugar promote the metabolic conditions that accelerate plaque formation, while exercise and diet directly counteract them.
How These Conditions Are Detected
Since atherosclerosis can develop silently for decades before causing symptoms, several imaging and functional tests can detect it early.
- Coronary calcium scan: A CT scan of the heart that detects calcium deposits in the coronary arteries. Higher calcium scores indicate more plaque buildup and greater heart attack risk, sometimes years before symptoms appear.
- Doppler ultrasound: Measures blood flow speed at various points in the body and can reveal narrowed arteries based on changes in flow patterns.
- Ankle-brachial index: Compares blood pressure at the ankle to blood pressure in the arm. A significant difference suggests atherosclerosis has narrowed the leg arteries.
- Angiography: MRA or other imaging can directly visualize narrowing, hardening, or aneurysms in large arteries.
Arteriolosclerosis, because it affects tiny vessels deep in organs like the kidneys and brain, is harder to detect with standard imaging and is often identified through its consequences: declining kidney function, or small-vessel changes seen on brain MRI.
Mönckeberg sclerosis is sometimes the easiest to spot. Heavily calcified arteries can appear as bright, pipe-like structures on plain X-rays, though this finding alone doesn’t mean blood flow is compromised.