CADASIL is a rare inherited disorder that occurs when thickened blood vessel walls reduce the flow of blood to the brain, leading to strokes, migraines, and progressive cognitive decline that can eventually result in dementia.

What is CADASIL?

CADASIL stands for cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. This long name describes what happens in the body during this condition. Cerebral refers to the brain, where the disease mainly affects the body. Autosomal dominant describes how the condition is inherited, meaning that only one copy of an abnormal gene from one parent can cause the disorder. Arteriopathy means there is a disease affecting the arteries, which are the blood vessels that carry blood throughout the body. Subcortical infarcts are small areas of dead tissue below the outer layer of the brain, caused by lack of blood supply. Leukoencephalopathy refers to damage affecting the white matter of the brain, which contains nerve fibers that help different parts of the brain communicate with each other.

CADASIL is considered the most common form of hereditary stroke disorder. The condition primarily affects small and medium-sized blood vessels in the white matter of the brain. When these blood vessels become damaged, they cannot deliver enough oxygen and nutrients to brain tissue, leading to the various symptoms that people with CADASIL experience.

This is a progressive condition, meaning symptoms typically worsen over time. While the disease is present from birth due to genetic mutations, most people do not show signs of illness until they reach adulthood. The rate at which the disease progresses can vary greatly from person to person, even within the same family.

Who Gets CADASIL?

CADASIL can affect anyone regardless of gender, race, or ethnicity. The disorder has been identified in families from all over the world, including European, American, Middle Eastern, African, and Asian populations. Both men and women are affected equally by this condition.

Because CADASIL is a rare disease and is often misdiagnosed or goes unrecognized, determining its exact frequency in the general population has been challenging. Studies have estimated different prevalence rates depending on the population studied. One investigation found a prevalence of approximately 2 cases per 100,000 adults for genetically confirmed CADASIL, though researchers believe the actual number of people carrying mutations may be higher, possibly around 4 cases per 100,000 adults.

More recent large-scale genetic studies have suggested that mutations associated with CADASIL might be more common than previously thought, with some estimates as high as 3 to 4 cases per 1,000 people. This higher number may include people with milder forms of the disease who never develop severe symptoms or receive a diagnosis. The frequencies of disease-causing mutations appear to be higher in certain Asian populations compared to European populations, though CADASIL has been documented across all continents.

What Causes CADASIL?

CADASIL is caused by mutations in a gene called NOTCH3, which is located on chromosome 19. This gene provides instructions for making a protein that sits on the surface of smooth muscle cells, which are the cells that surround and support blood vessels. The NOTCH3 protein plays an important role in the normal functioning of these muscle cells.

When mutations occur in the NOTCH3 gene, the protein it produces becomes abnormal. This faulty protein accumulates in the walls of small and medium-sized blood vessels throughout the body, particularly in the brain. Over time, this accumulation causes the blood vessel walls to thicken and become damaged. The smooth muscle cells that normally help vessels function properly gradually die off, and the vessels themselves become increasingly damaged.

As blood vessels deteriorate, they can no longer effectively deliver blood to brain tissue. This reduced blood flow means that parts of the brain receive too little oxygen and nutrients to survive, leading to tissue death in small areas throughout the brain. This process particularly affects the white matter, which is the tissue in the brain made up of nerve fibers covered by a protective coating.

In most cases, CADASIL is inherited from a parent who also has the condition or carries the mutation. Because it follows an autosomal dominant pattern of inheritance, only one parent needs to have the mutation for a child to inherit it. Each child of an affected parent has a 50 percent chance of inheriting the mutated gene. However, in rare instances, CADASIL can occur due to a spontaneous genetic mutation that happens for unknown reasons, meaning neither parent carries the mutation.

Risk Factors for CADASIL

The primary risk factor for developing CADASIL is having a family history of the condition. If one parent has CADASIL or carries the NOTCH3 mutation, each of their children has a one in two chance of inheriting the genetic change. This means that siblings, parents, and children of people with CADASIL should be aware of their potential risk.

While having the genetic mutation is necessary for developing CADASIL, research has shown that certain lifestyle factors and health conditions can influence when symptoms begin and how quickly the disease progresses. Studies have demonstrated that common stroke risk factors, particularly smoking and high blood pressure, are associated with earlier onset of strokes and a faster rate of brain damage visible on imaging scans in people with CADASIL.

Smoking appears to have a particularly significant negative impact on the progression of CADASIL. People with CADASIL who smoke tend to experience strokes at younger ages compared to non-smokers with the condition. Similarly, uncontrolled high blood pressure can accelerate damage to already vulnerable blood vessels in the brain.

Other cardiovascular risk factors such as high cholesterol, diabetes, obesity, and physical inactivity may also contribute to worse outcomes in CADASIL, although these have not been studied as extensively as smoking and blood pressure. These factors do not cause CADASIL itself, but they appear to worsen the underlying blood vessel damage and may trigger symptoms to appear earlier in life.

Symptoms and How They Affect Daily Life

The symptoms of CADASIL typically begin to appear between the ages of 20 and 40 years, though this timing varies considerably. Some people may not notice any symptoms until they are 50 or 60 years old, while rarely, symptoms can begin in childhood. The most common age for symptoms to first appear is during the mid-30s to mid-40s.

Migraine headaches, often accompanied by an aura (sensory disturbances that occur before or during the headache, such as seeing flashing lights or experiencing tingling sensations), are frequently the first symptom people notice. These migraines can be severe and disabling. The aura may include visual disturbances like bright or colored lights, sensory changes such as tingling, speech difficulties like trouble finding words, or even temporary weakness or confusion. Not everyone with CADASIL experiences migraines, but they occur in a significant portion of affected individuals.

Strokes and transient ischemic attacks, sometimes called mini-strokes or TIAs, are the most frequent and serious manifestation of CADASIL, affecting approximately 85 percent of people who develop symptoms. These typically occur without the traditional risk factors usually seen in common strokes. The strokes in CADASIL are usually lacunar strokes, which are small strokes that occur deep within the brain rather than on its surface. The average age when these ischemic episodes begin is around 46 years, though they can occur anywhere from age 30 to 70.

Common symptoms from these strokes include sudden weakness or numbness on one side of the body, difficulty with balance and coordination, or problems with movement. These strokes often occur without warning and can happen repeatedly over time. Even when strokes are “silent,” meaning they don’t cause obvious symptoms at the time, they still cause cumulative damage to the brain.

Progressive decline in memory and thinking skills is another major feature of CADASIL. This cognitive impairment typically worsens gradually over years and decades. People may have difficulty with attention, problem-solving, planning complex tasks, or processing information quickly. Memory problems, particularly short-term memory, become increasingly noticeable. This progressive cognitive decline often leads to vascular dementia, a type of dementia caused by reduced blood flow to the brain. By age 65, most individuals with CADASIL will have significant cognitive impairment or dementia.

Mental health changes are also common in CADASIL and can significantly impact quality of life. Depression occurs frequently and may appear before other symptoms become obvious. People may also experience apathy, meaning they lose interest in activities they once enjoyed and lack motivation. Anxiety, irritability, and in rare cases, bipolar disorder have also been reported. Some individuals may experience changes in personality or behavior over time.

Less common symptoms include seizures, vision problems such as visual field defects, slow movements and tremors resembling Parkinson’s disease, episodes of confusion or even coma caused by acute encephalopathy (sudden dysfunction of the brain), and rapid onset of vertigo with nausea, vomiting, and difficulty walking. Some people may develop difficulty controlling their bladder or experience problems with their gait even without having had an obvious stroke.

The combination and severity of symptoms varies greatly from person to person, even among family members who share the same genetic mutation. This variability makes it difficult to predict exactly how CADASIL will affect any individual. However, the general pattern is one of slow progression, with symptoms gradually worsening over many years.

Prevention and Risk Reduction

Because CADASIL is a genetic disorder, there is no way to prevent someone who carries the mutation from developing the condition. However, there are important steps that people with CADASIL can take to potentially slow disease progression and reduce the risk of strokes and other complications.

For individuals with CADASIL, controlling cardiovascular risk factors is extremely important. Managing high blood pressure is a top priority, as uncontrolled hypertension can worsen damage to already vulnerable blood vessels. People with CADASIL should have their blood pressure checked regularly and work with their doctor to keep it within a healthy range through lifestyle changes or medication if needed.

Smoking cessation is critically important for anyone with CADASIL who smokes. Research clearly shows that smoking is associated with earlier onset of stroke and increased rate of brain damage in CADASIL. Quitting smoking at any age can help protect the brain from further damage.

Maintaining healthy cholesterol and blood glucose levels is also recommended. While these factors have not been studied as extensively in CADASIL as in common stroke, they contribute to overall vascular health. This includes following a heart-healthy diet, maintaining a healthy weight, and taking medications if prescribed by a doctor.

Regular physical exercise is encouraged as part of an active lifestyle. Exercise supports overall cardiovascular health and may help maintain cognitive function. However, people with CADASIL should discuss appropriate exercise levels with their healthcare provider, especially if they have experienced strokes or have other limitations.

For family planning purposes, people with CADASIL or those who have a family history of the condition may wish to consult with a genetic counselor. Genetic testing can determine whether someone carries the NOTCH3 mutation before symptoms appear. This information can help individuals make informed decisions about having children and understanding their children’s risk. Prenatal testing and preimplantation genetic diagnosis are options for couples concerned about passing CADASIL to their children, though these are personal decisions that should be discussed with genetic counselors and healthcare providers.

Mental health care is an important but often overlooked aspect of prevention. Because depression and other mood disorders are common in CADASIL, seeking treatment for these conditions is important for overall quality of life. This might include counseling, cognitive behavioral therapy, or medication for depression and anxiety.

How the Disease Changes the Body

Understanding what happens inside the body during CADASIL helps explain why symptoms occur and why they progress over time. The disease begins at the molecular level with abnormal NOTCH3 protein, but its effects eventually become visible in the structure and function of the brain.

The fundamental problem in CADASIL is the progressive damage to small and medium-sized arteries, particularly in the brain. The abnormal NOTCH3 protein accumulates in the walls of these blood vessels, forming granular deposits that can be seen under special microscopy. This accumulation affects the smooth muscle cells that normally help blood vessels maintain their shape and regulate blood flow.

As the disease progresses, these smooth muscle cells undergo changes and eventually die. The blood vessel walls become thickened and stiff, a process called hypertrophy. The vessels lose their ability to expand and contract normally in response to the brain’s changing needs for blood flow. The thickened walls also narrow the space inside the vessels through which blood can flow, reducing the amount of blood that reaches brain tissue.

This compromised blood supply leads to chronic underperfusion of the brain, meaning brain tissue consistently receives less blood than it needs to function optimally. Research has shown that in people with CADASIL, cerebral blood flow, blood volume, glucose utilization, and the vessels’ ability to respond to changes in demand are all impaired. The brain essentially operates in a state of chronic mild oxygen and nutrient deprivation.

When blood flow becomes critically reduced in a particular area, brain tissue in that region dies, creating what is called an infarct. In CADASIL, these infarcts typically occur in the subcortical regions, which are the areas deep within the brain beneath the outer cortex. These small infarcts accumulate over time, even when they don’t cause noticeable symptoms at the moment they occur.

The white matter of the brain is particularly vulnerable in CADASIL. White matter consists of nerve fibers covered by myelin, a fatty protective coating that helps signals travel quickly between different parts of the brain. Reduced blood flow damages both the nerve fibers and the myelin, leading to leukoencephalopathy. This damage disrupts the connections between different brain regions, interfering with cognitive functions, movement, and other neurological processes.

Over time, the accumulated damage leads to brain atrophy, meaning the brain tissue actually shrinks. This can be seen on imaging scans as enlarged fluid-filled spaces within the brain. The progressive loss of brain tissue and connections explains why cognitive decline worsens gradually and why people eventually develop dementia.

The damaged blood vessels also become fragile and prone to small bleeds, called cerebral microbleeds. These tiny hemorrhages can be detected on certain types of brain imaging scans. While each individual microbleed is small, their accumulation over time contributes to brain damage.

Interestingly, while CADASIL primarily causes symptoms related to the brain, the blood vessel changes occur throughout the body. The same abnormal protein deposits can be found in blood vessels in the skin and other organs. This is why doctors can sometimes diagnose CADASIL by examining a small sample of skin under a microscope, looking for the characteristic protein deposits in skin blood vessels.