Types and Causes of Vascular Dementia

Vascular dementia is not a single disease, but an “umbrella term” for several different ways that blood vessel damage can affect the brain. The specific subtype you have depends on whether the damage happened in large arteries or small capillaries, and whether it occurred suddenly or built up slowly over many years ^[1][2]. It is important to note that these subtypes are not mutually exclusive and often overlap in clinical practice.

Subcortical Ischemic Vascular Dementia (SIVD)

This is a very common descriptive pattern of vascular dementia. It is driven by small-vessel disease, which affects the tiny arteries deep inside the brain ^[1]. Rather than one large stroke, SIVD involves a chronic lack of blood flow and nutrients to the brain’s “white matter”—the wiring that connects different brain regions ^[3].

Because the damage is deep and widespread, SIVD often causes a gradual decline that can look similar to Alzheimer’s disease ^[4]. Common signs include mental slowness, difficulty focusing, and physical changes like walking with shorter, more hesitant steps ^[5][6].

Multi-Infarct Dementia (MID)

Multi-infarct dementia is caused by a series of small strokes, often called infarcts, that occur over time ^[3]. Each stroke might be so small that you don’t even notice it when it happens—these are sometimes called “silent strokes” ^[7].

The hallmark of MID is a stepwise decline ^[3]. This means your thinking and physical abilities might stay the same for months, then suddenly “drop” to a new, lower level after a small stroke, before leveling off again ^[8]. The specific symptoms you experience depend on where these strokes occurred; for example, a stroke in a speech center will cause sudden trouble with language ^[8].

Post-Stroke Dementia

This term is used when cognitive impairment follows a major, visible stroke ^[7]. While not everyone who has a stroke will develop dementia, a significant portion of stroke survivors experience noticeable cognitive changes within months of the event ^[9].

The initial decline is usually immediate. However, if thinking continues to worsen long after the stroke has healed, it may be a sign of new vascular injury, sleep problems, medication effects, depression, or co-existing Alzheimer’s ^[10]. Any sudden worsening should be evaluated promptly.

CADASIL: A Genetic Subtype

CADASIL stands for Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy. It is a rare, inherited form of small-vessel disease associated with variants in the NOTCH3 gene ^[11].

It is often suspected if a person has:

• A family history of strokes or dementia at a young age (often starting in the 40s or 50s) ^[11].
• A history of severe migraines with “aura” (visual disturbances) ^[12].
• Recurrent small strokes and mood disorders, like severe depression ^[11].

If CADASIL is suspected, specialist genetic counseling is recommended. While genetic factors play a primary role, modifying traditional vascular risk factors is still important for overall vascular health ^[12].

The Role of Mixed Dementia

While these categories help doctors understand your condition, the reality is that many people have more than one type of damage. Research shows that a large proportion of older adults with vascular changes also show signs of Alzheimer’s disease pathology ^[13]. This is known as mixed dementia ^[14].

In mixed dementia, vascular issues and Alzheimer’s pathology can both contribute to cognitive decline ^[15]. Because of this, managing your vascular health—like optimizing your blood pressure—is an important part of your overall care plan, as preventing new vascular events helps protect your remaining cognitive function ^[16].