The progression of Alzheimer's disease and other dementias

4. Vascular dementia

Vascular dementia develops when brain cells are deprived of oxygen and die. This happens either because of diseases of the very small blood vessels deep in the brain (known as subcortical vascular dementia), or after a major stroke or a series of smaller strokes (both known as stroke-related dementia).

It is sometimes difficult to tell whether a person has Alzheimer’s disease or vascular dementia. It is also not unusual to have a mixed form of dementia, meaning the person has both vascular dementia and Alzheimer’s disease together.

Subcortical and stroke-related vascular dementia share some symptoms but have others that differ. They also tend to progress in different ways. Subcortical vascular dementia usually develops gradually and progresses slowly, like Alzheimer’s disease. In contrast, when vascular dementia follows a large stroke, symptoms usually develop suddenly. Stroke-related dementia often then follows a ‘stepped’ progression, with long periods when symptoms remain the same and short periods when they suddenly worsen (this pattern is seen because each stroke further damages the brain).

The symptoms of vascular dementia are overall broadly similar to those of Alzheimer’s disease – and become more similar as the dementia progresses – but with some important differences. The main early symptoms of vascular dementia are often not forgetfulness but rather:

  • difficulties with planning or organising, following steps (eg cooking a meal) or making decisions
  • slower speed of thought
  • problems concentrating, including short periods of confusion.

You can help someone with vascular dementia by breaking tasks down into smaller steps and giving them plenty of time to think and speak.

A person with early stage vascular dementia is prone to apathy, mood swings and being unusually emotional. They are also particularly likely to have anxiety and depression, partly because they are more aware of the problems their dementia is causing.

Vascular dementia after a major stroke is often accompanied by physical symptoms, such as weakness of a limb, or problems with vision or speech. These early symptoms arise when the stroke has damaged a particular part of the brain. With rehabilitation the symptoms might get a little better or stabilise for a time.

As vascular dementia progresses, the symptoms become closer to those of middle and eventually later stage Alzheimer’s disease. Problems with memory loss, confusion, disorientation, reasoning and communication all become worse. The behavioural changes seen as vascular dementia progresses, such as irritability and agitation, are also similar to those of Alzheimer’s disease. Delusions, and less often hallucinations, are also seen. The late stage of vascular dementia is largely as described above for Alzheimer’s disease.

Each person will experience dementia differently. On average, people with vascular dementia live for around five years after symptoms begin, less than the average for Alzheimer’s disease. In many cases, the person’s death will be caused by a stroke or heart attack. For more information see our page on vascular dementia.