There is no single test for vascular dementia. The GP will first need to rule out conditions that can have similar symptoms, particularly depression. Symptoms could also be caused by infections, vitamin and thyroid deficiencies (diagnosed from a blood test) and side effects of medication.
The doctor will also talk to the person about their medical history (eg high blood pressure or diabetes). This will include questions about dementia or cardiovascular disease in close family members. The doctor will probably do a physical examination and will ask about how the person's symptoms are currently affecting their life. The GP or a practice nurse may ask the person to do some tests of mental abilities. It is often helpful if a close friend or family member accompanies the person to medical appointments. They may be able to describe subtle changes that the person themselves has not noticed, such as starting to struggle with daily activities.
The GP may feel able to make a diagnosis of vascular dementia at this stage. If not, they will generally refer the person to a specialist. This might be an old-age psychiatrist (who specialises in the mental health of older people) based in a memory service, or a geriatrician (who specialises in the physical health of older people) in a hospital.
The specialist will assess the person's symptoms in more detail. The way that symptoms developed - in steps or more gradually - may suggest different underlying diseases. The person's thinking and other mental abilities will also be assessed further with a wider range of tests. In someone with vascular dementia, the test might show slowness of thought and difficulties thinking things through, which are often more common than memory loss.
A person suspected of having vascular dementia will generally have a brain scan to look for any changes that have taken place in the brain. A scan such as CT (computerised tomography) or MRI (magnetic resonance imaging) may rule out a tumour or build-up of fluid inside the brain. These can have symptoms similar to those of vascular dementia. A CT scan may also show a stroke or an MRI scan may show changes such as infarcts or damage to the white matter. If this is the case, the brain scan will be very helpful in diagnosing the dementia type, rather than simply ruling out other causes.
If the person has dementia, and the circumstances mean it is best explained by vascular disease in the brain, a diagnosis of vascular dementia will be made. For example, the dementia may have developed within a few months of a stroke, or a brain scan may show a pattern of disease that explains the dementia symptoms.
The diagnosis should be communicated clearly to the person and usually also those closest to them, along with a discussion about the next steps.