Atypical Alzheimers disease | Alzheimer's Society

Publish date: 2024-05-04

Problems with memory are the most common symptom of Alzheimer’s disease, but around 1 in 20 people with Alzheimer’s have different early symptoms. This is called atypical Alzheimer’s disease. It is caused by the same kinds of changes in the brain as typical Alzheimer’s, but these changes start in a different part of the brain and so cause different symptoms.

The two most common types of atypical Alzheimer’s are frontal variant Alzheimer’s disease (fvAD) and posterior cortical atrophy (PCA).

Frontal variant Alzheimer’s disease (fvAD)

For about 1 in 50 people who have Alzheimer’s disease, the condition affects the frontal lobes of their brain during the earlier stages – something that wouldn’t happen until much later in most typical cases. When this happens, the condition is known as ‘frontal variant Alzheimer’s disease’ (fvAD). For more information on the different lobes of the brain and their functions, see The brain and dementia.

The damage to the frontal lobes can cause:

However, most people who have fvAD will show some of both types of symptoms.

A person who has fvAD is likely to show changes in their personality and behaviour. They may:

A person who has fvAD is also likely to have symptoms related to ‘executive function’ and may:

Some people who have the condition may also have memory problems, but these are generally much less severe during the earlier stages than in typical Alzheimer’s disease.

Sometimes fvAD is misdiagnosed as a more common type of dementia that affects the frontal lobes of a person’s brain. This can include vascular dementia or behavioural variant frontotemporal dementia.

As with other types of Alzheimer’s disease, there is no treatment that can slow the progression of fvAD. Drugs such as donepezil, rivastigmine and galantamine may improve a person’s symptoms. In people with other types of dementia, such as typical Alzheimer’s disease, they can help a person to think more clearly. However, there haven’t been any clinical trials to test how well these drugs work for people who have fvAD. This is because it is a rare type of dementia and is very difficult to diagnose correctly.

People who have frontal variant Alzheimer’s disease are often given similar treatment to people with behavioural variant frontotemporal dementia. For more information see Frontotemporal dementia: what is it?

Posterior cortical atrophy (PCA)

Posterior cortical atrophy (PCA) is most often caused by the same changes in a person’s brain that cause Alzheimer’s disease. However, in PCA the disease starts in a different part of the brain. At first it mainly affects the back of the brain – a region called the ‘visual cortex’. This part of the brain processes information that comes from a person’s eyes and turns it into what the person sees. PCA can also be caused by other types of disease that affect a person’s visual cortex, but this is less common.

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