Atypical Alzheimer’s disease

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 starts in a different part of the brain and so causes different symptoms.

The two most common types of atypical Alzheimer’s are:

• Frontal variant Alzheimer’s disease (fvAD)
  See information below.
   
• Posterior cortical atrophy (PCA)
  See information on the following page.

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). 

The damage to the frontal lobes can cause:

• behavioural symptoms (behavioural Alzheimer’s disease) or
• problems with a type of thinking known as ‘executive function’ (dysexecutive Alzheimer’s disease).

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

For more information on the different lobes of the brain and their functions, see Dementia and the brain.

What are the symptoms of fvAD?

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

• Lose their inhibitions – behave in socially inappropriate ways or without thinking. This could include making insensitive or inappropriate comments or invading someone’s personal space, acting in a sexually inappropriate way, staring at strangers, or being verbally or physically aggressive.
• Lose motivation to do things that they used to enjoy.
• Lose the ability to understand what others might be thinking or feeling, become less sympathetic to the needs of others and show less social interest or personal warmth. They may also show reduced humour and their reactions might be inappropriate, for example laughing at another person’s misfortune.
• Show repetitive, compulsive or ritualised behaviours – this can include repeated use of phrases or gestures, hoarding and obsessions with timekeeping. It may also include new interests, such as music or spirituality.
• Changes in eating habits, such as craving sweet, fatty foods or carbohydrates and forgetting their table manners. They may also no longer know when to stop eating and drinking.
   

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

• Struggle with tasks which follow a series of steps – for example making a cup of tea.
• Find it hard to think about more than one piece of information at a time when making a decision.
• Be easily distracted and find it hard to concentrate.
• Sometimes fixate on a specific thought or on something in the room.
• Copy other people’s behaviour.

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.

Getting a fvAD diagnosis and treatment

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.