On the tip of your tongue…

Dr Laura PhippsKirsty MaraisClaire LucasRobin BrisbourneKaty StubbsEd PinchesGlyn Morris

When we hear the word dementia, changes in memory are the primary symptom many of us think of, however there is a range of other symptoms many people face to varying degrees. Just last week, Terry Jones – best known as a member of Monty Python – highlighted this with the announcement that he is living with primary progressive aphasia (PPA), a form of frontotemporal dementia. This week (26 Sep to 2 Oct) is the second World Frontotemporal Dementia Awareness Week, so we wanted to draw attention to the lesser known effects of this devastating condition.

What is primary progressive aphasia?

The term PPA covers three separate conditions, all of which affect speech and language in different ways. These are

  • semantic dementia
  • progressive non-fluent aphasia
  • logopenic primary aphasia.

People with PPA can show other symptoms too, but PPA is diagnosed if problems with language appear before other symptoms.

In semantic dementia, people gradually lose their knowledge of the meaning of words while still being able to speak relatively fluently. At the early stages, they can still speak in sentences but may replace a number of words with increasingly vague terms. For example, ‘rose’ may become ‘flower’ and ‘Labrador’ becomes ‘dog’ then ‘animal’, before ultimately they may both be referred to as a ‘thing’. People with semantic dementia can also struggle to know what everyday objects are for, and may not understand when the meaning of a word is explained to them.

People with progressive non-fluent aphasia (PNFA) find speech involves an increasing amount of effort. Despite knowing what they want to say, someone with PNFA finds it difficult to actually produce the words, making their speech slow and laboured. They may also make grammatical errors and miss out words, making it difficult to understand what they are trying to say. Some people with PNFA can develop word reversals and say the opposite to what they intended, such as saying yes when they mean no.

The third type of PPA is logopenic primary aphasia, and people with this form are generally able to understand language and produce speech, but may struggle to find the words they want to use. This leads to slow speech with frequent pauses as people search for the word they want to use. People with logopenic primary aphasia can also struggle to say words correctly, and find understanding sentences difficult, making communication increasingly problematic.
As each of these conditions progresses, people with primary progressive aphasia find it more difficult to communicate with others, both in producing speech and understanding what other people are saying. There can also be other symptoms, such as in PNFA, where people may experience problems with movement, such as tremors and unsteadiness. The progression of semantic dementia can result in the development of behavioural changes, such as obsessions and narrowed interests, compulsive and complex repetitive behaviours, and increased sensitivity to pain and other stimuli. These behavioural changes are also seen in the other main form of frontotemporal dementia, called behavioural variant frontotemporal dementia, often making it difficult to differentiate people with semantic dementia at the later stages of the disease.

What is happening in the brain?

Primary progressive aphasia is a type of frontotemporal dementia, which affects either the frontal or temporal lobes of the brain, or both. Researchers have shown that brain cells die in these regions due to the build-up of toxic proteins, which include tau, FUS and TDP-43. A small number of people have faulty genes that lead to the build-up of these proteins, but in the majority of people there is no clear genetic cause of PPA.

FTD brain scans

Progression of damage through the temporal lobe in semantic dementia. Image credit – Dr Jon Rohrer (UCL)

The understanding and production of language is handled by the temporal lobes, and it is these areas that are predominantly affected in PPA. The language centres of the brain are located on the left side of the brain in the majority of people (95% of right handed people and 60% of left handed people), and it is this area that is largely affected in semantic dementia and progressive non-fluent aphasia. In logopenic primary aphasia, the loss of brain cells is seen in areas more towards the back of the brain.

While PPA is considered to be a type of frontotemporal dementia, the changes in brain cells seen in logopenic primary aphasia can more closely resemble what happens in Alzheimer’s disease in some people. However, if problems with speech and language appear before memory problems, then a doctor is more likely to diagnose LPA.

What research is going on?

As the UK’s leading charity funding dementia research, Alzheimer’s Research UK has driven £12.9m into studies of both the causes of frontotemporal dementia and potential ways to treat the disease.

In ongoing studies, researchers are trying to understand how toxic proteins cause damage in the brain, whether waste disposal systems can be boosted to remove toxic proteins, and trying to create drugs that could treat the disease. They are also trying to better understand the biological fingerprint of the disease, as this may assist with improving the accuracy of diagnosis.

Donate today to support our pioneering research.

Where can I turn to for support?

We’re also providing financial backing to the Rare Dementia Support Groups, a specialist service that provides opportunities for people affected by rare dementias to engage in research and access support. They have a dedicated PPA support group, and you can find out more about this at www.raredementiasupport.org.

You can find more information about frontotemporal dementia on our website or at FTDtalk.org, a website run by researchers working to tackle the disease.

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