Primary progressive aphasia (PPA) refers to a group of dementias that affect a person’s speech and language, in other words, a person who develops PPA losses their ability to speak, read, write, and understand what others are saying. To break down the term primary progressive aphasia: ‘primary’ relates to it being brain tissue changes rather than an external cause, ‘progressive’ means worse over time and ‘aphasia’ refers to a neurological (brain-related) language problem.
The three most common types or variants of PPA are:
Progressive nonfluent aphasia (PNFA), also known as nonfluent/agrammatic variant of PPA (nfvPPA), affects a person’s ability to use speech (known as aphasia), form sentences that make sense, or use grammar appropriately (known as agrammatism). For instance, somebody with nfvPPA might have problems producing the words that they want to say – their speech might sound very slow or physically difficult, or they may get the order of words in a sentence mixed up. While their understanding or memory of the meaning of words is intact, their ability to produce and comprehend speech, particularly long or complex sentences is affected. Difficulties with word order and sentences can be present in writing as well. Some people develop problems with swallowing, also caused by degeneration of the parts of the brain that control actions of certain muscles.
Semantic dementia (SD), also known as the semantic variant of PPA (svPPA) affects a person’s ‘semantic memory’, which is the store of knowledge that we gain throughout our lives about the world we inhabit – who people are, what objects are, and what words mean. In other words, a person with semantic dementia gradually losses their meaning or understanding of words, for example, if you said to somebody with semantic dementia “Please pass me the scissors”, they might reply, “What are scissors?” This change is called anomia. People with svPPA can continue to speak quite fluently – but they may use more general words, for example saying “bird” rather than a specific name, or omit words, which may make it difficult for others to understand them. They may also have difficulty recognizing objects or faces, known as prosopagnosia, as well as changes in behaviour and personality, as seen in people who develop behavioural variant FTD.
Logopenic aphasia (LPA), also known as the logopenic variant of PPA (lvPPA) affects word finding ability, that is, a person with lvPPA might have difficulties searching for the right word to say, although their ability to physically produce speech is not affected neither is their understanding of the meaning of words. Compared to someone with nfvPPA, speech in lvPPA is not physically difficult, rather these word-finding difficulties lead to less spontaneous speech, long pauses in conversations as they search for the right word. People with lvPPA can also get parts of words muddled up, for instance saying “aminal” instead of “animal”. Their working memory, that is our ability to process, utilize and remember information daily, can also be affected. When this happens, people with lvPPA experience difficulties with repeating sentences and phrases as well as understanding complex sentences, for example, instructions.
PPA is very rare and usually starts between the ages of 50 and 70. However, it can also affect older people and rarely, younger people as well. Many people describe long and frustrating journeys through different medical professionals before receiving a diagnosis. Even then, many people will not be told which subtype of PPA they are likely to have. Others will be told that whilst they clearly have a type of PPA, their symptoms don’t neatly match to one of the three major variants described here. This is because there is a great deal of overlap in symptoms or clinical features of the FTD and PPA variants, such as with language, speech, behaviour and motor or movement difficulties, for example swallowing.
We also do not yet fully understand what causes these diseases. What we do know is that proteins, which maintain and support brain cells, stop working healthily and this damage produces the changes seen in people with PPA. For nfvPPA and svPPA, there are usually the same proteins that cause frontotemporal dementia, whilst in lvPPA, it is usually caused by problems with the same proteins seen in Alzheimer’s disease. Some people refer to lvPPA as an unusual or atypical form of Alzheimer’s disease. Key questions remain as to why these proteins stop working and cause damage in certain areas of the brain, and why (and how) they particularly affect the language system in the brain. In rare cases, PPA can be genetic, meaning that a specific faulty gene might be causing these proteins to stop working in the way that they should. This is only the case for a small minority of people with PPA. If you have a genetic form of PPA it may also be referred to as familial frontotemporal dementia (fFTD).
To diagnose PPA, a neurologist will usually conduct several assessments to determine whether the person is having difficulties with language more than with anything else – for a diagnosis of PPA, problems with language must be the first and most obvious symptoms. Next, they will need to determine whether the person’s language problems are caused by PPA, or by something else. To do this, they will ask for a detailed history: what difficulties is the person having, and when did they start? Ideally, they will ask the same questions of someone who knows the person well.
A neuropsychologist may also assess how exactly a person’s language is affected. For example, is it their ability to produce speech, problems finding the right word to say, their understanding of words, or a combination of all three? An MRI brain scan can also be helpful – this allows the neurologist to see a picture of the inside of the person’s brain – and they can look for any areas that show signs of damage. As most people’s language systems are in the left side of their brain, the neurologist might look for changes here, and specifically within the frontal and temporal lobes that are known to be affected in PPA. Sometimes, the neurologist might ask for a lumbar puncture or “spinal tap”. The fluid that can be taken in this way is the same fluid that flows around in our brains – and so analysing this fluid can give an indication as to whether the person’s PPA might be caused by the same proteins that cause typical Alzheimer’s disease.
Currently, there is no cure for PPA. However, there are various evidence-informed strategies and interventions to improve or maintain language and speech as well as motor/movement abilities. Speech and language therapy can help people living with PPA and their families better manage communication difficulties. It has also been found effective in managing problems with swallowing and diet.
Pharmacological treatments might also be helpful, to manage behavioural changes or in instances where a person’s PPA is caused by the same proteins that cause typical Alzheimer’s disease, such as in logopenic aphasia, they may benefit from medicines, called cholinesterase inhibitors, which alleviate symptoms in Alzheimer’s disease. Treatments might also be helpful to manage symptoms of depression or anxiety due to loss of speech and language abilities, including referral to a mental health professional where needed.