What Is Primary Progressive Aphasia

Introduction

Primary Progressive Aphasia (PPA) is a rare neurodegenerative disorder that largely affects language abilities and is considered a subtype of frontotemporal dementia.¹ PPA develops when the lobes of the brain shrink, (atrophy). The left side of the brain is typically affected by this condition. However, the late stages of some variants encompass damage to both sides.² The damage affects a person's ability to communicate properly and eventually, they lose the ability to understand spoken and written language. This article explores the three main variants of PPA - semantic, nonfluent, and logopenic. We delve into their unique characteristics, causes, and impact on communication. 

The clinical presentation of PPA has some overlap with other forms of dementia such as Alzheimer’s and also with Parkinson’s disease. We discuss the treatment options available for PPA and also some resources for support groups that can help find other people going through the same situation. 

Types of primary progressive aphasia

There are three main variants of PPA:

1. Semantic variant

The semantic variant of PPA (svPPA) encompasses deficits in understanding what words mean, naming objects and people and finding words when communicating with people. You can have damage on either side of the brain but as the disease progresses, svPPA affects both sides. More severe symptoms later on in the prognosis can involve behaviour and personality changes with people becoming more confused and having less empathy and awareness for other people’s emotions.³

2. Nonfluent/agrammatic variant

The nonfluent/agrammatic variant of PPA (naPPA) develops earlier on than other variants and involves disordered speech sound production and poor grammatical comprehension. The variant typically affects the left side of the brain in structures that control muscles related to the ability to form sounds such as the lips and tongue.⁴

3. Logopenic variant

The logopenic variant of PPA (lvPPA) involves impaired repetition of sentences, pronouncing words wrong, and difficulties in remembering/finding the right word. Someone with this variant can have small talk with ease but struggle with specific and unfamiliar words. Specific to this type of PPA, people can have more difficulty with longer sentences that require them to repeat phrases.⁵

Understanding primary progressive aphasia

Demographics of individuals affected by PPA

Currently, there are no estimates on the prevalence of PPA however, it is a language disorder that is often seen in neurodegenerative diseases, such as frontotemporal lobar degeneration (FTLD), where language abilities also decline over time. Current research on FTLD allows us to estimate that 20-40% of cases involve PPA. Typically, symptoms can start in the late 50s but some variants such as nonfluent PPA can start earlier. There are no environmental risks and gender also doesn’t seem to play a role in the development of the condition.⁶

Causes and risk factors associated with PPA

The two most common underlying diseases associated with PPA are FTLD and Alzheimer’s disease (AD). 30-40% of PPA cases are caused by AD and FTLD causes approximately 60-70% of cases.⁷ Importantly, AD predominantly affects memory rather than language which is why PPA is thought to be an atypical consequence when associated with AD. 

The different variants of PPA are caused by different changes in the brain. The semantic variant is caused by a build up of TDP-43 protein while the nonfluent type is a buildup of tau proteins. Logopenic aphasia is associated with a build-up of amyloid proteins which can damage the brain cells over time - this is the sample pathology that underlies AD which is why it is also considered a young onset form of this disease.⁸

The genetic manifestation of PPA is rare however it can be passed down through families. A study looking at 403 PPA cases found that only 3.5% of cases were likely caused by genetic variants.⁹ Genes such as MAPT, GRN and C9ORF72 have been implicated and are also involved in other forms of dementia.¹⁰

Clinical manifestations and impact on communication

Language is heavily affected in PPA. Because it is a progressive condition the symptoms become more severe over time. The condition typically starts mild with some common early symptoms are forgetting someone's name or finding the right word. Other symptoms include:¹¹ 

• Hesitant when speaking, making mistakes with grammar and the sounds of words 
• Having difficulty understanding other people due to forgetting the meaning of words
• Having difficulty being clear with what they’re saying, speech becoming vague 
• Speech develops into short, simple sentences and becomes slow 
• Retracting from conversations and becoming less likely to join in 
• With disease progression, changes in personality and behaviour can occur 
• Overlap with symptoms of Alzheimer’s Disease such as difficulty thinking and memory 
• Overlap with symptoms of Parkinson’s Disease, difficulties with movement
• A decline in independence and daily living from the onset of the disease 

Diagnosis and assessment

If your healthcare provider thinks you may have PPA you will likely be referred to a specialist clinic. Some other things involved in the diagnosis include:¹²

• Inquiry into your medical history and symptoms 
• A neurological examination is often conducted by a specialist in speech and language
  • Evaluation of cognitive abilities, language skills, memory, and behaviour
  • This can also measure your ability to name and recognise objects, recall words, and other factors 
• Discussions with the people close to you such as a partner or close relatives regarding the challenges you have been experiencing with speech and language 
• Brain imaging, typically an MRI scan 
• Potential other tests such as genetic tests using a lumbar puncture or blood tests
  • Blood tests can help health care providers to see if there are any other infections present or other medical conditions 
  • Genetic testing can help look at the underlying genetic changes associated with PPA, lumbar puncture helps to examine protein levels in the cerebrospinal fluid 

Treatment and management

Speech and language, and cognitive therapies 

Unfortunately, there is no cure for PPA much like there is no cure for any form of frontotemporal dementia. It has been estimated that on average, people with PPA survive for about 7 years but this can differ with the type and severity of PPA.⁶  While there is little evidence to suggest that speech and language therapy can slow down the progression of the condition, it can help to manage the symptoms. Some people with PPA are referred to a physiotherapist, dietitian, or occupational therapist to help improve their quality of life. As well as this, cognitive therapy is commonly used to treat people with dementia as it is associated with improvements in memory and thinking skills. This involves playing games typically in a group and has a focus on engaging people with dementia and enjoyment.¹³ 

The current research on speech therapy for treating all subtypes of PPA focuses on addressing word retrieval. Language therapy has been associated with positive outcomes including the potential for learning new words when affected by the condition. There is also evidence to suggest that benefits gained from therapy can be maintained. However, the long-term effects are not yet studied in detail, and those that have, see variable outcomes.¹⁴ 

Transcranial direct current stimulation 

Several studies have explored the use of transcranial direct current stimulation to enhance language abilities or slow the decline of language skills. While positive outcomes are generally observed across different studies, there is considerable variation depending on the population of patients, the location of stimulation and the subtype of PPA.¹⁵ 

Treatment of other symptoms 

People with the semantic variant of PPA are sometimes prescribed selective serotonin reuptake inhibitors (SSRIs) to help with the behavioural changes associated with this particular subtype. In previous years, SSRIs have been beneficial in treating psychiatric patients that resemble some of the problematic behaviours exhibited in late-stage svPPA¹⁶. Other symptoms, such as depression, are commonly seen in all types of dementia and PPA is no exception¹⁷. Consulting with clinicians about various types of therapies and medication can help people develop different ways of thinking and behaving to alleviate symptoms of low mood. 

Support groups

It can be useful for both individuals and caregivers to refer to support groups to meet like-minded people going through the same situation. 

• There is a national PPA support group that holds meetings throughout the year in London to support people living with PPA: www.raredementiasupport.org/primary-progressive-aphasia
• For a younger demographic, the Young Dementia Network supports people under 65 with many different types of dementia: www.youngdementianetwork.org

Summary 

In summary, PPA can have hugely detrimental effects on a person’s ability to communicate. The disease is progressive and while there is no cure, there are some resources that can help manage the symptoms and improve quality of life. Speech and language therapy, cognitive therapy and transcranial direct current stimulation show promise in addressing language-related challenges. Continued research into the long-term effects of therapies and the exploration of emerging treatments will contribute to a better understanding of PPA and enhance the care and support available to those affected by this unique form of dementia.