What is Primary Progressive Aphasia?
Aphasia is a condition that affects a person’s ability to understand and use language, and it’s caused by damage to specific areas of the brain. One type of this disorder, called Primary Progressive Aphasia (PPA), is actually a group of diseases that result in slow, gradual issues with speech and language. These diseases are unique because they primarily affect language skills, without significantly impacting thinking abilities, physical health, or behavior. Classic aphasia typically happens suddenly (such as after a stroke), but PPA develops slowly over time.
Thanks to ongoing research, we’re now better at identifying and differentiating PPA from other disorders based on their language profiles. We also have advanced brain imaging techniques, like diffusion-weighted imaging (DWI) and resting-state functional magnetic resonance imaging (fMRI), to study PPA in more detail. These techniques offer insights into how PPA affects the brain’s structures and functions. However, we still don’t fully understand its pathology, and the exact cause is yet uncertain. Despite this, the improved characterization of PPA helps doctors manage the disease more effectively.
There are two types of aphasia based on their symptoms – fluent and nonfluent. Fluent aphasia is associated with comprehension difficulties and is usually linked to damage in the Wernicke brain area. Nonfluent aphasia, on the other hand, is characterized by difficulties in expressing language verbally or in writing, and is often linked to damage in the Broca brain area. The idea of a disorder causing progressive language impairment without cognitive effects was first proposed in the 1890s, but it was Mesulam in the 1980s who explored this concept in detail and gave it the name “slowly progressive aphasia.” This was later renamed to “primary progressive aphasia.”
PPA is closely related to Alzheimer’s disease and Pick’s disease, making its classification and diagnosis sometimes a bit controversial. It has three main types: nonfluent/agrammatic (nfvPPA), semantic (svPPA), and logopenic (lvPPA). PPA presents in quite a similar way as primary progressive apraxia, which is a slow, degenerative disorder affecting the planning, programming, and execution of speech commands.
The brain areas that are primarily affected by PPA are those related to language. These brain areas vary depending on the type of PPA, but commonly affected regions impact the left-hemisphere language functions. For instance, the Broca area in the posterior portion of the left inferior frontal gyrus, which is responsible for language production and grammar. The Wernicke area within the posterior aspect of the left superior temporal gyrus is in charge of language comprehension. Damage to these areas can lead to serious language problems, including word-finding and semantic knowledge deficits.
Damage to other areas of the brain, like frontal lobes, especially the left inferior frontal gyrus, can result in nonfluent or agrammatic speech as they are involved in language production, grammar, and articulation. Parietal lobes contribute to language processing, especially in reading and semantic comprehension, so damage to these regions can further impede language comprehension and processing. It’s worth noting that in some patients with PPA, damage may occur in other language-related brain areas, affecting their reading and comprehension abilities. Understanding the brains areas affected by PPA is key in diagnosing the disorder, estimating the patient’s prognosis, and developing therapies tailored to the patient’s unique language issues and affected brain areas.
What Causes Primary Progressive Aphasia?
Primary Progressive Aphasia, or PPA, is a group of disorders that progressively harm the area of the brain responsible for language. It is usually classified as a type of Frontotemporal Dementia (FTD), a broad term for different types of dementia that affect the front and sides of the brain. Since 2011, this has been categorized into two main types, the more common behavioral variant (bvFTD) and Primary Progressive Aphasia (PPA).
There are three different subtypes of PPA, each affecting different areas of the brain. The first two, semantic and nonfluent variants, are linked to FTD, while the third, the logopenic variant, is more like Alzheimer’s disease. The semantic variant mainly affects the front part of the temporal region of your brain. The area affected by the nonfluent variant is the lower frontal gyrus and precentral cortex (the back and lower middle parts of the brain). The logopenic variant affects the left back upper and middle sections of the temporal lobes and the bottom of the parietal lobe.
The Nonfluent or Agrammatic PPA variant is most commonly linked with a protein associated with FTD known as FTD-4R tau. Other reports suggest a TDP-43-A pathology in some patients, as well as mutations in specific genes. Alzheimer’s disease has also been reported in some patients with this PPA variant.
The Semantic PPA variant is almost always associated with pathological aggregates found in most cases, called TDP-43-C. This variant is often connected to FTD tau in the rest of the patients.
The Logopenic PPA variant is most often caused by Alzheimer’s disease pathology in around 95% of cases. This condition is recognized as one of the potential early presentations of Alzheimer’s disease, although other pathological profiles such as Lewy body dementia, TDP-43, and tau have been also reported.
Risk Factors and Frequency for Primary Progressive Aphasia
Primary Progressive Aphasia (PPA) is quite rare, affecting roughly 3 to 4 people out of every 100,000. To put it into perspective, a study showed it occurs about 1.14 times per 100,000 person-years, which is significantly lower than the 35.7 times for Alzheimer’s disease. As for nfvPPA’s prevalence, it is even rarer, affecting about 0.5 to 3.9 people out of every 100,000.
PPA isn’t more common in either sex; it affects both men and women equally, typically around the age of 60. It’s important to note that there are no known risk factors tied to demographics, the environment, or socioeconomic status.
Of those who have PPA, between 56% and 86% also have speech apraxia, a condition affecting the motor skills needed for speech. Interestingly, a recent study highlighted that while the behavioral variant of Frontotemporal Dementia (bvFTD) is more common in men, PPA tends to affect women more frequently.
Signs and Symptoms of Primary Progressive Aphasia
Primary progressive aphasia (PPA) is a condition where people gradually lose their ability to speak and understand language. It’s different from other forms of dementia because language problems usually happen early on instead of later. It continues to get worse over time, unlike an acute stroke which happens suddenly and doesn’t get worse.
Doctors diagnose PPA by examining a patient’s ability to understand language, express themselves, and their fluency in written and verbal communication. They also check memory, executive function, and spatial abilities to rule out other degenerative brain disorders. Motor function, sensation, and reflexes are also evaluated to make sure there are no other neurological conditions that could look like PPA.
The disease can come in different forms, each with their own signs and symptoms.
The nonfluent/agrammatic variant (nfvPPA) features painstakingly slow and grammatically incorrect speech. Other cognitive abilities like attention, memory and executive functions may also decline over time. Behavioral changes could also occur.
People with the semantic variant (svPPA) gradually have a harder time understanding and using words correctly. This leads to problems retrieving words and understanding single words. As the disease progresses, patients may have difficulty with recognizing objects. They can also struggle with concrete concepts more than abstract ones.
The logopenic variant (lvPPA) presents with difficulty finding words and repeating sentences. As the disease gets worse, sentence comprehension is impaired. These patients may experience cognitive decline faster, affecting language and spatial abilities.
- nfvPPA: Slow, grammatically incorrect speech. Mild cognitive decline and behavioral changes.
- svPPA: Problems with word retrieval and understanding single words. Difficulty recognizing objects and struggle with concrete concepts.
- lvPPA: Difficulty finding words and sentence repetition. Rapid cognitive decline.
Testing for Primary Progressive Aphasia
If your doctor suspects you have Primary Progressive Aphasia (PPA), a condition that affects your ability to communicate, they will start by getting a detailed history from you and performing specific speech and language tests. There are several types of this disorder, and doctors use a two-fold approach to identifying the right one. First, they see if you meet the criteria established by a doctor named Mesulam. After that, they use diagnostic features identified by Gorno-Tempini to determine the particular type of PPA you have.
One key assessment includes the Northwestern anagram test, which examines how well you can use grammar. Often, patients with a type of PPA called nonfluent/agrammatic variant PPA (nfvPPA) struggle with this test. Another useful evaluation is the Montreal Cognitive Assessment test, which helps doctors assess cognitive decline and differentiate it from dementia. However, this test must be used carefully because reduced verbal output, Apraxia of Speech (AOS – a motor speech disorder that makes it hard to speak), and depression can all lower the test results. Taking all into account, proper speech, language, and cognitive assessment is crucial for the correct PPA diagnosis. It also helps clinicians monitor how the disease progresses and to understand the symptoms better.
Brain imaging can add to the diagnostic process, too. For example, Fludeoxyglucose positron emission tomography (FDG-PET) is often used alongside brain MRI to examine primary progressive aphasias more effectively. Certain parts of the brain, such as the Broca area and insular cortex, are more likely to be affected in nfvPPA, although usually, there is no substantial reduction in brain metabolism in the temporal and parietal areas.
Different types of PPA will present different findings on imaging studies like brain MRI and FDG-PET scans. For example, patients with nfvPPA often show more shrinkage and lower metabolism, primarily affecting the area of the brain responsible for dominant language processing. Brain MRI is not as sensitive in catching this particular condition, but it is specific in its diagnosis.
On the other hand, in Semantic variant PPA (svPPA), the brain MRI and FDG-PET show shrinkage and lower metabolism in the front part of the brain’s temporal lobes. For this type of PPA, imaging can be extremely helpful in diagnosis. It is both sensitive and specific to this condition, meaning it’s good at catching real cases and avoiding false positives.
Last but not least, for patients with Logopenic variant PPA (lvPPA), the brain damage is usually located in the posterior superior and middle part of the temporal lobes and inferior parietal lobule. However, brain MRI is not very sensitive in catching this variant but reasonably specific. FDG-PET scans, though, are both highly sensitive and specific, making them a great tool in the diagnosis of lvPPA.
Treatment Options for Primary Progressive Aphasia
Currently, no medicines have been found to be effective for Primary Progressive Aphasia (PPA), a neurological syndrome that affects language capabilities. The best way to manage this condition is by first meticulously examining the patient’s language and speech history. This contradicts earlier thoughts that speech and language therapy didn’t help much. Hence, a referral to a speech and language specialist is crucial for correctly identifying language issues and working out the best treatment plan. It’s proven that speech and language therapy is the most successful way to manage PPA, particularly for motor speech issues.
In addition to this, transcranial direct current stimulation, a treatment that uses a simple electric current to stimulate specific areas of the brain, is viewed as a hopeful strategy to improve the results of language therapy in PPA patients. Its affordability, safety, and non-invasive nature make it worth researching its potential to boost behavioral solutions and slow down language deterioration in PPA.
What else can Primary Progressive Aphasia be?
When a doctor is considering Primary Progressive Aphasia (PPA), they need to make sure other conditions with similar symptoms are not the actual source of the problem. These conditions include:
- Dementia: A person might show signs of language loss (aphasia) as part of dementia. However, with PPA, aphasia is always the first and key symptom.
- Ischemic Aphasia: Affected individuals might suddenly show signs of aphasia due to restrained blood flow (ischemia). PPA, on the other hand, progresses gradually over many years.
- Brain Tumor: A tumor in the brain areas responsible for speech could lead to progressive aphasia as it grows. Additional symptoms could include a headache or weakness in the senses and movements, which don’t usually occur in PPA. Brain imaging can help distinguish a tumor from PPA.
- Alzheimer’s Disease: This condition primarily shows signs of dementia at the beginning. PPA differs in the sense that it has aphasia as the main symptom in the early stages and does not usually involve dementia.
- Frontotemporal Dementia (FTD): FTD initially presents with dementia, while PPA begins with aphasia. Although dementia may develop later in PPA, it is not an initial symptom.
To effectively determine if the condition is PPA, a doctor needs to conduct a thorough history analysis, physical examination, and appropriate diagnostic tests.
What to expect with Primary Progressive Aphasia
Primary Progressive Aphasia (PPA), a condition that affects a patient’s speech and language abilities, is progressive and, unfortunately, there is currently no cure. This means that over time, individuals with PPA will gradually lose their ability to speak and understand both written and spoken language. Initially, the most common symptoms of PPA are related to problems with speech (aphasia) and difficulty carrying out movements (apraxia).
As the condition progresses, other cognitive and behavioural issues may develop. However, these changes usually only start to occur 8 to 12 years after the first symptoms emerge. It’s hard to predict the exact progression of PPA in each individual because the disease varies greatly from one person to another.
Typically, most people with PPA live for anywhere from 3 to 12 years after their diagnosis. On average, different forms of PPA have different average life spans – semantic variant PPA (svPPA) is approximately 12 years, nonfluent variant PPA (nfvPPA) is around 7.1 years, and logopenic variant PPA (lvPPA) is about 7.6 years. The most common cause of death for people with PPA is aspiration pneumonia, a lung infection that can occur when food, drink, or saliva is inhaled into the lungs.
Possible Complications When Diagnosed with Primary Progressive Aphasia
: People with PPA may face complications such as:
- Inability to speak and write
- Difficulty in understanding written or spoken language
- Depression
- Poor decision-making ability
- Improper social behavior
- Rare occurrences of Parkinsonism, abnormal reflex responses, and corticobasal syndrome.
To manage these complications, we need a team of specialists. This team should include speech and language therapists, cognitive rehabilitation specialists, psychosocial support staff, and caregiver educators. These professionals will help improve the quality of life and care for the patient.
Preventing Primary Progressive Aphasia
Preventing PPA, a type of brain illness, often centers on reducing the chances of getting diseases that can cause harm to the brain, and on promoting overall brain health. These steps may involve living a healthy lifestyle, which can include a balanced diet, regular physical activity, and brain training exercises such as reading and puzzle-solving. It’s also important to manage heart-related health risks, like high blood pressure, diabetes, and obesity. This is because the health of your heart can influence the health of your brain. Additionally, trying to prevent head injuries and maintaining social relationships can help to keep your cognitive abilities sharp and reduce the risk of declining mental function.
Alongside these preventative measures, early detection and management of other health conditions that may contribute to cognitive decline can help slow down PPA’s progress. If you notice memory loss or difficulties with language, it’s beneficial to seek medical advice promptly as this can lead to early diagnosis and treatment. Regular medical check-ups and screenings can also help to detect and manage health risks such as hypertension, diabetes, and high cholesterol.
Patients with PPA and their families may face a higher risk of depression, partly due to the condition often starting at an earlier age and typically worsening over time compared to Alzheimer’s disease. Patients being aware of their condition can additionally worsen mental distress. Psychologists can evaluate, educate, and provide supportive therapy sessions to help patients and their families manage their expectations better, develop coping techniques, and receive emotional support. Since there’s no cure, they may need social help for daily activities. Getting early help with suitable treatment and support services can improve the quality of life for both people living with PPA and their caregivers.
