What is Primary Progressive Aphasia?

Primary progressive aphasia (PPA) is a type of dementia, which is a progressive cognitive decline that interferes with everyday activities and is not due to another mental disorder. The most prominent symptoms are deterioration in language processing, reading, writing, semantic knowledge, and the ability to pronounce words correctly (Nickels & Croot, 2014). The onset of the disorder is not marked by any acute neurological event, but instead the disorder begins with subtle language difficulties that often only the patient and their family members are able to detect. Originally described by researchers in 1982, the disorder is characterized by a gradual increase in the amount and severity of aphasic symptoms without much impact on non-language abilities such as memory, reasoning, insight, and judgment for at least two years of post-onset of symptoms (Thompson et al., 1997).

A clinical assessment by a neurologist remains the most accurate way to diagnose PPA. There are three inclusion criteria for a diagnosis: first, the most prominent clinical feature is difficulty with language. Second, language difficulties should be the principle cause of impaired daily living activities. Third, aphasia, which is a difficulty with language comprehension, should be the most prominent deficit at symptom onset and for the initial phase of the disease. Once the broad diagnosis of PPA is established, each individual is classified into one of three variants depending on the specific language changes. The three variants include the nonfluent, semantic, and logopenic variant. Each variant has its own constellation of symptoms, with 75-80% of patients being reliably diagnosed to a single variant (Nickels & Croot, 2014).

The language network functions to label, categorize, and communicate through the mediation of words. Damage to any part of the language network can greatly interfere with word usage and word finding. Impaired object naming and word finding are considered anomic deficits, which emerge almost universally in the early stages of PPA. Many patients remain in an anomic phase throughout their disease and experience a progression of severity in word finding deficits to the point of nearly mutism. In the anomic stage, patients who are unable to name objects that they are shown can point to the appropriate object when the name is provided by the examiner. This shows that the naming deficit is “one-way” and indicates impairment at the level of lexical retrieval rather than word comprehension (Mesulam, 2001).

What are the variants of PPA and how do they impact language?

The first symptoms of the nonfluent variant PPA are word finding difficulties and increasing anomia, which is difficulty in recalling names of everyday objects. Next, the speech fluency is diminished and some patients begin having trouble with articulation and their output becomes halting. As the disease progresses, some individuals frequently experience progressive problems with sentence construction and syntax, thus their speech becomes agrammatic, similar to Broca’s aphasia. For example, patients’ conversational speech is characterized by significant shortage of verbs and failure to produce appropriate subject-verb agreement. They also may have impaired motor planning and sequencing of movements required for correct speech production, which is a phenomenon known as apraxia of speech. Although the end-stage of this condition is characterized by complete mutism, many patients have relative preservation of comprehension. Although no reliable therapy yet exists, a few medications and speech therapy approaches have been tried (Kertesz & Harciarek, 2014).

The semantic variant of PPA has been characterized by a progressive and multimodal loss of semantic knowledge. These patients progressively lose the meaning of words and have word finding difficulty, but retain fluency, articulation, repetition, phonology, and syntax. They often overuse closed class words, pronouns and verbs, and higher frequency nouns, reflecting lexical retrieval deficits. As the disease progresses, their speech is still considered fluent, but characterized by repetition of clichés and word salad that is usually irrelevant. Eventually work finding becomes increasingly difficult and evident and the length of connected speech becomes shorter, leading to mutism. Severe progressive anomia, impaired comprehension of single words, and patients frequently asking the meaning of words are the hallmarks of semantic PPA. As the disease progresses, early lexical semantic problems become accompanied with different forms of agnosias, which is the inability to process sensory information. The most common being visual agnosia, where the ability to correctly identify objects may be modified by factors such as the type of material and an object’s familiarity and typicality. Semantic variant is strongly associated with early behavioral and personality changes, which are eventually shown in almost all semantic PPA patients. These typically include a combination of disinhibition, irritability, increased social seeking, food cravings, lack of empathy, and mental inflexibility. Unlike patients with nonfluent variant PPA, these patients are unaware of their progressive language impairment. However, similar to the nonfluent variant, there is no specific treatment or cure (Kertesz & Harciarek, 2014).

The logopenic variant of PPA is similar to the nonfluent variant in that the speech output is slowed with frequent word finding pauses. However, logopenic variant patients do not present with agrammatism, impaired motor control of speech, or aprosodia. General semantics and single-word comprehension remain intact, especially in the early stages of the disease. The core impairment that underlies most language deficits in this variant is a phonological short-term memory deficit. Behavioral changes may also be present, such as anxiety, irritability, and agitation being the most common. According to neuroimaging, the pattern of atrophy to the brain in logopenic patients is very similar to that observed in Alzheimer’s disease. Due to this connection, treatment may be similar to those used for Alzheimer’s (Kertesz & Harciarek, 2014).

How does PPA impact other aspects of life?

PPA as well as other acquired language disorders can have a profound impact on an individual and those around them. There is often a loss of independence and self-identity, an inability to work, and social isolation. These can all lead to increased likelihood of mental illness in the patient and their caretakers. PPA has a profound impact on an individual’s ability to communicate, and in turn affects their relationships, social networks, and ability to participate in many everyday activities that require communication. Unfortunately, there is little research on how a PPA diagnosis impacts the patient. However, researchers found that over 40% of their sample of people with PPA had been treated with antidepressants since their diagnosis. It is well known that the role of the caregiver can have a negative impact on their quality of life. Researchers have found that caregivers of people with dementia reported greater impacts in their lives than caregivers of people without dementia. Those areas may include employment, mental and physical health problems, time for leisure, and family conflict (Nickels & Croot, 2014). So not only does PPA have a significant impact on a patient’s life, it also greatly impacts their caregiver’s life as well.

Kertesz, A., & Harciarek, M. (2014). Primary progressive aphasia. Scandinavian Journal of Psychology, 55, 191-201.

Mesulam, M. M. (2001). Primary progressive aphasia. Neurological Process, 49, 425-432.

Nickels, L., & Croot, K. (2014). Understanding and living with primary progressive aphasia: Current progress and challenged for the future. Aphasiolog, 28, 885-899.

Thompson, C. K., Ballard, K. J., Tait, M. E., Weintraub, S., & Mesulam, M. (1997) Patterns of language decline in non-fluent primary progressive aphasia. Aphasiology, 11, 297-321.