Clinical Perspectives on Primary Progressive Aphasia

Lyndsey Nickels, Karen Croot, Lyndsey Nickels, Karen Croot

• Publisher: Psychology Press
• Year: 2017
• ISBN:
  9781317525752
• Edition: 1
• Topic: Psychology
• Subtopic: History & Theory in Psychology
• Index: Psychology

Primary progressive aphasia is a type of dementia that progressively impairs language abilities (speaking, understanding, reading and writing) and may eventually affect other aspects of thinking, movement and/or personality. For the person with primary progressive aphasia, these problems have a profound effect on their ability to communicate, which in turn impacts their relationships, social networks and ability to participate in everyday activities that depend on communication. Recent understanding of primary progressive aphasia has grown enormously, however, and this book provides an up-to-date survey of research relevant to the clinical care of people with primary progressive aphasia. It covers initial diagnosis, neuropathology, genetics and typical patterns of progression from early- to late-stage disease, with a special focus on management and intervention for a range of different language symptoms and everyday communication activities.

This book is suitable for a wide readership, from neurologists, geriatricians and other medical specialists, to general practitioners, speech and language therapists, occupational therapists, psychologists and students in these fields. It was originally published as a special issue of the journal Aphasiology.

Understanding and living with primary progressive aphasia: Current progress and challenges for the future

Lyndsey Nickels^1,2,3 and Karen Croot^2,3,4

¹Department of Cognitive Science, Macquarie University, Sydney, Australia
²ARC Centre of Excellence in Cognition and its Disorders (CCD), Macquarie University, Sydney, Australia
³NHMRC Centre of Clinical Excellence in Aphasia Rehabilitation, Australia
⁴School of Psychology, University of Sydney, Sydney, Australia

Background: Primary progressive aphasia (PPA) is a progressive language disorder in which aphasia is the first and most prominent symptom of degenerative brain disease. PPA has received increasing attention in the scientific literature over the past 30 years, but there remains a relative lack of awareness and understanding of it in the wider clinical community. As editors of the volume, Clinical Perspectives on Primary Progressive Aphasia, we invited the contributing authors to provide an up-to-date survey of research on a range of topics that are relevant to clinical practice in PPA.

Aims: The aim of this article is to address some key questions that may arise when an individual receives a diagnosis of PPA and to direct readers to additional sources of information in this volume and elsewhere that will allow them to gain further knowledge about topics of interest.

Main Contribution: We address the following questions: (1) What is PPA? (2) How is PPA diagnosed? (3) What happens to a person’s language when they have PPA? (4) How will the disease progress over time? (5) How does PPA impact a person’s life and the life of their family and friends? (6) What treatments and support are available? (7) What other services should we be providing?

Conclusions: Considerable progress has been made in our understanding of PPA and the relationship between the symptomatology, progression, pathology, and genetics of PPA. However, there are many challenges remaining, particularly in terms of ensuring that people with PPA and their families and friends receive optimal information and support at diagnosis and appropriate interventions and/or management strategies throughout their journey with PPA.

Primary progressive aphasia (PPA) is a type of dementia: a progressive cognitive decline that interferes with everyday activities and is not due to another mental disorder (Diagnostic and statistical manual of mental disorders, fifth edition (DSM-5), American Psychiatric Association, 2013). The most prominent symptom is deterioration in language processing, reading, writing, or semantic knowledge. It occurs in people who are typically in their late 50s or older, but cases have been reported from as early as 20 years of age to 80 years and upwards. Receiving a diagnosis of PPA is devastating for the person with PPA and those close to them. Diagnosis leads to many questions like “What is primary progressive aphasia?”, “How do you know I have it?”, “How did I get it?”, “What can I expect next?”, and “Is there anything that can be done?”. Thirty years ago, we were just beginning to recognise PPA as a separate clinical entity (Mesulam, 1982), and we did not know the answers to these questions. While there are still many unknowns, our understanding has grown immensely over this time, and those of us working clinically with people with PPA are now able to provide at least some answers. In this article, we consider some of the questions that might be asked by people with PPA and the clinicians involved in their care: We review current understanding and challenges that remain to be addressed in future research, and we direct readers to additional sources of information in this volume and elsewhere that will allow them to gain further knowledge about topics of interest.

WHAT IS PRIMARY PROGRESSIVE APHASIA?

As noted earlier, PPA is a type of dementia. However, while dementia is often associated with changes to memory, behaviour, and/or a range of other cognitive abilities, the primary early symptom in PPA is a relatively selective deterioration in language processing. People with PPA frequently have problems in retrieving the words they need to communicate (anomia), but the initial symptoms may also be in reading, writing, grammar, semantic knowledge, or the ability to pronounce the sounds of words correctly. PPA occurs due to one of two types of neuropathological changes that affect the language areas of the brain: frontotemporal lobar degeneration pathology or Alzheimer-type pathology (Gorno-Tempini et al., 2011; Grossman, 2014). Our understanding of these neuropathological changes is advancing: When frontotemporal lobar degeneration is the cause of PPA, there is an abnormal accumulation of one or the other of two different kinds of protein in the brain cells: TDP-43 or tau (for further discussion, see Grossman, 2014). When PPA is caused by Alzheimer’s disease pathology, it is possible that this is a distinct subtype of Alzheimer’s disease: Mesulam et al. (2014) argue that the Alzheimer’s disease that causes PPA is biologically, anatomically, and clinically distinct from the typical late-onset Alzheimer’s disease.

It is challenging to estimate how common PPA is (Knopman & Roberts, 2011). As Grossman (2014) notes, there are no community-based surveys of its frequency. However, reasoning that around 40% of cases with frontotemporal lobar degeneration in autopsy studies had PPA, Grossman estimates that between 1 and 6 people per 100,000 will have PPA due to frontotemporal lobar degeneration at any one time, with additional people having PPA due to Alzheimer’s disease pathology. This equates to upwards of 8,000–44,000 people with PPA in Europe; 700 and 4,000 people in the US, and 250–1,400 people in Australia.

HOW IS PPA DIAGNOSED?

Clinical assessment by a neurologist with expertise in PPA remains the most accurate way to diagnose PPA. The international criteria for diagnosis and classification of PPA (hereafter called International Consensus Criteria, Gorno-Tempini et al., 2011) base the initial diagnosis of PPA on Mesulam’s (2001) criteria. There are three inclusion criteria (Gorno-Tempini et al., 2011, Table 1, p. 1008):

(1) The most prominent clinical feature is difficulty with language.

(2) Language difficulties are the principal cause of impaired daily living activities.

(3) Aphasia should be the most prominent deficit at symptom onset and for the initial phases of the disease.

In addition, the International Consensus Criteria include four exclusionary criteria. In order for the diagnosis to be PPA:

(1) The pattern of deficits cannot be better accounted for by other nondegenerative nervous system or medical disorders.

(2) The cognitive disturbance cannot be better accounted for by a psychiatric diagnosis.

(3) There are not prominent initial episodic memory, visual memory, and visuoperceptual impairments.

(4) There is not a prominent, initial behavioural disturbance.

Once the broad diagnosis of PPA is established, Gorno-Tempini et al. (2011) advocate that each case is classified into one of three PPA variants depending on the specific language changes (see below), also following the International Consensus Criteria (see Leyton & Hodges, 2014, for a heuristic to assist with diagnosis of specific PPA variants). The three variants advocated by the International Consensus Criteria are the nonfluent/agrammatic variant (nfvPPA), the semantic variant (svPPA), and the logopenic variant (lvPPA). The diagnosis of each PPA variant can be made at one of three levels. At the clinical level, diagnosis is made using behavioural criteria based on the particular language symptoms that are present. At the second, imaging-supported level, diagnosis is made using a combination of behavioural criteria and brain imaging data identifying atrophy or reduction in metabolism/blood flow in specific brain regions. The third level is that of a definite pathological diagnosis. At this level, cases must have a clinical classification of the particular variant (with or without neuroimaging evidence) and either confirmation of pathology (see Grossman, 2014) or confirmation of genetic mutations associated with a particular aetiology (see Rohrer, 2014). Gorno-Tempini et al. (2011) note that the presence of confirmed pathology does not imply that the clinical description of the syndrome is any better, rather that the clinical features have been associated with a known biological feature.

The three variants can be reliably diagnosed in around 75–80% of individuals: Leyton and Hodges (2014) note that as many as 20% of cases may not fit neatly into the International Consensus Criteria variants, which still therefore pose a diagnostic dilemma. Similarly, Mesulam et al. (2014) found that 23% of their PPA cases were unclassifiable under the International Consensus Criteria, while others met the criteria for more than one subtype. Moreover, there were changes over time in subtype classification, which was particularly evident for the logopenic variant (7 of the 11 participants who were initially diagnosed with logopenic variant PPA progressed to either agrammatic/nonfluent variant PPA, semantic variant PPA, or mixed PPA by the second visit).

In sum, the International Consensus Criteria Statement is not without its critics. However, terminology and subtyping have varied from research group to research group in the past (for review, see Croot, Nickels, Laurence, & Manning, 2009; Leyton & Hodges, 2014), and the advent of the International Consensus Criteria makes it likely that diagnostic labels will be used more consistently.

WHAT HAPPENS TO A PERSON’S LANGUAGE WHEN THEY HAVE PPA?

The majority of people with PPA will share a common symptom of word finding difficulty (Jokel, Graham, Leonard, & Rochon, 2014; Mesulam, 2001). Nevertheless, regardless of the variant they have, the clinical symptoms vary from person to person just like they do in acute-onset aphasia due to stroke. Indeed, Léger and Johnson (2007) suggest that compared to acute-onset aphasia, the clinical symptoms are more variable in PPA because the brain damage in PPA is less severe (at least initially) and more widespread. Similarly, Mesulam (2001) notes that the language changes in PPA also rarely fit the “classical” syndrome subtypes (Broca’s aphasia, Wernicke’s aphasia, conduction aphasia, and so on) that have been so widely used to classify acute-onset aphasia.

The clinician (usually a neurologist, geriatrician, psychiatrist, or speech and language pathologist) will take a detailed history and request a brief clinical evaluation of a number of language domains. This is important not only to identify the particular variant of PPA (Gorno-Tempini et al., 2011) but also to understand the nature of the language and communication problems that will be experienced by the individual. Evaluation of language should ideally be performed by a speech and language pathologist, for greatest reliability. The language domains to be evaluated are various features of speech production (grammar, motor speech, sound errors, and pauses due to impaired word finding), repetition of words and sentences, single-word and sentence comprehension, picture naming, semantic knowledge, and reading/spelling. While establishing the PPA variant will be a useful shorthand for communication between clinicians, it is likely to be more informative for management and intervention to specify the particular pattern of impaired and retained language functions individually for each person with PPA (for ideas on how to achieve this, see Sapolsky, Domoto-Reilly, & Dickerson, 2014).

People with PPA experience difficulties in comprehending language. In semantic variant PPA, this is due, in the first instance, to a deterioration in semantic memory, our encyclopaedic knowledge of the world, of facts and word meanings (Hodges, Patterson, Oxbury, & Funnell, 1992), which impacts comprehension of spoken and written words (Faria, Sebastian, Newhart, Mori, & Hillis, 2014). In logopenic variant PPA, there can also be difficulties in auditory word comprehension, but problems retaining linguistic information in working (short-term) memory (Gorno-Tempini et al., 2008) also may contribute to difficulties in understanding spoken and written language. In nonfluent/agrammatic variant PPA, there may be difficulties understanding grammatical morphology, verbs and verb argument structure, and morphosyntax (Thompson & Mack, 2014).

As noted earlier, in speech production, word retrieval impairments are common to the vast majority of people with PPA (Jokel et al., 2014). In contrast, grammatical impairment is usually absent in logopenic variant PPA (lvPPA) (Thompson, Ballard, Tait, Weintraub, & Mesulam, 1997) but is characteristic of the nonfluent/agrammatic variant (nfvPPA), where production of grammatical morphology, verbs and verb argument structure, and morphosyntax is impaired (Thompson & Mack, 2014). Importantly, however, not all individuals with nfvPPA have prominent grammatical impairments—some have motor speech impairments (apraxia of speech, dysarthria) in ...