Primary Progressive Aphasia

Recent Research:•Differential Diagnosis•Problems Regarding present Model •Implications for Management

Rachel Kennedy, SLT

Overview - Introduction & Evolving Definitions - Introduction to Variants - Differential Diagnosis from a Language

Perspective- Problems Regarding Present Definitions - Implications for Management - Conclusions & Questions

Primary Progressive Aphasia: A Basic Definition

Associated with Fronto-Temporal Dementia (Harciarek et al, 2014)

“A clinical condition characterised by a gradual, progressive loss of specific language functions with relative preservation of other cognitive faculties and independence over approximately the first two years from onset” (Mesulam, 2001)

Primary Progressive Aphasia: A Potted History

Concept first introduced by Pick and Serieux in the 1890’s (Bonner et al, 2010) Mesulam’s report in 1982 placed PPA on the radar for modern neurological studies Insidious onset, gradual progression, prolonged course; presumably due to focal impairment of left peri-sylvian region of brain (Duffy, 1987) Characterized by gradual dissolution of language without impairment of other cognitive domains for at least first two years… (Taylor et al 2009)Part of an evolving understanding of neurodegenerative conditions affecting cognitive functions other than memory or behaviour

Just Primary Progressive Aphasia – or sub classes within the diagnosis?

“Tripartite model” first proposed by Gorno-Tempini et al in 2011

Each associated with a specific pattern of speech and language deficits…

Based on cross-sectional data rather than longitudinal observation

With different distributions of atrophy on neuroimaging

Non-fluent/agrammatic variantDysfluent, effortful speech with hesitations, errors and

retakes in production of speech sounds; speech rate a third to a half of that of healthy speakers

Reduced length of utterances in connected speech, less complex sentences, grammar errors

Dysarthria and apraxia of speech may also feature/contribute

Reduced grammar comprehension at a complex level Naming difficulty less severe than other 2 defined

variants, affected by phonological assembly difficulty

nfvPPA – Language HallmarksLow fluency scoresLow grammar scoresWord comprehension

superior to sentence comprehension

Naming better preserved than fluency

Semantic VariantFluent variant associated with frontotemporal lobar

degenerationDifficulty with confrontation naming for pictures, objects;

category naming, fluency. Reduced knowledge of uses and features of objects

Reduced single word comprehension, reduced receptive language skills

More obvious with lower frequency target words or conceptsOver use of general referent words e.g. “that” “thing” Surface Dyslexia – reading words out phonetically. May write words phonetically also e.g. “yot” for yacht Behavioural Changes as progresses

SvPPA – language hallmarks Defective auditory

recognition of names of body parts; better with colours, letters and numbers (Harciarek & Kertesz, 2009).

Patients may question meaning of words heard in conversation

Poor on semantic fluency and naming

Preserved repetition, up to multisyballic words and sentences

Logopenic Variant Slowed spontaneous speech output, WFDs and phonemic paraphasias Good grammar, good motor control of speech Reduced auditory verbal short term memory; less good with sentence repetition, digit, word and letter span therefore Reduced receptive verbal language, not improved with simple language LVPPA frequently assoc with characteristics of Alzheimer’s due to reduced episodic memory; better than AD pts however with single word recognition & semantics (comprehension tasks). Core impairment seems to be in PHONOLOGICAL LOOP FUNCTION (auditory verbal STM). Accounting for reduced repetition, speech comprehension.

LvPPA – language hallmarksParaphasias disrupt

fluencyDeficient namingDefective repetition of

sentencesApraxia of speech (not

seen in logopenic)

Diagnostic Indicators: Building a Language Profile Useful Assessments from SLT – Standardized Language Batteries Comprehensive Aphasia Test (CAT, 2004), Western Aphasia Battery (WAB, 2007) Domain Specific Formal Assessments Boston Naming Test (BNT), Psycholinguistic Assessments of Language Processing in Aphasia (PALPA, 1997), Pyramids & Palm Trees (1992), Test for Reception of Grammar (TROG, 2003). Specific Assessment: Progressive Aphasia Language Scale (PALS, 2011)

Problems Regarding Present Definitions Imperfect correlation to

specific pathology (Drachman 2011, Mesulam et al 2014)

Similarities between sub classifications leading to inter-expert & inter-professional disagreement on diagnoses

Strictness re: timing

Changes to diagnoses with timeQuestions surrounding change in diagnosis with

time; initial definitions don’t account for longitudinal observations (Harciarek et al, 2014)

nfvPPA at advanced stages displays:- extrapyramidal features of progressive

supranuclear palsy/corticobasal degeneration, e.g. rigidity, bradykinesia, progressive apraxia

- overlaps with bvFTD (apathy, disorganisation, inattention, poor judgment, inappropirateness, aggression, hyperorality)

- some early executive and WM memory problems

Inconsistent Inter-Rater Reliability?

On reviewing videos of 12 cases, the experts could agree on only 80%, noting that some patients fit none of these patterns (Drachman, 2011).

More sub classifications within a sub classification?

Three variations of logopenic PPA? (Machulda et al 2013)

We need more than just one means of determining a diagnosis

The fact that identical neuropathological entities can cause PPA in some patients while causing bvFTD or amnestic dementias in others justifies the search for susceptibility factors that interact with the neurodegenerative disease to determine its primary anatomical location (Rogalsky et al, 2013).

It also justifies professions working together within and across their specialities to share their knowledge, research & experience to build a larger picture of the different aspects of each variant

Implications for ManagementEvidence to suggest SLT

diagnosis & concurrent treatment can have meaningful outcomes for pt in terms of functional day to day life

Combining language & cognitive ax with multimodal diagnostic criteria, including genetic biomarkers & brain imaging may be the way forward in building knowledge regarding PPA.

Conclusions & Questions