Bilingualism in Primary Progressive Aphasia: A Retrospective Study on Clinical and Language Characteristics

Psycholinguistic predictors of naming accuracy and decline in bilingual logopenic primary progressive aphasia: a cross-linguistic case study

Naming impairment is a hallmark of logopenic primary progressive aphasia (lvPPA), yet its effects in bilingualism remain understudied. This study examined naming accuracy in a 78-year-old Chinese-English bilingual woman with lvPPA over two years using a modified Boston Naming Test. Naming accuracy was higher in her second, but more frequently used language (English) than her first, but less frequently used language (Chinese). Regression analyses revealed that familiarity predicted naming in Chinese, while word length and age of acquisition influenced English. Decline was linked to age of acquisition in Chinese and emotional properties in English, highlighting language-specific patterns in bilingual lvPPA.

Effects of Cerebellar Transcranial Direct Current Stimulation in Bilingual Logopenic Primary Progressive Aphasia

Background

Primary progressive aphasia (PPA) is a language-based dementia, causing progressive decline of language functions. Transcranial direct current stimulation (tDCS) can augment effects of speech-and language therapy (SLT). However, this has not been investigated in bilingual patients with PPA.

Objective

We evaluated the case of Mr. G., a French (native language, L1)/Dutch (second language, L2)-speaking 59-year-old male, with logopenic PPA, associated with Alzheimer's disease pathology. We aimed to characterize his patterns of language decline and evaluate the effects of tDCS applied to the right posterolateral cerebellum on his language abilities and executive control circuits.

Methods

In a within-subject controlled design, Mr. G received 9 sessions of sham and anodal tDCS combined with semantic and phonological SLT in L2. Changes were evaluated with an oral naming task in L2, the Boston Naming Task and subtests of the Bilingual Aphasia Test in in L2 and L1, the Stroop Test and Attention Network Test, before and after each phase of stimulation (sham/tDCS) and at 2-month follow-up.

Results

After anodal tDCS, but not after sham, results improved significantly on oral naming in L2, with generalization to untrained tasks and cross-language transfer (CLT) to L1: picture naming in both languages, syntactic comprehension and repetition in L2, and response times in the incongruent condition of the Attention Network Test, indicating increased inhibitory control.

Conclusions

Our preliminary results are the first to indicate that tDCS applied to the cerebellum may be a valuable tool to enhance the effects of SLT in bilingual patients with logopenic PPA.

Gaps in clinical research in frontotemporal dementia: A call for diversity and disparities-focused research

Frontotemporal dementia (FTD) is one of the leading causes of dementia before age 65 and often manifests as abnormal behavior (in behavioral variant FTD) or language impairment (in primary progressive aphasia). FTD's exact clinical presentation varies by culture, language, education, social norms, and other socioeconomic factors; current research and clinical practice, however, is mainly based on studies conducted in North America and Western Europe. Changes in diagnostic criteria and procedures as well as new or adapted cognitive tests are likely needed to take into consideration global diversity. This perspective paper by two professional interest areas of the Alzheimer's Association International Society to Advance Alzheimer's Research and Treatment examines how increasing global diversity impacts the clinical presentation, screening, assessment, and diagnosis of FTD and its treatment and care. It subsequently provides recommendations to address immediate needs to advance global FTD research and clinical practice.

Jargonaphasia in logopenic variant primary progressive aphasia

BACKGROUND

Logopenic variant primary progressive aphasia (lvPPA), which is most commonly an early onset variant of Alzheimer's disease (AD), is a progressive impairment in word retrieval and language expression. Clinicians often misdiagnose these patients when they present with severely unintelligible speech consistent with jargonaphasia.

METHODS

We reviewed all patients presenting to a behavioral neurology program over a 23-year period who met criteria for lvPPA after completion of an evaluation extending to positron emission tomography (PET) of the brain. Among these lvPPA patients, we additionally identified and characterized those whose presentation involved incomprehensible yet fluent verbal output.

RESULTS

Out of 95 patients with lvPPA, 9 (9.47%) had jargonaphasia on presentation. These patients differed from the remaining 86 patients in lacking awareness or concern for their impaired communication, having worse mental status scale scores, greater auditory comprehension difficulty, and more bilateral temporo-parietal hypometabolism. In addition, 44.4% of those with jargonaphasia, compared to 14% of those without, were bi/multilingual.

CONCLUSION

Nearly 1 in 10 patients with lvPPA present with severely unintelligible speech. These patients have disease extending to bilateral temporoparietal areas affecting language comprehension and disease awareness. Jargonaphasia can be a confusing presentation of AD and must be differentiated from other progressive aphasias, Wernicke's aphasia, and the word salad of "schizoaphasia".

Bilingual Primary Progressive Aphasia: A Scoping Review of Assessment and Treatment Practices

BACKGROUND

Primary progressive aphasia (PPA) is a neurodegenerative syndrome characterized by speech and/or language impairment with relatively spared cognition. Research investigating behavioral speech-language intervention and methods for cognitive-linguistic assessment in PPA has predominantly centered around monolingual speakers. This gap hinders the widespread adoption of evidence-based approaches and exacerbates the inequities faced by culturally and linguistically diverse populations living with PPA.

OBJECTIVE

This scoping review synthesizes the current evidence for assessment and treatment practices in bilingual PPA as well as the operationalization of bilingualism in PPA.

METHODS

Arksey & O'Malley's scoping review methodology was utilized. Information was extracted from each study and entered into a data-charting template designed to capture information regarding operationalization of bilingualism in PPA and assessment and treatment practices.

RESULTS

Of the 16 identified studies, 14 reported the results of assessments conducted in both languages. Three studies reported positive naming treatment outcomes. Thirteen studies included English-speaking participants, revealing linguistic bias. Most studies reported age of acquisition, proficiency, and patterns of language use rather than providing an operational definition for bilingualism.

CONCLUSIONS

Neither formal assessment measures nor clear guidelines for assessment of bilingual PPA currently exist; however, language-specific measures are emerging. Speech-language intervention in bilingual PPA has been relatively unexplored, representing a significant gap in the literature. In order to improve diagnostic and treatment options for bilingual PPA, targeted efforts to increase representation of bilinguals from various sociocultural contexts, as well as those who speak a variety of language pairs, is necessary.

Can Speaking More Than One Language Help Prevent Alzheimer's Disease?

Alzheimer's disease (AD) is an age-related neurocognitive disorder that is epidemic in the elderly population. Currently, there are limited pharmacological interventions, and this has heightened the urgency to identify potential preventable or modifiable risk factors that promote resilience to the neuropathological effects of AD. The regular use of two or more languages is one such factor that may increases cognitive reserve through the long-standing executive control involved in managing multiple languages in the brain. There is also evidence that bilingualism is associated with increased brain reserve or maintenance, particularly in frontal-executive structures and networks. This review examines the current, sometimes conflicting literature on bi/multilingualism and AD. These studies have confounding variations in the assessment of age of second language onset, language proficiency, language usage, and whether determining incidence of AD or age of symptom onset. Despite these limitations, most publications support the presence of increased frontal-executive reserve that compensates for the development of AD neuropathology and, thereby, delays the emergence of clinical symptoms of dementia by about 4-5 years. Although regularly speaking more than one language does not protect against AD neuropathology, the delay in its clinical expression has a potentially significant impact on the lifelong morbidity from this age-related disease. Learning other languages may be an important modifiable factor for delaying the clinical expression of AD in later life.

Treatment for Anomia in Bilingual Speakers with Progressive Aphasia

Anomia is an early and prominent feature of primary progressive aphasia (PPA) and other neurodegenerative disorders. Research investigating treatment for lexical retrieval impairment in individuals with progressive anomia has focused primarily on monolingual speakers, and treatment in bilingual speakers is relatively unexplored. In this series of single-case experiments, 10 bilingual speakers with progressive anomia received lexical retrieval treatment designed to engage relatively spared cognitive-linguistic abilities and promote word retrieval. Treatment was administered in two phases, with one language targeted per phase. Cross-linguistic cognates (e.g., rose and rosa) were included as treatment targets to investigate their potential to facilitate cross-linguistic transfer. Performance on trained and untrained stimuli was evaluated before, during, and after each phase of treatment, and at 3, 6, and 12 months post-treatment. Participants demonstrated a significant treatment effect in each of their treated languages, with maintenance up to one year post-treatment for the majority of participants. Most participants showed a significant cross-linguistic transfer effect for trained cognates in both the dominant and nondominant language, with fewer than half of participants showing a significant translation effect for noncognates. A gradual diminution of translation and generalization effects was observed during the follow-up period. Findings support the implementation of dual-language intervention approaches for bilingual speakers with progressive anomia, irrespective of language dominance.

Language training for oral and written naming impairment in primary progressive aphasia: a review

BACKGROUND

Primary progressive aphasia (PPA) is a neurodegenerative disorder characterized by a gradual, insidious and progressive loss of language abilities, with naming difficulties being an early and persistent impairment common to all three variants. In the absence of effective pharmacological treatments and given the progressive nature of the disorder, in the past few decades, many studies have investigated the effectiveness of language training to minimize the functional impact of word-finding difficulties in daily life.

MAIN BODY

We review language treatments most commonly used in clinical practice among patients with different variants of PPA, with a focus on the enhancement of spoken and written naming abilities. Generalization of gains to the ability to name untrained stimuli or to other language abilities and the maintenance of these results over time are also discussed. Forty-eight studies were included in this literature review, identifying four main types of language treatment: a) lexical retrieval treatment, b) phonological and/or orthographic treatment, c) semantic treatment, and d) a multimodality approach treatment. Overall, language training is able to induce immediate improvements of naming abilities in all variants of PPA. Moreover, despite the large variability among results, generalization and long-term effects can be recorded after the training. The reviewed studies also suggest that one factor that determines the choice of a particular approach is the compromised components of the lexical/semantic processing system.

CONCLUSION

The majority of studies have demonstrated improvements of naming abilities following language treatments. Given the progressive nature of PPA, it is essential to apply language treatment in the early stages of the disease.

Aphasia in Alzheimer's Disease and Other Dementias (ADOD): Evidence From Chinese

Speech and language impairments (aphasia) are typical of patients with Alzheimer's Disease and other dementias (ADOD) and in some pathologies are diagnostic e.g. Primary Progressive Aphasia (PPA). One question concerns the reliability and validity of symptomatology across typologically different languages. A review of aphasia in ADOD across languages suggests a similar pattern of word comprehension, naming and word finding difficulties but also evidence of language specific features in symptomatology e.g. processing of tone in Chinese languages. Given differences in linguistic impairments across languages, it is recommended that screening for aphasia in community and epidemiological studies use a Short ScreeningTest (SST) that can be delivered across dialects and languages in indigenous languages and also multilingual populations.

Striking loss of second language in bilingual patients with semantic dementia

BACKGROUND

Studies of bilingual or multilingual patients with neurodegenerative diseases that disrupt language like the primary progressive aphasias (PPA) may contribute valuable information on language organization in the bilingual brain and on the factors affecting language decline. There is limited literature on bilingual PPA and in particular on semantic dementia, a type of PPA with selective loss of semantic memory. We studied the nature and severity of naming and comprehension deficits across languages in bilingual patients with semantic dementia (SD).

METHODS

Sixteen bilingual patients with SD and 34 bilingual age-matched controls were administered the modified Boston Naming Test and components of Cambridge Semantic Battery. The patients' performance on picture naming and word comprehension was compared across languages and with controls. The most proficient language on self-rating was labelled as L1 and less proficient as L2.

RESULTS

We observed striking loss of second language (L2) in SD for both receptive and expressive language, even in patients who were premorbidly fluent in their L2. Naming and comprehension in every patient's L2 were impaired relative to both their own first-language (L1) scores and controls' L2 scores. Furthermore, item-specific correct responses in each patient's L2 were a subset of their successes in L1.

DISCUSSION

A striking contrast in performance between two languages in bilingual patients with SD indicates that a bilingual's L2 or less proficient language is more vulnerable to neurodegeneration. Our findings also support a common semantic network in the brain for the different languages of bilinguals.