Speech and lexico-semantic errors during direct cortical stimulation mapping of the language-dominant hemisphere: effects of object and action naming.

OBJECTIVE: In this retrospective study, the authors aimed to establish the stereotactically defined probability distribution for speech (i.e., anarthria, speech arrest) and lexico-semantic errors (i.e., anomia) through direct cortical stimulation (DCS) by using two tasks: action naming and object naming. They also analyzed the patterns of interindividual variability in the localization of the language sites involved, and investigated whether any patient or lesion location factors were associated with greater variability. METHODS: Eighty-one Italian-speaking patients who underwent awake surgery between 2010 and 2021 for low- and high-grade gliomas in eloquent areas of the language-dominant hemisphere were entered in the analyses. The intraoperative DCS protocol included automatic speech tasks, object naming, and action naming. The position of the tags, as depicted on the intraoperative video or photograph, was transposed into Montreal Neurological Institute space. Subsequently, a 2D scatterplot and cluster analysis were performed. Associations between various clinical and radiological characteristics and the quantity of positive stimulated sites were determined by univariate analyses using binary logistic regression. Associated variables (p < 0.2) were included in stepwise multivariate logistic regression with backward elimination (p < 0.05). RESULTS: A total of 1380 cortical sites were stimulated, with a positive response in 511 cases (37%). Most anarthric errors were triggered when stimulating the left precentral gyrus, and most speech arrest errors were elicited when stimulating the left posterior inferior frontal gyrus. Anomias were found in the left inferior frontal gyrus and in the posterior part of the left temporal lobe for object naming. DCS to the left dorsal premotor cortex elicited anomic errors for action naming. Anomias were also elicited during DCS to the left posterior temporal lobe, with both object and action naming. CONCLUSIONS: The distribution of speech and lexico-semantic errors is in line with the current literature. The action-naming results are new and mostly involve the dorsal premotor cortex. These findings stress the importance of maximizing the use of different language tasks during surgery, because even when looking for the same type of errors, different tasks may be better suited to map specific brain regions. DCS with action and object naming identifies more positive sites than object naming alone.

Understanding language and cognition after brain surgery - Tumour grade, fine-grained assessment tools and, most of all, individualized approach.

Cognitive performance influences the quality of life and survival of people with glioma. Thus, a detailed neuropsychological and language evaluation is essential. In this work, we tested if an analysis of errors in naming can indicate semantic and/or phonological impairments in 87 awake brain surgery patients. Secondly, we explored how language and cognition change after brain tumour resection. Finally, we checked if low-tumour grade had a protective effect on cognition. Our results indicated that naming errors can be useful to monitor semantic and phonological processing, as their number correlated with scores on tasks developed by our team for testing these domains. Secondly, we showed that - although an analysis at a whole group level indicates a decline in language functions - significantly more individual patients improve or remain stable when compared to the ones who declined. Finally, we observed that having LGG, when compared with HGG, favours patients' outcome after surgery, most probably due to brain plasticity mechanisms. We provide new evidence of the importance of applying a broader neuropsychological assessment and an analysis of naming errors in patients with glioma. Our approach may potentially ensure better detection of cognitive deficits and contribute to better postoperative outcomes. Our study also shows that an individualized approach in post-surgical follow-ups can reveal reassuring results showing that significantly more patients remain stable or improve and can be a promising avenue for similar reports. Finally, the study captures that plasticity mechanisms may act as protective in LGG versus HGG after surgery.

Language impairments in people with autoimmune neurological diseases: A scoping review.

INTRODUCTION: Autoimmune neurological diseases (ANDs) are a specific type of autoimmune disease that affect cells within the central and peripheral nervous system. ANDs trigger various physical/neuropsychiatric symptoms. However, language impairments in people with ANDs are not well characterized. Here we aimed to determine the kinds of language impairment that most commonly emerge in 10 ANDs, the characteristics of the patients (demographic, neurological damage), and the assessment methods used. METHODS: We followed the PRISMA Extension for Scoping Reviews (PRISMA-ScR). PubMed and Google Scholar were searched. We used a list of search terms containing 10 types of ANDs (e.g., multiple sclerosis, acute disseminated encephalomyelitis) in combination with the terms aphasia, dysphasia, fluency, language, listening, morphology, phonology, pragmatics, reading, semantics, speaking, syntax, writing. The reference lists and citations of the relevant papers were also investigated. The type of AND, patient characteristics, neurological damage and examination technique, language tests administered, and main findings were noted for each study meeting the inclusion criteria. RESULTS: We found 171 studies meeting our inclusion criteria. These comprised group studies and case studies. Language impairments differed largely among types of ANDs. Neurological findings were mentioned in most of the papers, but specific language tests were rarely used. CONCLUSIONS: Language symptoms in people with ANDs are commonly reported. These are often not full descriptions or only focus on specific time points in the course of the disease. Future research needs to assess specific language functions in people with ANDs and relate their language impairments to brain damage at different stages of disease evolution.

What Drives Task Performance in Animal Fluency in Individuals Without Dementia? The SMART-MR Study.

PURPOSE: In this study, we aim to understand whether and how performance in animal fluency (i.e., total correct word count) relates to linguistic levels and/or executive functions by looking at sequence information and item-level metrics (i.e., clusters, switches, and word properties). METHOD: Seven hundred thirty-one Dutch-speaking individuals without dementia from the Second Manifestations of ARTerial disease-Magnetic Resonance study responded to an animal fluency task (120 s). We obtained cluster size and number of switches for the task, and eight different word properties for each correct word produced. We detected variables that determine total word count with random forests, and used conditional inference trees to assess points along the scales of such variables, at which total word count changes significantly. RESULTS: Number of switches, average cluster size, lexical decision response times, word frequency, and concreteness determined total correct word count in animal fluency. People who produced more correct words produced more switches and bigger clusters. People who produced fewer words produced fewer switches and more frequent words. CONCLUSIONS: Concurrent with existing literature, individuals without dementia rely on language and executive functioning to produce words in animal fluency. The novelty of our work is that such results were shown based on a data-driven approach using sequence information and item-level metrics. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.23713269.

Verb and sentence processing with TMS: A systematic review and meta-analysis.

Transcranial magnetic stimulation (TMS) has provided relevant evidence regarding the neural correlates of language. The aim of the present study is to summarize and assess previous findings regarding linguistic levels (i.e., semantic and morpho-syntactic) and brain structures utilized during verb and sentence processing. To do that, we systematically reviewed TMS research on verb and sentence processing in healthy speakers, and meta-analyzed TMS-induced effects according to the region of stimulation and experimental manipulation. Findings from 45 articles show that approximately half of the reviewed work focuses on the embodiment of action verbs. The majority of studies (60%) target only one cortical region in relation to a specific linguistic process. Frontal areas are most frequently stimulated in connection to morphosyntactic processes and action verb semantics, and temporoparietal regions in relation to integration of sentential meaning and thematic role assignment. A meta-analysis of 72 effect sizes of the reviewed papers indicates that TMS has a small overall effect size, but effect sizes for anterior compared to posterior regions do not differ for semantic or morphosyntactic contrasts. Our findings stress the need to increase the number of targeted areas, while using the same linguistic contrasts in order to disentangle the contributions of different cortical regions to distinct linguistic processes.

Lesion-symptom mapping of language impairments in people with brain tumours: The influence of linguistic stimuli.

People with tumours in specific brain sites might face difficulties in tasks with different linguistic material. Previous lesion-symptom mapping studies (VLSM) demonstrated that people with tumours in posterior temporal regions have more severe linguistic impairments. However, to the best of our knowledge, preoperative performance and lesion location on tasks with different linguistic stimuli have not been examined. In the present study, we performed VLSM on 52 people with left gliomas to examine whether tumour distribution differs depending on the tasks of the Aachen Aphasia Test. The VLSM analysis revealed that single-word production (e.g. object naming) was associated with the inferior parietal lobe and that compound and sentence production were additionally associated with posterior temporal gyri. Word repetition was affected in people with tumours in inferior parietal areas, whereas sentence repetition was the only task to be associated with frontal regions. Subcortically, word and sentence production were found to be affected in people with tumours reaching the arcuate fasciculus, and compound production was primarily associated with tumours affecting the inferior longitudinal and inferior fronto-occipital fasciculus. Our work shows that tasks with linguistic stimuli other than single-word naming (e.g. compound and sentence production) relate to additional cortical and subcortical brain areas. At a clinical level, we show that tasks that target the same processes (e.g. repetition) can have different neural correlates depending on the linguistic stimuli used. Also, we highlight the importance of left temporoparietal areas.

The noun-verb distinction.

The comparison between nouns and verbs has been a topic of interest for many researchers over the last 50 years. This comparison, and subsequent behavioral and (partly) anatomic dissociation, has allowed researchers to delve into many topics including the behavioral architecture of the language system and its neural correlates, the underlying nature of the linguistic impairment in individuals with different neurologic disorders, the assessment of language treatment protocols, and the proposal of new protocols aimed to protect the language system of individuals undergoing surgery for brain tumors and epilepsy. Specific to the left temporal lobe, classic accounts have shown its relevance for the processing of nouns and less for the processing of verbs. Nonetheless, more recent accounts indicate that different areas in the left temporal lobe can subserve different functions for the processing of both nouns and verbs. In this chapter, we outlined an overview of key findings of the study of nouns and verbs, with a particular focus on the left temporal lobe. This chapter contextualizes the literature on category-specific impairments and neural correlates of nouns and verbs with linguistic and psycholinguistic theories, and provides new ways to investigate and understand the intricacies of this comparison.

The Aftercare Survey: Assessment and intervention practices after brain tumor surgery in Europe.

Background: People with gliomas need specialized neurosurgical, neuro-oncological, psycho-oncological, and neuropsychological care. The role of language and cognitive recovery and rehabilitation in patients' well-being and resumption of work is crucial, but there are no clear guidelines for the ideal timing and character of assessments and interventions. The goal of the present work was to describe representative (neuro)psychological practices implemented after brain surgery in Europe. Methods: An online survey was addressed to professionals working with individuals after brain surgery. We inquired about the assessments and interventions and the involvement of caregivers. Additionally, we asked about recommendations for an ideal assessment and intervention plan. Results: Thirty-eight European centers completed the survey. Thirty of them offered at least one postsurgical (neuro)psychological assessment, mainly for language and cognition, especially during the early recovery stage and at long term. Twenty-eight of the participating centers offered postsurgical therapies. Patients who stand the highest chances of being included in evaluation and therapy postsurgically are those who underwent awake brain surgery, harbored a low-grade glioma, or showed poor recovery. Nearly half of the respondents offer support programs to caregivers, and all teams recommend them. Treatments differed between those offered to individuals with low-grade glioma vs those with high-grade glioma. The figure of caregiver is not yet fully recognized in the recovery phase. Conclusion: We stress the need for more complete rehabilitation plans, including the emotional and health-related aspects of recovery. In respondents' opinions, assessment and rehabilitation plans should also be individually tailored and goal-directed (eg, professional reinsertion).

Treating lexical retrieval using letter fluency and tDCS in primary progressive aphasia: a single-case study.

Background: In early stages, individuals with Primary Progressive Aphasia (PPA) report language symptoms while scoring within norm in formal language tests. Early intervention is important due to the progressive nature of the disease. Method: We report a single case study of an individual with logopenic variant PPA (lvPPA). We tested whether letter fluency, used as a therapy task, can improve lexical retrieval when combined with tDCS to either the left inferior-frontal gyrus (IFG) or the left inferior parietal lobe (IPL), administered in two separate therapy phases separated by a wash-out period of three months. Outcomes and results: We observed increases in number of words retrieved during a letter fluency task in trained and untrained letters, when letter fluency therapy (LeFT) was administered with anodal tDCS. When LeFT was combined with left IFG stimulation, words produced in a letter fluency task were lower frequency and higher age of acquisition after treatment, compared to before treatment and there was also an increase in accuracy and response times in an untrained picture-naming task. Conclusions: The results indicate that letter fluency therapy combined anodal tDCS is effective in improving lexical retrieval, particularly when left IFG stimulation was used. Effects generalize beyond the trained task, albeit slowing down of responses in picture naming. This task may provide a useful clinical intervention strategy for patients with mild anomia, who are not challenged enough by traditional naming therapies.

What Drives Task Performance in Fluency Tasks in People With HIV?

Introduction: Fluency tasks require language (i.e., semantics, phonological output lexicon, and phonological assembly) and executive functions (i.e., inhibition; mental set shifting; updating, and monitoring). Little is known about whether people with human immunodeficiency virus (HIV) are more impaired on a specific type of fluency task and what aspects of language and executive functions drive such performance. Aims: To understand (1) whether people with HIV are more impaired in animal, letter, or unconstrained fluency relative to a normative sample; (2) whether there exist differences between tasks relative to the total number of words; and (3) which aspects of executive function and language are involved in their performance. Methods: Data from animal, letter, and unconstrained fluency of 50 Spanish-speaking people with HIV were analyzed. The number of switches and mean cluster size for each task and 10 word properties (e.g., frequency, age of acquisition, length in graphemes) for each of the correct words were measured. A chi-square test was used to address Aim 1, linear mixed effects models for Aim 2, and random forests and conditional inference trees for Aim 3. The results were cross-validated with a normative sample. Results: People with HIV were not more impaired in animal, letter, or unconstrained fluency relative to a normative sample. People with HIV produced fewer words in letter fluency compared to animal and unconstrained fluency. In addition, they produced fewer words in animal fluency compared to unconstrained fluency. Number of switches emerged as the most important variable to predict the total number of correct words when considering the three tasks together and for each task separately. Word frequency was relevant to predict animal fluency, age of acquisition to predict letter fluency, and cluster size to predict unconstrained fluency. These results were cross-validated with the exception cluster size. Conclusion: People with HIV rely on language (phonological output lexicon, not necessarily semantics) and executive functioning (updating and monitoring) to produce words in fluency tasks. These results concur with the current literature. Future work may correlate fluency scores with other tests measuring language and executive functions or study other types of fluency tasks (e.g., action, cities, supermarket, and professions).

Mapping Verb Retrieval With nTMS: The Role of Transitivity.

Navigated Transcranial Magnetic Stimulation (nTMS) is used to understand the cortical organization of language in preparation for the surgical removal of a brain tumor. Action naming with finite verbs can be employed for that purpose, providing additional information to object naming. However, little research has focused on the properties of the verbs that are used in action naming tasks, such as their status as transitive (taking an object; e.g., to read) or intransitive (not taking an object; e.g., to wink). Previous neuroimaging data show higher activation for transitive compared to intransitive verbs in posterior perisylvian regions bilaterally. In the present study, we employed nTMS and production of finite verbs to investigate the cortical underpinnings of transitivity. Twenty neurologically healthy native speakers of German participated in the study. They underwent language mapping in both hemispheres with nTMS. The action naming task with finite verbs consisted of transitive (e.g., The man reads the book) and intransitive verbs (e.g., The woman winks) and was controlled for relevant psycholinguistic variables. Errors were classified in four different error categories (i.e., non-linguistic errors, grammatical errors, lexico-semantic errors and, errors at the sound level) and were analyzed quantitatively. We found more nTMS-positive points in the left hemisphere, particularly in the left parietal lobe for the production of transitive compared to intransitive verbs. These positive points most commonly corresponded to lexico-semantic errors. Our findings are in line with previous aphasia and neuroimaging studies, suggesting that a more widespread network is used for the production of verbs with a larger number of arguments (i.e., transitives). The higher number of lexico-semantic errors with transitive compared to intransitive verbs in the left parietal lobe supports previous claims for the role of left posterior areas in the retrieval of argument structure information.

Electrical cortical stimulation can impair production of the alphabet without impairing counting.

Neurosurgery has the potential to cure patients with drug-resistant focal epilepsy, but carries the risk of permanent language impairment when surgery involves the dominant hemisphere of the brain. This risk can be estimated and minimized using electrical stimulation mapping (ESM), which uses cognitive and linguistic tasks during cortical ESM to differentiate "eloquent" and "resectable" areas in the brain. One such task, counting, is often used to screen and characterize language during ESM in patients whose language abilities are limited. Here we report a patient with drug-resistant epilepsy arising from the language-dominant hemisphere using fMRI. Our patient experienced loss of the ability to recite or write the alphabet, but not to count, during ESM of the dominant left posterior superior temporal gyrus. This selective impairment extended to both spoken and written production. We suggest the need for caution when using counting as a sole means to screen language function and as a method of testing low functioning patients using ESM.

Dissociable electrophysiological measures of natural language processing reveal differences in speech comprehension strategy in healthy ageing.

Healthy ageing leads to changes in the brain that impact upon sensory and cognitive processing. It is not fully clear how these changes affect the processing of everyday spoken language. Prediction is thought to play an important role in language comprehension, where information about upcoming words is pre-activated across multiple representational levels. However, evidence from electrophysiology suggests differences in how older and younger adults use context-based predictions, particularly at the level of semantic representation. We investigate these differences during natural speech comprehension by presenting older and younger subjects with continuous, narrative speech while recording their electroencephalogram. We use time-lagged linear regression to test how distinct computational measures of (1) semantic dissimilarity and (2) lexical surprisal are processed in the brains of both groups. Our results reveal dissociable neural correlates of these two measures that suggest differences in how younger and older adults successfully comprehend speech. Specifically, our results suggest that, while younger and older subjects both employ context-based lexical predictions, older subjects are significantly less likely to pre-activate the semantic features relating to upcoming words. Furthermore, across our group of older adults, we show that the weaker the neural signature of this semantic pre-activation mechanism, the lower a subject's semantic verbal fluency score. We interpret these findings as prediction playing a generally reduced role at a semantic level in the brains of older listeners during speech comprehension and that these changes may be part of an overall strategy to successfully comprehend speech with reduced cognitive resources.

Augmented reality for the virtual dissection of white matter pathways.

BACKGROUND: The human white matter pathway network is complex and of critical importance for functionality. Thus, learning and understanding white matter tract anatomy is important for the training of neuroscientists and neurosurgeons. The study aims to test and evaluate a new method for fiber dissection using augmented reality (AR) in a group which is experienced in cadaver white matter dissection courses and in vivo tractography. METHODS: Fifteen neurosurgeons, neurolinguists, and neuroscientists participated in this questionnaire-based study. We presented five cases of patients with left-sided perisylvian gliomas who underwent awake craniotomy. Diffusion tensor imaging fiber tracking (DTI FT) was performed and the language-related networks were visualized separated in different tracts by color. Participants were able to virtually dissect the prepared DTI FTs using a spatial computer and AR goggles. The application was evaluated through a questionnaire with answers from 0 (minimum) to 10 (maximum). RESULTS: Participants rated the overall experience of AR fiber dissection with a median of 8 points (mean ± standard deviation 8.5 ± 1.4). Usefulness for fiber dissection courses and education in general was rated with 8 (8.3 ± 1.4) and 8 (8.1 ± 1.5) points, respectively. Educational value was expected to be high for several target audiences (student: median 9, 8.6 ± 1.4; resident: 9, 8.5 ± 1.8; surgeon: 9, 8.2 ± 2.4; scientist: 8.5, 8.0 ± 2.4). Even clinical application of AR fiber dissection was expected to be of value with a median of 7 points (7.0 ± 2.5). CONCLUSION: The present evaluation of this first application of AR for fiber dissection shows a throughout positive evaluation for educational purposes.

Comparing navigated transcranial magnetic stimulation mapping and "gold standard" direct cortical stimulation mapping in neurosurgery: a systematic review.

The objective of this systematic review is to create an overview of the literature on the comparison of navigated transcranial magnetic stimulation (nTMS) as a mapping tool to the current gold standard, which is (intraoperative) direct cortical stimulation (DCS) mapping. A search in the databases of PubMed, EMBASE, and Web of Science was performed. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and recommendations were used. Thirty-five publications were included in the review, describing a total of 552 patients. All studies concerned either mapping of motor or language function. No comparative data for nTMS and DCS for other neurological functions were found. For motor mapping, the distances between the cortical representation of the different muscle groups identified by nTMS and DCS varied between 2 and 16 mm. Regarding mapping of language function, solely an object naming task was performed in the comparative studies on nTMS and DCS. Sensitivity and specificity ranged from 10 to 100% and 13.3-98%, respectively, when nTMS language mapping was compared with DCS mapping. The positive predictive value (PPV) and negative predictive value (NPV) ranged from 17 to 75% and 57-100% respectively. The available evidence for nTMS as a mapping modality for motor and language function is discussed.

A "Verbal Thermometer" for Assessing Neurodegenerative Disease: Automated Measurement of Pronoun and Verb Ratio from Speech.

Clinicians often use speech to characterize neurodegenerative disorders. Such characterizations require clinical judgment, which is subjective and can require extensive training. Quantitative Production Analysis (QPA) can be used to obtain objective quantifiable assessments of patient functioning. However, such human-based analyses of speech are costly and time consuming. Inexpensive off-the-shelf technologies such as speech recognition and part of speech taggers may avoid these problems. This study evaluates the ability of an automatic speech to text transcription system and a part of speech tagger to assist with measuring pronoun and verb ratios, measures based on QPA. Five participant groups provided spontaneous speech samples. One group consisted of healthy controls, while the remaining groups represented four subtypes of frontotemporal dementia. Findings indicated measurement of pronoun and verb ratio was robust despite errors introduced by automatic transcription and the tagger and despite these off-the-shelf products not having been trained on the language obtained from speech of the included population.

What Drives Task Performance During Animal Fluency in People With Alzheimer's Disease?

BACKGROUND: Animal fluency is a widely used task to assess people with Alzheimer's disease (AD) and other neurological disorders. The mechanisms that drive performance in this task are argued to rely on language and executive functions. However, there is little information regarding what specific aspects of these cognitive processes drive performance on this task. OBJECTIVE: To understand which aspects of language (i.e., semantics, phonological output lexicon, phonological assembly) and executive function (i.e., mental set shifting; information updating and monitoring; inhibition of possible responses) are involved in the performance of animal fluency in people with AD. METHODS: Animal fluency data from 58 people with probable AD from the DementiaBank Pittsburgh Corpus were analyzed. Number of clusters and switches were measured and nine word properties (e.g., frequency, familiarity) for each of the correct words (i.e., each word counting toward the total score, disregarding non-animals and repetitions) were determined. Random forests were used to understand which variables predicted the total number of correct words, and conditional inference trees were used to search for interactions between the variables. Finally, Wilcoxon tests were implemented to cross-validate the results, by comparing the performance of participants with scores below the norm in animal fluency against participants with scores within the norm based on a large normative sample. RESULTS: Switches and age of acquisition emerged as the most important variables to predict total number of correct words in animal fluency in people with AD. Cross-validating the results, people with AD whose animal fluency scores fell below the norm produced fewer switches and words with lower age of acquisition than people with AD with scores in the normal range. CONCLUSION: The results indicate that people with AD rely on executive functioning (information updating and monitoring) and language (phonological output lexicon, not necessarily semantics) to produce words on animal fluency.

Cognitive and language performance predicts effects of spelling intervention and tDCS in Primary Progressive Aphasia.

Predictors of treatment effects allow individual tailoring of treatment characteristics, thereby saving resources and optimizing outcomes. Electrical stimulation coupled with language intervention has shown promising results in improving language performance in individuals with Primary Progressive Aphasia (PPA). The current study aimed to identify language and cognitive variables associated with response to therapy consisting of language intervention combined with transcranial direct current stimulation (tDCS). Forty individuals with PPA received written naming/spelling intervention combined with anodal tDCS or Sham, using a between-subjects, randomized design, with intervention delivered over a period of 3 weeks. Participants were assessed using a battery of neuropsychological tests before and after each phase. We measured letter accuracy during spelling of trained and untrained words, before, immediately after, 2 weeks, and 2 months after therapy. We used step-wise regression methods to identify variables amongst the neuropsychological measures and experimental factors that were significantly associated with therapy outcomes at each time-point. For trained words, improvement was related to pre-therapy scores, in RAVLT (5 trials sum), pseudoword spelling, object naming, digit span backward, spatial span backward and years post symptom onset. Regarding generalization to untrained words, improvement in spelling was associated with pseudoword spelling, RAVLT proactive interference, RAVLT immediate recall. Generalization effects were larger under tDCS compared to Sham at the 2-month post training measurement. We conclude that, for trained words, patients who improve the most are those who retain for longer language skills such as sublexical spelling processes (phoneme-to-grapheme correspondences) and word retrieval, and other cognitive functions such as executive functions and working memory, and those who have a better learning capacity. Generalization to untrained words occurs through improvement in knowledge of phoneme-to-grapheme correspondences. Furthermore, tDCS enhances the generalizability and duration of therapy effects.

The Role of Word Properties in Performance on Fluency Tasks in People with Primary Progressive Aphasia.

People with primary progressive aphasia (PPA) present language difficulties that require lengthy assessments and follow-ups. Despite individual differences, people with PPA are often classified into three variants that present some distinctive language difficulties. We analyzed the data of 6 fluency tasks (i.e., "F", "A", "S", "Fruits", "Animals", "Vegetables"). We used random forests to pinpoint relevant word properties and error types in the classification of the three PPA variants, conditional inference trees to indicate how relevant variables may interact with one another and ANOVAs to cross-validate the results. Results indicate that total word count helps distinguish healthy individuals (N = 10) from people with PPA (N = 29). Furthermore, mean familiarity differentiates people with svPPA (N = 8) from people with lvPPA (N = 10) and nfvPPA (N = 11). No other word property or error type was relevant in the classification. These results relate to previous literature, as familiarity effects have been reported in people with svPPA in naming and spontaneous speech. Also, they strengthen the relevance of using familiarity to identify a specific group of people with PPA. This paper enhances our understanding of what determines word retrieval in people with PPA, complementing and extending data from naming studies.