Primary deficits of language were reported in 24 of the studies (Azambuja et al, 2012; Caine et al, 1986; Chenery et al, 2002; de Diego-Balaguer et al, 2008; Frank et al, 1996; Garcia et al, 2018; Gordon and Illes, 1987; Hinzen et al, 2018; Hodges et al, 1990; Illes, 1989; Kargieman et al, 2014; Lepron et al, 2009; Murray, 2000; Nemeth et al, 2012; Péran et al, 2004; Saldert et al, 2010; Sambin et al, 2012; Smith et al, 1988; Teichmann et al, 2005, 2006, 2008a, 2008b, 2009; Ullman et al, 1997). For the seven other studies (Hodges et al, 1991; Jensen et al, 2006; Longworth et al, 2005; Murray and Lenz, 2001; Murray and Stout, 1999; Podoll et al, 1988; Wallesch and Fehrenbach, 1988), the authors reported that language deficits in individuals with HD were not primary but were the product of nonlinguistic impairments affecting perceptual, motor, or cognitive functions.
In all of the studies, various instruments were used to assess the participants’ language function. Test batteries included the Boston Diagnostic Aphasia Examination (Goodglass et al, 2001) and the Aachen Aphasia Test (Huber et al, 1984), as well as specific tests such as the Token Test (De Renzi and Faglioni, 1978) and experimental tasks (de Diego-Balaguer et al, 2008; Hinzen et al, 2018; Kargieman et al, 2014; Lepron et al, 2009; Longworth et al, 2005; Nemeth et al, 2012; Péran et al, 2004; Sambin et al, 2012; Smith et al, 1988; Teichmann et al, 2005, 2006, 2008a, 2008b, 2009; Ullman et al, 1997). For this reason, the results of the studies are extremely variable and cannot be easily compared.
As shown in Table 2, we divided the studies into four main categories:
- Studies (n=5) providing an overview of general deficits of language processing in individuals with HD.
- Studies (n=9) specifically targeting production and comprehension impairment in sentence processing, spontaneous speech, and narrative discourse.
- Studies (n=9) on lexical-semantic deficits.
- Studies (n=10) specifically related to impairment in linguistic rule application.
There is some overlap between categories in which studies were grouped according to their main focus. In addition, two studies (Garcia et al, 2018; Jensen et al, 2006) focused on two distinct language domains and are therefore addressed in two categories.
Individuals with HD present with various symptoms, among which chorea is the most characteristic. Motor dysfunction also affects these individuals’ communication abilities in that individuals with HD show dysarthria very early in the course of the disease. With respect to language, a wide variety of impairments were reported in the 31 studies we reviewed.
We grouped the studies into four distinct categories and here discuss general conclusions and controversies about each of the four. We also offer our conclusions on the limitations of the studies and their clinical implications.
Included in the first two categories are studies in which the authors proposed a general description of impaired performance in various language domains and tasks without, however, stating their functional origin, ie, primary or secondary deficits of language. For the studies in the other two categories, the authors explored the impairment of specific linguistic domains in individuals with HD and clearly linked them to functional localizations, ie, lexical-semantic processing and rule application.
Category 1: General Deficit of Language Processing
In five of the reviewed studies (Azambuja et al, 2012; Caine et al, 1986; Chenery et al, 2002; Podoll et al, 1988; Wallesch and Fehrenbach, 1988), the authors provided a general characterization of language impairment in individuals with HD using comprehensive batteries of language assessments, eg, Boston Diagnostic Aphasia Examination and Aachen Aphasia Test. With respect to spoken production, the studies reported deficits of word-finding (all five studies), sentence generation (Chenery et al, 2002), sentence repetition (Azambuja et al, 2012), and narrative discourse and spontaneous speech, ie, loss of initiative and reduction of syntactic complexity (all five studies). As regards written expression, Azambuja et al (2012) reported impairment in narrative writing in 23 participants with HD, whereas Podoll et al (1988) observed the production of dysgraphic errors, mainly characterized by an omission of letters, in the writing to dictation task of the Aachen Aphasia Test battery, in 45 individuals with HD. HD also appeared to affect individuals’ receptive language, with deficits affecting the comprehension of words (Podoll et al, 1988), sentences (Azambuja et al, 2012; Podoll et al, 1988; Wallesch and Fehrenbach, 1988), commands (Azambuja et al, 2012; Chenery et al, 2002; Wallesch and Fehrenbach, 1988), and pragmatics (Chenery et al, 2002). Finally, Podoll et al (1988) reported impairment of visual processing in reading in the middle and later stages of HD, but Azambuja et al (2012) and Caine et al (1986) found reading abilities to be unaffected.
As a whole, the main conclusions of these studies, presented in Table 2, suggest that individuals with HD frequently have deficits affecting all domains of language functioning. However, the extent of these deficits, their functional origin, and their relationship with the disease severity and stage remain unclear.
Category 2: Impairment in Sentence Processing, Spontaneous Speech, and Narrative Discourse
In the present literature review, six studies on language impairment in individuals with HD (Gordon and Illes, 1987; Hinzen et al, 2018; Illes, 1989; Jensen et al, 2006; Murray, 2000; Murray and Lenz, 2001) described participants’ spoken production abilities in spontaneous and narrative speech, and another three studies focused on participants’ spoken production abilities in sentence (Garcia et al, 2018) and discourse (Murray and Stout, 1999; Saldert et al, 2010) comprehension. In four (Gordon and Illes, 1987; Illes, 1989; Murray, 2000; Murray and Lenz, 2001) of the six studies focusing on the production of spontaneous and narrative speech, the authors reported the reduction of syntactic complexity (ie, production of shorter and syntactically simpler sentences) in individuals with HD. However, it is worth noting that the sample sizes of these four studies were quite small, making it difficult to generalize their results (Table 1). In addition to this syntactic impairment, Gordon and Illes (1987), Murray (2000), Murray and Lenz (2001), and Hinzen et al (2018) reported the presence of grammatical errors (eg, absence or inappropriate use of function words, agreement errors, missing or inappropriate referents) in the participants with HD.
Jensen et al (2006), however, suggested that syntactic complexity is preserved in individuals with HD and that the impairment only concerns the grammaticality of sentences. Moreover, according to Jensen et al (2006) and Murray and Lenz (2001), the impairment of narrative speech in individuals with HD is more suggestive of concomitant cognitive and speech deficits than primary language impairment. Using voxel-based morphometry to link specific brain degeneration patterns to narrative speech impairment, Hinzen et al (2018) also showed that, among the participants with HD, there was a significant positive correlation between quantitative measures of language (ie, mean length of utterances and number of words per minute) and the gray matter volume bilaterally in the dorsal basal ganglia. According to Hinzen et al (2018), this finding suggests that the impairment of narrative speech in individuals with HD might be explained in part by underlying alterations of the structures involved in the motor loop and that their linguistic and cognitive origin should be further explored.
In their study on sentence comprehension, Garcia et al (2018) reported that pre-HD and HD participants showed impairment in the syntactic processing of sentences. This impairment was not linked to the overall cognitive profile of the participants, suggesting that frontostriatal degeneration results in a grammatical impairment, even in the presymptomatic stage of the disease. The two studies (Murray and Stout, 1999; Saldert et al, 2010) examining discourse comprehension also reported difficulties in individuals with HD. In the Stout study (1999), nine participants with HD listened to short stories and responded to questions with yes/no answers. Compared to healthy controls, participants with HD showed specific difficulty answering questions about stated and implied details. Those authors also found positive correlations between discourse comprehension performances and dementia severity ratings as well as between discourse comprehension and measures of memory and attention. According to them, and in contrast to Garcia et al (2018), the comprehension impairment in individuals with HD might, therefore, reflect cognitive deficits. In 2010, Saldert et al also showed that participants with HD, even in the early stages of the disease, have difficulties in discourse comprehension for both explicit and ambiguous information. They found that these individuals also encounter difficulties in the comprehension of metaphors and lexical ambiguities in sentences, a deficit previously reported by Chenery et al (2002). According to Saldert et al (2010), such difficulties may result in a pragmatic impairment that might cause problems in individuals’ conversational interactions.
In summary, studies involved in the present review reported impairment for people with HD at the sentence and the discourse level in both the production and comprehension linguistic domains. In production, this impairment affects the syntactic complexity and/or grammatical form of sentences; in comprehension, difficulties are encountered for explicit and implicit information. As for the studies reported in the section on general deficit of language processing, the authors did not specify the functional origin of these difficulties and impairment. Moreover, the conclusions of some of these studies should be considered with caution considering their very small sample size, especially those studies exploring production deficits.
Category 3: Lexical-Semantic Deficits
Nine studies in the present review specifically explored the functional origin of lexical-semantic deficits in individuals with HD.
In five of them (Frank et al, 1996; Garcia et al, 2018; Hodges et al, 1990; Kargieman et al, 2014; Smith et al, 1988), the authors specifically explored individuals’ semantic processing abilities. In one study conducted with 14 participants with HD, Hodges et al (1990) concluded that the participants’ semantic knowledge was relatively preserved. However, in the other four studies (Frank et al, 1996; Garcia et al, 2018; Kargieman et al, 2014; Smith et al, 1988), access to the semantic knowledge of objects was shown to be disrupted in individuals with HD. It must be noted that the studies of Frank et al (1996) and Smith et al (1988) were conducted with participants with mild and moderate dementia associated with HD. This may explain the presence of semantic impairment due to disease progression. Garcia et al (2018) and Kargieman et al (2014), however, found that participants with HD without dementia showed semantic impairment for both object and action concepts, whereas pre-HD participants were affected for action concepts only. According to these authors, such results suggest that frontostriatal degeneration leads to an action-semantic impairment that might constitute an early marker of HD. Moreover, Garcia et al (2018) suggested that the impairment for object knowledge may reflect the widespread atrophy in temporal and parietal regions observed in individuals with HD as the disease progresses.
In two of the nine studies on lexical-semantic deficits in HD, difficulties in retrieving lexical forms of concepts were reported in narrative and spontaneous speech (Gordon and Illes, 1987; Illes, 1989), whereas Jensen et al (2006) found that participants with HD did not display more word-finding difficulties than controls in a picture description task.
Lexical access was also specifically explored in six studies through word generation (Lepron et al, 2009; Péran et al, 2004) and picture naming (Frank et al, 1996; Hodges et al, 1990, 1991; Smith et al, 1988) tasks. Inconsistent results were reported for verb generation tasks. Péran et al (2004) showed that, as a whole, the performance of the participants with HD was impaired in noun and verb generation tasks; a specific deficit for verb production was found only in participants with HD with dementia. According to the authors, this verb production deficit could be explained by the impairment of the semantic representation of actions in HD, resulting from the pathology affecting the basal ganglia circuitry at later stages of the disease. Also using a word generation task, Lepron et al (2009) reported difficulties in 12 HD participants without dementia in terms of reaction time and proportion of errors, without a difference between nouns and verbs.
Positron emission tomography data also revealed that the brain regions (the anterior cingulate and inferior frontal gyri) usually involved in lexical retrieval were not activated in the participants with HD, but activation was found in those regions involved in the phonological loop (left supramarginal gyrus) and effortful retrieval (right inferior frontal gyrus), suggesting that they compensate for word selection processes.
It is worth noting that Jensen et al (2006) also found that, compared to the control group, participants with HD (n = 6) produced fewer verbs in a picture description task.
Finally, impairment on the Boston Naming Test (BNT) (Kaplan et al, 1983) was found in four studies in this category. However, picture naming tests such as the BNT include various processing steps involving visual perception and recognition, activation of semantic representations, and lexical retrieval, which makes it difficult to identify the functional locus of impairment. In two of the studies (Frank et al, 1996; Smith et al, 1988), the authors reported impairment on the BNT in HD participants with mild and moderate dementia. They attributed this impairment to a breakdown in the organization of lexical-semantic representations (Smith et al, 1988) or to semantic access disruption (Frank et al, 1996). In their 2-year longitudinal study, Hodges et al (1990) also reported impairment on the BNT by participants with HD. However, the authors concluded that, because the participants’ performance on tasks exploring semantic memory remained stable over time, their semantic knowledge was unimpaired and was not at the origin of their naming deficit. The performance of the participants with HD on the BNT was also impaired in the Hodges et al (1991) study. There the participants with HD produced significantly more visual-based errors than did the healthy participants. The authors interpreted this result as reflecting a disruption of perceptual analysis rather than a semantic impairment.
In summary, except for Hodges et al (1990, 1991), the studies reviewed here suggest that the semantic processing abilities of object and action concepts are impaired in individuals with HD, including the presymptomatic stage of the disease. As a whole, these studies also show impairment of lexical access to concrete nouns in individuals with HD, although the results remain inconsistent for verbs.
Category 4: Impairment in Linguistic Rule Application
According to the declarative/procedural model proposed by Ullman (2001) and Ullman et al (1997), declarative memory is sustained by medial temporal lobe structures and underlies the mental lexicon in which the phonological forms of words are stored. Procedural memory, rooted in the frontostriatal circuits of the brain, sustains the acquisition and computation of rule-based linguistic procedures. Support for this model comes from studies conducted with individuals suffering from poststroke aphasia (Ullman et al, 2005), Parkinson disease (Ullman et al, 1997), and Alzheimer disease (Walenski et al, 2009). In 10 studies included in the present review, HD was used as a clinical model to test the assumptions of the declarative/procedural model (Ullman, 2001).
In the only study on the perception of phonemes and the application of phonological rules in words and sentences, Teichmann et al (2009) found reduced abilities of phoneme discrimination in sentences in the 15 participants with HD. The authors concluded that the striatum does not play a role in phonological rule application but rather underlies phonological short-term memory capacities engaged in sentence listening.
In 2008, de Diego-Balaguer and colleagues assessed the ability to extract lexical rules in 13 pre-HD and 43 HD participants using a simplified artificial language. The performance of the pre-HD participants was unimpaired, but the participants with HD showed significant impairment in word-rule learning. According to the authors, these results suggest that striatal degeneration in individuals with HD impairs the earliest stages of language learning when no semantic information is available. Moreover, this impairment was significantly correlated with neuropsychological measures of working memory and attentional control, suggesting their involvement in language acquisition.
In the morphological domain, five studies showed that individuals with HD have difficulty applying infrequent morphological rules, leading to errors in verb conjugation (Nemeth et al, 2012; Teichmann et al, 2005, 2008b; Ullman et al, 1997) and acceptability judgment on conjugated verbs (Teichmann et al, 2006). The authors attributed this impairment to striatal damage that may reduce inhibition of the most frequent linguistic rules, thereby leading to the production of overregularization errors. In these five studies, the conjugation of irregular verbs, which is retrieved from lexical memory, was less impaired than the conjugation of regular verbs, which is rule-governed. This dissociation was interpreted as support for the declarative/procedural model. In contrast, Longworth et al (2005) did not find any differences between regular and irregular verbs in past tense production and comprehension tasks in a study conducted with 10 individuals with HD. These patients had difficulties suppressing semantically appropriate alternatives when trying to conjugate novel verbs. This result led the authors to conclude that the striatum does not have an essential role in morphological rule application, but rather plays a restricted, non-language-specific, inhibitory role in language processing.
Finally, the syntactic abilities of individuals with HD were explored in four of the studies we reviewed (Sambin et al, 2012; Teichmann et al, 2005, 2008a, 2008b). The authors of these four studies found that participants with HD had difficulties applying syntactic rules, suggesting that the striatum is involved in syntactic rule processing.
In summary, according to 8 of the 31 studies reviewed in this article, individuals with HD present with difficulties in word-rule extraction and morphological and syntactic rule application resulting from striatal damage. However, involvement of the striatum in morphological rule application was challenged in the Longworth et al (2005) study.
HD has detrimental effects on an individual’s speech, mainly due to dysarthria. Based on the studies reported in this literature review, one can also conclude that language is impaired in individuals with HD, whatever the disease stage.
Results from the studies presenting a general overview of language suggested that individuals diagnosed with HD frequently have deficits affecting all domains of language functioning. Other studies focusing on specific language domains showed that individuals with HD may have difficulties producing and understanding sentences and discourse, processing semantic representations of object and action concepts, retrieving lexical forms of concrete nouns, and extracting and applying linguistic rules. Moreover, deficits affecting the production of narrative discourse (Hinzen et al, 2018), sentence comprehension (Garcia et al, 2018), semantic processing of action concepts (Garcia et al, 2018), and verb conjugation (Nemeth et al, 2012) have been reported in individuals at the presymptomatic stage of the disease. At the other end of the disease continuum, a worsening of language impairment was found in participants with dementia associated with HD in tasks exploring lexical access to nouns and verbs (Frank et al, 1996; Péran et al, 2004; Smith et al, 1988) and discourse comprehension (Murray and Stout, 1999). Figure 2 is a graphic summary of the main results of our literature review.
The studies revealed some inconsistencies in findings related to reading abilities, syntactic complexity in sentence production, semantic processing, and application of morphological rules in verb conjugation. A possible explanation may lie in the heterogeneity of the studies with respect to clinical samples (eg, diagnostic process, size) and methods used. As a whole, the research samples in the studies were small, and participants were at different stages of the disease. In HD, the neurodegeneration extends mainly from the striatum to a wide cortical degeneration, so the deficits in one domain of language may precede others over the course of the disease, thus explaining some of the seeming discrepancies between studies. Various standardized tests were used to measure language abilities. In addition, experimental tasks were used in a few of the studies to measure very specific aspects of language and to test theoretical models of language processing. Therefore, further studies conducted within a cognitive framework of assessment are needed to identify the functional origin of language disturbances in individuals with HD. These studies should focus particularly on discourse organization and planning, pragmatics, written production, and reading abilities, for which the picture remains unclear.
Considering the important contribution of the frontostriatal regions to cognitive processes such as executive functions and working memory (Hedden and Gabrieli, 2010; Landau et al, 2009), it is notable that only a few of the studies in our review explored the primary nature of language impairment in individuals with HD. Further studies are needed to disentangle specific language impairment in individuals with HD from those resulting from general cognitive disruptions.
Finally, clinical studies are also needed to determine the impact of language impairment in individuals with HD on functional communication in daily living, as well as to chart their progression over the course of the disease.
Albert MLKatzman R, Terry RD, Bick KL. 1978. Subcortical dementia. Alzheimer’s Disease: Senile Dementia and Related Disorders. New York, New York: Raven Press; 7:173–180.
Azambuja MJ, Radanovic M, Haddad MS, et al. 2012. Language impairment
in Huntington’s disease. Arq Neuropsiquiatr. 70:410–415.
Bak TH, Hodges JR. 2003. Kissing and dancing: a test to distinguish the lexical and conceptual contributions to noun/verb and action/object dissociation. J Neuroling. 16:169–181.
Bayles KA. 1982. Language function in senile dementia. Brain Lang. 16:265–280.
Brookshire RH, Nicholas LE. 1993. The Discourse Comprehension Test. Tucson, Arizona: Communication Skill Builders.
Caine ED, Bamford KA, Schiffer RB, et al. 1986. A controlled neuropsychological comparison of Huntington’s disease and multiple sclerosis. Arch Neurol. 43:249–254.
Chenery HJ, Copland DA, Murdoch BE. 2002. Complex language functions and subcortical mechanisms: evidence from Huntington’s disease and patients with non-thalamic subcortical lesions. Int J Lang Commun Disord. 37:459–474.
Crosson B. 1985. Subcortical functions in language: a working model. Brain Lang. 25:257–292.
Crosson B, Benefield H, Cato MA, et al. 2003. Left and right basal ganglia and frontal activity during language generation: contributions to lexical, semantic, and phonological processes. J Int Neuropsychol Soc. 9:1061–1077.
Damasio AR, Damasio H, Rizzo M, et al. 1982. Aphasia with nonhemorrhagic lesions in the basal ganglia and internal capsule. Arch Neurol. 39:15–24.
de Diego-Balaguer R, Couette M, Dolbeau G, et al. 2008. Striatal degeneration impairs language learning: evidence from Huntington’s disease. Brain. 131 (Pt 11):2870–2881.
De Renzi E, Faglioni P. 1978. Normative data and screening power of a shortened version of the Token Test. Cortex. 14:41–69.
Frank EM, McDade HL, Scott WK. 1996. Naming in dementia secondary to Parkinson’s, Huntington’s, and Alzheimer’s diseases. J Commun Disord. 29:183–197.
Friederici AD, Kotz SA. 2003. The brain basis of syntactic processes: functional imaging and lesion studies. Neuroimage. 20(suppl 1):S8–S17.
Garcia AM, Bocanegra Y, Herrera E, et al. 2018. Action-semantic and syntactic deficits in subjects at risk for Huntington’s disease. J Neuropsychol. 12:389–408.
Goodglass H, Kaplan E, Barresi BA. 2001. Boston Diagnostic Aphasia Examination. Philadelphia, Pennsylvania: Lippincott Williams & Wilkins.
Gordon WP, Illes J. 1987. Neurolinguistic characteristics of language production in Huntington’s disease: a preliminary report. Brain Lang. 31:1–10.
Hedden T, Gabrieli JD. 2010. Shared and selective neural correlates of inhibition, facilitation, and shifting processes during executive control. Neuroimage. 51:421–431.
Helm-Estabrooks N. 1992. Aphasia Diagnostic Profiles. Chicago, Illinois: Riverside.
Hinzen W, Rossello J, Morey C, et al. 2018. A systematic linguistic profile of spontaneous narrative speech in pre-symptomatic and early stage Huntington’s disease. Cortex. 100:71–83.
Hodges JR, Salmon DP, Butters N. 1990. Differential impairment of semantic and episodic memory in Alzheimer’s and Huntington’s diseases: a controlled prospective study. J Neurol Neurosurg Psychiatry. 53:1089–1095.
Hodges JR, Salmon DP, Butters N. 1991. The nature of the naming deficit in Alzheimer’s and Huntington’s disease. Brain. 114 (Pt 4):1547–1558.
Howard D, Patterson K. 1992. The Pyramids and Palm Trees Test: A Test for Semantic Access From Words and Pictures. Bury St Edmunds, UK: Thames Valley Test Company.
Huber W, Poeck K, Willmes K. 1984. The Aachen Aphasia Test. Adv Neurol. 42:291–303.
Huisingh R, Barrett M, Zachman L. 1990. The Word Test-Revised. Moline, Illinois: LinguiSystems.
Huntington Study Group. 1996. Unified Huntington’s Disease Rating Scale: reliability and consistency. Mov Disord. 11:136–142.
Illes J. 1989. Neurolinguistic features of spontaneous language production dissociate three forms of neurodegenerative disease: Alzheimer’s, Huntington’s, and Parkinson’s. Brain Lang. 37:628–642.
Jensen AM, Chenery HJ, Copland DA. 2006. A comparison of picture description abilities in individuals with vascular subcortical lesions and Huntington’s disease. J Commun Disord. 39:62–77.
Kaplan E, Goodglass H, Weintraub S. 1983. The Boston Naming Test. Philadelphia, Pennsylvania: Lea & Febiger.
Kargieman L, Herrera E, Baez S, et al. 2014. Motor-language coupling in Huntington’s disease families. Front Aging Neurosci. 6:122.
Kertesz A. 1982. The Western Aphasia Battery. New York, New York: Grune & Stratton.
Landau SM, Lal R, O’Neil JP, et al. 2009. Striatal dopamine and working memory. Cereb Cortex. 19:445–454.
Lepron E, Péran P, Cardebat D, et al. 2009. A PET study of word generation in Huntington’s disease: effects of lexical competition and verb/noun category. Brain Lang. 110:49–60.
Liberati A, Altman DG, Tetzlaff J, et al. 2009. The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: explanation and elaboration. Ann Intern Med. 151:W65–W94.
Longworth CE, Keenan SE, Barker RA, et al. 2005. The basal ganglia and rule-governed language use: evidence from vascular and degenerative conditions. Brain. 128:584–596.
Marangolo P, Piras F. 2008. Dissociations in processing derivational morphology: the right basal ganglia involvement. Neuropsychologia. 46:196–205.
Mattis S. 1988. Dementia Rating Scale. Odessa, Florida: Psychological Assessment
McColgan P, Tabrizi SJ. 2018. Huntington’s disease: a clinical review. Eur J Neurol. 25:24–34.
Murray LL. 2000. Spoken language production in Huntington’s and Parkinson’s diseases. J Speech Lang Hear Res. 43:1350–1366.
Murray LL, Lenz LP. 2001. Productive syntax abilities in Huntington’s and Parkinson’s diseases. Brain Cogn. 46:213–219.
Murray LL, Stout JC. 1999. Discourse comprehension in Huntington’s and Parkinson’s diseases. Am J Speech Lang Pathol. 8:137–148.
Nemeth D, Dye CD, Sefcsik T, et al. 2012. Language deficits in pre-symptomatic Huntington’s disease: evidence from Hungarian. Brain Lang. 121:248–253.
Paoli RA, Botturi A, Ciammola A, et al. 2017. Neuropsychiatric burden in Huntington’s disease. Brain Sci. 7:67.
Paulsen JS, Langbehn DR, Stout JC, et al. 2008. Detection of Huntington’s disease decades before diagnosis: the Predict-HD study. J Neurol Neurosurg Psychiatry. 79:874–880.
Péran P, Demonet JF, Pernet C, et al. 2004. Verb and noun generation tasks in Huntington’s disease. Mov Disord. 19:565–571.
Podoll K, Caspary P, Lange HW, et al. 1988. Language functions in Huntington’s disease. Brain. 111 (Pt 6):1475–1503.
Reisberg B, Ferris SH, DeLeon MH, et al. 1982. The global deterioration scale for assessment
of primary degenerative dementia. Am J Psychiatry. 139:1136–1139.
Rub U, Seidel K, Heinsen H, et al. 2016. Huntington’s disease (HD): the neuropathology of a multisystem neurodegenerative disorder of the human brain. Brain Pathol. 26:726–740.
Saldert C, Fors A, Stroberg S, et al. 2010. Comprehension of complex discourse in different stages of Huntington’s disease. Int J Lang Commun Disord. 45:656–669.
Sambin S, Teichmann M, de Diego Balaguer R, et al. 2012. The role of the striatum in sentence processing: disentangling syntax from working memory in Huntington’s disease. Neuropsychologia. 50:2625–2635.
Shoulson I. 1981. Huntington disease
: functional capacities in patients treated with neuroleptic and antidepressant drugs. Neurol. 31:1333–1335.
Shoulson I, Fahn S. 1979. Huntington’s disease: clinical care and evaluation. Neurol. 29:1–3.
Schulte J, Littleton JT. 2011. The biological function of the Huntingtin protein and its relevance to Huntington’s Disease pathology. Curr Trends Neurol. 5:65–78.
Smith S, Butters N, White R, et al. 1988. Priming semantic relations in patients with Huntington’s disease. Brain Lang. 33:27–40.
Sturrock A, Leavitt BR. 2010. The clinical and genetic features of Huntington disease
. J Geriatr Psychiatry Neurol. 23:243–259.
Teichmann M, Darcy I, Bachoud-Lévi AC, et al. 2009. The role of the striatum in phonological processing: evidence from early stages of Huntington’s disease. Cortex. 45:839–849.
Teichmann M, Dupoux E, Cesaro P, et al. 2008a. The role of the striatum in sentence processing: evidence from a priming study in early stages of Huntington’s disease. Neuropsychologia. 46:174–185.
Teichmann M, Dupoux E, Kouider S, et al. 2005. The role of the striatum in rule application: the model of Huntington’s disease at early stage. Brain. 128:1155–1167.
Teichmann M, Dupoux E, Kouider S, et al. 2006. The role of the striatum in processing language rules: evidence from word perception in Huntington’s disease. J Cogn Neurosci. 18:1555–1569.
Teichmann M, Gaura V, Demonet JF, et al. 2008b. Language processing within the striatum: evidence from a PET correlation study in Huntington’s disease. Brain. 131:1046–1056.
Tettamanti M, Moro A, Messa C, et al. 2005. Basal ganglia and language: phonology modulates dopaminergic release. Neuroreport. 16:397–401.
Ullman MT. 2001. A neurocognitive perspective on language: the declarative/procedural model. Nature Rev Neurosci. 2:717–726.
Ullman MT, Corkin S, Coppola M, et al. 1997. A neural dissociation within language: evidence that the mental dictionary is part of declarative memory, and that grammatical rules are processed by the procedural system. J Cogn Neurosci. 9:266–276.
Ullman MT, Pancheva R, Love T, et al. 2005. Neural correlates of lexicon and grammar: evidence from the production, reading, and judgment of inflection in aphasia. Brain Lang. 93:185–238.
Vannest J, Polk TA, Lewis RL. 2005. Dual-route processing of complex words: new fMRI evidence from derivational suffixation. Cogn Affect Behav Neurosci. 5:67–76.
Vonsattel JP, Myers RH, Stevens TJ, et al. 1985. Neuropathological classification of Huntington’s disease. J Neuropathol Exp Neurol. 44:559–577.
Walenski M, Sosta K, Cappa S, et al. 2009. Deficits on irregular verbal morphology in Italian-speaking Alzheimer’s disease patients. Neuropsychologia. 47:1245–1255.
Wallesch CW, Fehrenbach RA. 1988. On the neurolinguistic nature of language abnormalities in Huntington’s disease. J Neurol Neurosurg Psychiatry. 51:367–373.
Wechsler D. 1981. Wechsler Adult Intelligence Scale Revised. New York, New York: Harcourt Brace Jovanovich.
Wiig EH, Secord W. 1989. Test of Language Competence-Expanded. New York, New York: Psychological Corporation.
Wiig EH, Secord W. 1992. Test of Word Knowledge. San Antonio, Texas: Psychological Corporation.
Keywords:Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved
Huntington disease; language impairment; assessment