As summarized in the first part of the present chapter, dementia of the Alzheimer’s type is a neurodegenerative disease, which affects millions of elderlies. It is determined by major changes in the brain, which consist of neural loss, neurofibrillary tangles and plaques (Braak & Del Tredici; 2006; Hyam, 2006).
A variety of symptoms characterizes the disease: memory loss, apraxia, agnosia, anomia, behavioural disorders and psychiatric disorders are the most common ones (Spinnler, 1996). Usually, patients do not experience all of them at the same time.
Different symptoms can appear in different stages of the disease and their incidence can vary. However, the overall impairment progressively worsens to the point that PADs lose their autonomy in everyday life.
As for the linguistic impairment, the main deficit is anomia. Most authors now agree in ascribing it to a gradual loss of semantic knowledge, in association with retrieval difficulties (Chertkow & Bub 1990; Cuetos et al., 2015). The hypothesis of a disruption of semantic knowledge as the main cause to anomia has been supported by three kinds of evidence. First, item-by-item analyses show that PADs tend to perform consistently on single words across tasks: either they perform always correctly or they perform always wrong on the same word in different tests (Chertkow et al., 1989; Chertkow & Bub, 1990).
Second, their ability to name objects correlates with the amount and the quality of information that they retain about the objects (Hodges et al., 1996; Ralph et al., 1997).
Third, the analysis of errors in naming tasks reveals a progressive pattern of disruption at the semantic level: the main error type shifts from with-in category errors, to superordinate labels and finally to nonresponses (Almor et al., 2009; Hodges et al., 1991).
In this process of lexical disruption, frequency (Cuetos et al., 2005, 2015; Forbes-MacKay et al., 2005; Tippett et al., 2007), age of acquisition (Cuetos et al., 2005, 2012; Silveri et al., 2002), and grammatical category (Almor et al., 2009; Grossman et al., 1996; among others) seem to be good predictors for the words that keep spared longer. PADs perform
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better with high-frequency and early-acquired words; and verbs are more impaired than nouns.
With respect to verb retrieval and use in PADs, Kim & Thompson (2003) observe that PADs perform equally on verbs characterized by different numbers of arguments.
Moreover, Grossman et al. (2007) notice that PADs can acquire syntactic information about new words but not their meaning. Taken together, the two studies suggest that there might be a dissociation between the syntactic and the semantic information in the lexicon of PADs. The idea is very appealing; however, the collected data are poor (and not very consistent), and robust conclusions cannot be met. For this reason, further research on the issue is needed.
Lexical disruption also affects irregular verbal morphology, while regular morphology is usually spared. This supports the hypothesis put forth by Ullman (2001) of a dissociation between declarative knowledge and procedural mechanism: the former is impaired, while the latter is relatively spared in PADs (Colombo et al., 2009; Walenski et al., 2009).
The last part of the chapter contains an overview of studies on sentence comprehension. So far, two factors have been taken into account for impaired comprehension: impaired Working Memory (Baddeley et al., 1991; Kempler et al., 1998;
Small et al., 2000) and the effects of non-canonical assignments of theta-roles (Grossman
& White-Devine, 1998; Manouilidou et al., 2009). Some studies also point out an impaired comprehension of relative clauses, with respect to main clauses (Bickel et al., 2000; Kempler et al., 1998; Small et al., 2000; Waters et al., 1998).
Unfortunately, the tasks in use contained some confounding factors and did not allow for more subtle observations. For this reasons, as pointed out at the end of section 2.5.4, more investigation is needed with respect to the syntactic deficit of PADs.
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3 GRAMMATICAL GENDER RETRIEVAL
3.0 Introduction
It is generally agreed upon that grammatical gender (GG) is a linguistic phenomenon that plays a major role at the lexical level and at the syntactic one (Cacciari and Cubelli, 2003;
Caramazza and Miozzo, 1997; Carstens, 2000; Friedmann and Biran, 2003; a.m.o.):
information on GG is independently stored in the lexicon20, attached to the lexical item, and is required for syntactic agreement.
GG retrieval is described as a phenomenon that can be classified under either the declarative or the procedural components of linguistic faculty, depending on how, and for which purpose, the lexicon is accessed (Goodglass, 2000). For example, speakers show procedural knowledge of GG whenever they automatically and accurately use gender agreement in a phrase; in contrast, declarative knowledge is retained in conscious metalinguistic judgement on gender class. Under a different perspective, grammatical gender is procedurally retrieved whenever this can be inferred from the word form; while in case this is not possible, speakers must resort to their declarative knowledge about grammatical gender (see below in this chapter). Previous research on the linguistic competence of PADs has shown hints of a possible dissociation between procedural and declarative components, with a better preservation of the former in comparison to the latter, much more likely to undergo erosion (cf. Colombo et al. (2009), and Walenski et al. (2009) on the asymmetry between regular and irregular verbal morphology). For the present research on PADs, GG is then particularly interesting in consideration of its transversal function and relevance. If the hypothesis of a dissociation in PADs between procedural and declarative knowledge is correct, as well as the premises on grammatical gender are, I expect to find a clear pattern of performance in PADs, with a good performance whenever they can rely on procedural retrieval, in comparison to cases in which declarative knowledge about GG is required.
20 Exceptions to this analysis will be discussed in what follows.
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To the writer’s knowledge, the number of studies that have questioned the status of grammatical gender in Italian-speaking PADs is very narrow (Manenti et al., 2004;
Paganelli et al., 2003). I will discuss thoroughly the results of those studies in the next sections; for the moment it is sufficient to mention that in one study, PADs have a certain sensitivity to GG (Manenti et al., 2004), both in the form of facilitation and of interference in a semantic and gender priming task. In the other study, PADs fail at providing proof of gender retention in semantic errors (Paganelli et al., 2003), thus suggesting an impairment at the level of GG activation in the process of lexical retrieval.
The present chapter is organized as follow: in 3.1 I present some relevant information on grammatical gender with the purpose of highlighting how this morphosyntactic phenomenon can bare different characteristics across languages. As a consequence of this first observation, I would like to remark that any conclusions reached in the present work about GG only concern the Italian linguistic system and therefore should not be extended to other languages. In 3.2 I illustrates the Italian GG system in order to make the reader familiar with it. Section 3.3 deals with the role of GG at the syntactic level. The process of GG retrieval is illustrated in 3.4. In 3.5 I review experimental studies that unveiled the vulnerability of GG in bilingual as well as in aphasic speakers. Finally, previous studies on the status of GG in PADs are summarized in 3.6. In 3.7 I recap the relevant information for the reasons behind the experimental task I present in Chapter 4.