Les habilitats de comunicació social primerenca i la seua relació amb la competència lingüística i amb la presència de marcadors de risc d’autismeestudi longitudinal dels 8 als 18 mesos d’edat

Resumen

Babies show a natural attraction for human faces since birth (Bedford et al., 2012; Droucker et al., 2013). Likewise, from the first months of life, they show a strong interest in looking at the direction that the adult’s gaze indicates (Farroni et al., 2004). At about 6-8 months old, they learn to deliberately align their own gaze with the adult’s gaze (Beuker et al., 2013). Then, children go from following the direction of the adult's gaze at 6 months old to understanding the intention of this gaze around 12 months of age (Tomasello et al., 2005). With the understanding of the meaning of this gaze, joint attention emerges. Joint attention is the ability to coordinate the attention to adopt a common point of reference with another person. This common point of reference is usually an object or an event of interest (Mundy & Newell, 2007; Salo et al., 2018; Scaife & Bruner, 1975). It is a clear indicator of the comprehension of others’ representations (Brooks & Meltzoff, 2005), and it plays an important role in the emergence of symbolic thinking and language (Jones et al., 2009; Salo et al., 2018). Joint attention has mainly a declaratory functionality, when used to share motivations and interests with others. But it can also have an instrumental-imperative use, when used to achieve an object or an objective (Mundy et al., 2007; Salo et al., 2018). Traditionally, the term joint attention has been used to refer to the declarative use of this communicative behaviour, whereas the term behavioural request is often used to refer to its instrumental-imperative use (Mundy et al., 2003; Seibert et al., 1982). These two dimensions of shared attention are part of what we call "early social communication abilities". In addition to that, we must also include a third dimension: social interaction. Social interaction refers to those behaviours in which the child and the caregiver participate in recreational, of positive affectivity and reciprocity activities (Harrist & Waugh, 2002). It may involve the use of an object, but the reference to the object is not the main feature. Some examples of social interaction are tickling or turn-taking games (Mundy et al., 2003). Joint attention and behavioural request are of a triadic nature, given that typically two interlocutors and an object are involved. On the other hand, social interaction has a dyadic character, because it usually occurs between two people without the need to involve a third element. Thus, we would talk about three dimensions in early social communication: (1) joint attention, (2) behavioural request, and (3) social interaction. Deficits in these abilities, especially difficulties in joint attention, are one of the strongest markers of early signs of autism spectrum disorder (ASD) (Curcio, 1978; Ibáñez et al., 2013; Macari et al., 2012; Mundy et al., 2007; Mundy, 2016; Schertz et al., 2018; Thorup et al., 2018). The objective of this study was to evaluate early social communication in a sample of children born in the province of València, in three evolutionary moments (8, 12 and 18 months). These evaluations were conducted to explore if these early abilities are related to subsequent language skills, and with the presence of ASD early markers at 12 and 18 months of age. This is a prospective longitudinal cohort study with three evaluation moments: 8 months, 12 months and 18 months. The sample was formed of 55 babies born in the province of València and their families: 24 boys (43.6%) and 31 girls (56.4%). At 8 months, 52 children were assessed. At 12 months, 45 children were assessed. At 18 months, 30 children were assessed. Most of these participants at each moment are the same child who was evaluated in all three moments. In some cases, children were evaluated at 8 and 12 months old. In other cases, they were assessed at 8 and 18 months old. A minority of participating children were evaluated only at 8 months old. The recruitment of the sample was carried out with the collaboration of several professionals linked to different Health Centres and Hospitals of the city of València. The instrument used to evaluate early social communication skills was the Early Social-Communication Scales (ESCS) (Mundy et al., 2003). The variables evaluated with this instrument were: lower-level of initiating joint attention (IJAL), higher-level of initiating joint attention (IJAH), responding to proximal joint attention (RJAP), responding to distal joint attention (RJAD), lower-level of initiating behavioural request (IBRL), higher-level of initiating behavioural request (IBRH), responding to behavioural request - total (RBRT), initiating social interaction (ISI), and responding to social interaction - total (RSIT). Lower-level variables refer to communicative behaviours of eye contact and gaze alternation. Higher-level variables refer to gestural communicative behaviours, such as pointing, giving, and showing. When a variable is an initiating variable, that means that it is the child who starts the episode. When a variable is a response variable, that means that the child is responding to an invitation made by the adult. When a variable is proximal, that means that the reference object is at a distance within reach of the child (for example, images in a book). When a variable is distal, that means that the reference object is relatively far (for example, a poster on a wall). Linguistic competence was evaluated with the MacArthur Communicative Development Inventories (MCDI) (Jackson-Maldonado et al., 2003), Spanish adaptation of López Ornat et al. (2005). The linguistic competence variables evaluated at 12 months were: vocalizations (VOC12), word comprehension (WC12), word production (WP12), and gestures and actions (GA12). The linguistic competence variables evaluated at 18 months were: vocalizations (VOC18), word production (WP18), word ending (WEND18), and morphosyntactic complexity (MSYC18). Early markers of ASD symptomatology were evaluated using the First Year Inventory (FYI) (Baranek et al., 2003) at 12 months old, and the Cuestionario de Autismo en la Infancia-Modificado (M-CHAT) (Robins et al., 2001) at 18 months old. At 12 months, the presence of ASD early signs was determined by the score obtained with the FYI. A higher score was indicating a greater presence of early symptomatology. At 18 months, ASD early symptomatology was determined by the presence/absence of early markers, obtained from the application of the M-CHAT (Robins et al., 2001). Data analysis was performed using the statistical analysis program SPSS, version 24.0 (Cor, 2016). Descriptive analyses, correlational analyses, MANOVA, multiple linear regressions and logistic regressions were conducted. The results showed statistically significant correlations between some of the early social communication measures at 8, at 12 and at 18 months. The most noteworthy significant correlations were the following. IJAL and IJAH showed a statistically significant correlation: they correlated positively at 8 months and negatively at 12 months. IJAL and IBRL correlated significantly at 8 months, while their higher-level analogues (IJAH and IBRH) correlated significantly at 12 months. IJAL and RJAP correlated significantly at 8 and 18 months. RJAP and RJAD correlated significantly at 8 and 12 months of age. Finally, ISI and RSIT correlated significantly at 8 months. Regarding the evolution of the early social communication variables, the results indicated that they present different onsets and different growth patterns. IJAL and RJAP are behaviours with an early onset. That is why their growth pattern was flat, with average scores that remained high throughout the three moments. The differences between the moments were not significant for IJAL (8-12 months, 12-18 months and 8-18 months). Regarding RJAP, only the differences between 12 and 18 months were significant. IBRL presented an increase from 8 to 12 months, and a slight decrease from 12 to 18 months. The differences between the moments were significant in all cases for IBRL (8-12 months, 12-18 months and 8-18 months). IJAH, RJAD, IBRD and RBRT presented a generally growing pattern: a zero-average score at 8 months, and an increase between 8 and 12 months and between 12 and 18 months. The differences between the moments were significant in all cases for these variables (8-12 months, 12-18 months and 8-18 months). ISI and RSIT showed a low starting point at 8 months, an increase from 8 to 12 months and a flat pattern from 12 to 18 months. The differences were significant between 8 and 12 months and between 8 and 18 months for ISI and RSIT. Regarding the relationship between early social communication and early ASD signs, the results showed that no measures at 8 months old could significantly predict ASD early symptomatology at 12 months old. However, ASD early markers at 18 months were predicted by IJA and ISI measures at 8 months, and by RJA measures at 12 months. Finally, the results revealed that RJAD measures at 8 months could significantly predict word comprehension at 12 months, while RJAD measures at 12 months could significantly predict vocalization behaviours at 18 months. In summary, it seems that difficulties of joint attention at 8 and 12 months old can be an indicator of the presence of early ASD signs at 18 months. At 8 months, the variables that most informed about this early symptomatology were the initiating joint attention variables. At 12 months, the variables that most informed about this early symptomatology were the responding joint attention variables. With respect to linguistic competence, responding to distal joint attention showed to be one preverbal communication behaviour significantly related to subsequent linguistic competence. It was related to vocabulary at 12 months old, and to vocalization behaviours at 18 months old. This is an investigation that can contribute to a better understanding of the role of early social communication in language development and early detection of ASD. It can be a contribution for future research focused on early detection and intervention. Early intervention is of special interest because, even without confirmation of the diagnosis, it allows the training of social skills with children at risk (Dawson et al., 2010; Johnson, 2008; Kasari et al., 2010, 2012; Reichow & Wolery, 2009; Rogers & Dawson, 2010; Twyman et al., 2009; Zwaigenbaum et al., 2013). In addition to that, it occurs in a stage during childhood development where the brain enjoys greater plasticity, favouring the generation of permanent changes in its physiology (Dawson, 2008; Zwaigenbaum et al., 2013).