Since the first suggestions of atypical development during the pre-regression period in individuals with RTT, there has been a mounting body of knowledge regarding early functional abnormalities in RTT. This study is a continuation of our previous work reporting on early speech-language dysfunctions in RTT and its preserved speech variant based on retrospective video analysis (Marschik et al., 2009; Marschik, Einspieler, Prechtl, Oberle, & Laccone, 2010; Marschik, Einspieler, et al., 2012; Marschik, Kaufmann, et al., in press; Marschik, Lanator, Freilinger, Prechtl, & Einspieler, 2011; Marschik, Pini, et al., 2012
). It sheds new light on a developmental domain that has been reported to be atypical in RTT, as indicated by retrospective parental questionnaires (Kerr et al., 2006; Lavås et al., 2006; Tams-Little & Holdgrafer, 1996
). We have to keep in mind, however, the limitations of both methods, retrospective questionnaires and retrospective video analysis. The latter has limited value in assessing quantitative aspects of speech-language capacities, as recordings usually do not cover an exhaustive set of acquired capacities (Marschik & Einspieler, 2011
). On the other hand, video analysis allows for direct observation of early speech-language abilities that cannot be reliably assessed using retrospective parent report due to limitations such as potential memory bias and restricted knowledge about communicative and linguistic development (Einspieler et al., 1988; Luyster et al., 2007; Marschik et al., 2007
Using retrospective parental questionnaires, Tams-Little and Holdgrafer (1996)
revealed that gesture use as a precursor for linguistic development was delayed in girls with RTT. Based on this finding – and on reports about delayed gestural development in children with developmental disabilities such as autism spectrum disorder, late talkers, children with specific language impairment, and individuals with acquired brain lesions (Capone & McGregor, 2004; Charman et al., 2003; Hill, Bishop, & Nimmo-Smith, 1998; Sauer, Levine, & Goldin-Meadow, 2010; Thal & Tobias, 1992
) – we expected a delayed onset of the first intentional gesture(s) in girls with RTT. Contrary to our expectations and previous findings, the onset of the first communicative gestures was not delayed in our – admittedly small – sample. The two girls in our study who acquired at least three gestures (Cases 3 and 4) acquired them within one month from the first gesture. On the other hand, early acquisition does not necessarily predict a greater complexity of the gestural repertoire compared to the individuals displaying a later onset of gestures. Case 7, for example, acquired her first gesture at an age of 9 months, but she acquired only one more gesture during the assessment period.
If we have a closer look beyond the appearance of the first gesture(s) and the development of the gestural repertoire, the picture changes dramatically. The overall repertoire of gestures for all individuals was characterized by little variability and a restricted pragmatic functionality. We observed only six different gestures in the entire corpus. This restricted repertoire is in line with previous observations in RTT (Tams-Little & Holdgrafer, 1996
) and also in individuals with autism who were reported to have a limited repertoire of gestures and a lower proportion of gestures combined with vocalizations as compared to typically developing children (Landa, 2008; Wetherby, Yonclas, & Bryan, 1989
). The pragmatic functions covered by the gestural repertoire () are restricted to attention to self, requesting an object, requesting an action and imitation (Sigafoos, Arthur-Kelly, & Butterfield, 2006; Sigafoos, Woodyatt, Keen, et al., 2000
). The repertoire, consisting of demonstrating and passing an object, finger pointing, extending arms toward the caregiver, nodding with the head, and waving bye bye is comparable to the repertoire reported in girls with PSV of RTT (Marschik, Kaufmann, et al., in press
). In addition, as reported earlier (Dahlgren Sandberg, Ehlers, Hagberg, & Gillberg, 2000; Marschik et al., 2009; Marschik, Kaufmann, et al., in press; Tams-Little & Holdgrafer, 1996
), the individual gestural repertoires were very limited with a maximum of six different gestures (range 0–6; ). The limited repertoire of gestures might result from the fact that girls with RTT were reported to have difficulties in focusing their attention to relevant sources of information and exhibit limited behaviors indicative of an intention to communicate (Fabio, Antonietti, Castelli, & Marchetti, 2009; von Tetzchner, 1997; Woodyatt & Ozanne, 1992a, 1992b, 1993
). This is closely related to joint attention behaviors that are considered to play a central role in identifying gestures with communicative intent and in social communication in general (Dahlgren Sandberg et al., 2000; von Tetzchner, 1997
). Indeed, a reduced intention to communicate influences the social-reciprocal system in that children developing atypically tend to be more passive in conversational activities, and that adults in turn are less likely to interact with passive children compared to more active ones (Karmiloff & Karmiloff-Smith, 2001
Classification of the types of observed gestures revealed that four of the six gestures were of deictic character. No gestures were with play scheme character, but there were two symbolic gestures. We agree with Charman et al. (2003)
in describing the gestures as more likely to be instrumental or functional actions rather than symbolic gestures per se. Furthermore, the gestures classified as symbolic gestures here (nodding with the head and waving bye bye) have to be seen in the light of imitations with perseverative character and in close relation to the emergence of stereotypies. Therefore, caution should be taken when making interpretations as some of the observed gestures might mimick communicative behaviors while lacking actual communicative intent. The repertoire of representational gestures might be considered as restricted as Acredolo and Goodwyn (1988)
reported a mean number of three to five representational gestures in infant toddler gestural repertoires.
Another interesting finding was that index finger pointing was only observed in two girls: in Case 4 who had a repertoire of six gestures and also Case 2 who displayed index finger pointing as her only gesture. Again, this finding was comparable to those of girls with PSV of RTT in that these children also had limited pointing abilities (Marschik, Kaufmann, et al., 2012
). This is in line with reports on children with RTT and ASD who overall displayed less pointing, showing objects, and less joint attention as compared to typically developing children (Charman, 1998; Nomura & Segawa, 1990; Shumway & Wetherby, 2009; Stone et al., 1997
Besides the methodological restrictions of video analysis (Marschik & Einspieler, 2011
) one of the limitations of this study is the small sample size that limits generalizability of the findings. Furthermore, the actual range of the gestural repertoire might have been broader than the amount extracted from the video footage. Case 5, for example, is reported here as displaying no gestures, but her footage was the shortest, and some months were not covered sufficiently. Consequently, these findings should be interpreted with caution as this individual may have potentially exhibited gestures that simply were not recorded. Furthermore, retrospective video recordings are not standardized and several factors may vary substantially among recordings, potentially affecting the assessment of communicative behaviors. Variation was often seen in the duration of the recordings, communicative setting (high vs. low communicative settings), number of people involved in the video, etc. (Matson, Wilkins, & González, 2008
). However, video analysis may enable observers to clearly distinguish between potential communicative acts and preintentional communicative forms, i.e. caregivers assigning meaning to the child's behaviors (Sigafoos, Woodyatt, Tucker, Roberts-Pennell, & Pittendreigh, 2000; Woodyatt & Ozanne, 1993
). Another issue to be addressed is the onset of regression in RTT, which is not easily defined and able to be ascribed to a definite date but is rather a gradual process of decline over various developmental domains. Regression in classic RTT as well as in its preserved speech variant is characterized by, at least, the loss of hand skills and productive language (Neul et al., 2010
). Nevertheless, non-verbal communicative functions and motor skills could also be affected. Most commonly, regression takes place between 12 and 18 months, but in a few cases even before 6 months of age or after 36 months (Charman et al., 2002
). The exact onset of regression is, however, difficult to define and might have started in at least some of the individuals of our study by the end of the observation period.
Considering that gestures are a predictor for later language development and scaffold language and cognitive development (Bates et al., 1975; Rowe & Goldin-Meadow, 2009; Tomasello, Striano, & Rochat, 1999
), our findings might contribute to the early detection of RTT. We are cautious not to label it as a contribution to early diagnosis as this requires further study, validation and consideration of other developmental domains. “Early diagnosis is a good development only if the diagnoses are reliable, have good predictive validity, and are useful in assisting better care and prognosis”, as Matson, Wilkins, et al. rightly stated (2008, p. 76)
. Nonetheless, our findings in combination with recent attempts to identify behavioral patterns deviant from typical development may facilitate early detection in the near future.