How facial expressions in a Rett syndrome population are recognised and interpreted by those around them as conveying emotions Ma ¨ rith Bergstro ¨ m-Isacsson a,b, *, Bengt Lagerkvist d , Ulla Holck b , Christian Gold b,c a Rett Center, Ja ¨mtland County Council, O ¨ stersund, Sweden b Department of Communication and Psychology, Aalborg University, Denmark c Grieg Academy Department of Music, University of Bergen, Norway d Department of Woman and Child Health, Umea University, Sweden 1. Introduction Rett syndrome (RTT) is a neurodevelopmental disorder with devastating consequences (Hagberg, Hanefeld, Percy, & Skjeldal, 2002; Neul et al., 2010). The condition affects mostly females, and RTT is recognised as having the same prevalence of 1 per 10,000 newborn females in several populations all over the world. Most cases of RTT are caused by different kinds of mutations in a regulatory gene (MECP2) in the X-chromosome, leading to disruptions in the normal growth of neurons in the central nervous system (Amir et al., 1999; Clarke, Schanen, & Anvret, 2001). Twenty years of clinical and neurological research in Sweden and Great Britain have shown disturbances in brainstem autonomic function among all patients diagnosed with RTT who have undergone an assessment of brainstem autonomic function (Glaze & Schulz, 2001; Trevarthen & Burford, 2001). The brainstem is immature in RTT, sometimes functioning at the same level as that of a baby (Porges, Doussard-Roosevelt, Portales, & Greenspan, 1996), and may stay immature throughout life (Kerr & Witt Engerstro ¨ m, 2001). Many of the characteristic features evolve due to immaturity of the brain in RTT, as summarised in the Fro ¨ so ¨ Declaration (Julu et al., 2008). Research in Developmental Disabilities 34 (2013) 788–794 A R T I C L E I N F O Article history: Received 31 August 2012 Received in revised form 19 October 2012 Accepted 24 October 2012 Available online 5 December 2012 Keywords: Rett syndrome (RTT) Communication Music Autonomic nervous system Emotions Facial expressions Facial Action Coding System A B S T R A C T Rett syndrome (RTT) is a neurodevelopmental disorder, including autonomic nervous system dysfunctions and severe communication impairment with an extremely limited ability to use verbal language. These individuals are therefore dependent on the capacity of caregivers to observe and interpret communicative signals, including emotional expressions. People in general, including therapists tend to focus on changes in facial expressions to interpret a person’s emotional state or choices, but with this population it is difficult to know if the interpretations are correct. The aims of this study were to investigate if the Facial Action Coding System (FACS) could be used to identify facial expressions, and differentiate between those that expressed emotions and those that were elicited by abnormal brainstem activation in RTT. The sample comprised 29 participants with RTT and 11 children with a normal developmental pattern, exposed to six different musical stimuli during non-invasive registration of autonomic brainstem functions. The results indicate that FACS makes it possible both to identify facial expressions and to differentiate between those that stem from emotions and those caused by abnormal brainstem activation. This knowledge may be a great help to an uninitiated observer, who otherwise might incorrectly interpret the latter as an expression of emotion. ß 2012 Elsevier Ltd. All rights reserved. * Corresponding author at: Rett Center, Box 601, 832 23 Fro ¨so ¨n, Sweden. Tel.: +46 63154812; fax: +46 63154500. E-mail address: marith.bergstrom-isacsson@jll.se (M. Bergstro ¨ m-Isacsson). Contents lists available at SciVerse ScienceDirect Research in Developmental Disabilities 0891-4222/$ – see front matter ß 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ridd.2012.10.011