language and academic abilities in children with selective mutism
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Infant and Child DevelopmentInf. Child. Dev. 18: 271290 (2009)
Published online 18 May 2009 in Wiley InterScience
(www.interscience.wiley.com). DOI: 10.1002/icd.624
Language and Academic Abilities inChildren with Selective Mutism
Matilda E. Nowakowskia, Charles C. Cunninghamb,Angela E. McHolmb, Mary Ann Evansc, Shannon Edisonc,Jeff St. Pierred, Michael H. Boyleb and Louis A. Schmidta,aDepartment of Psychology, Neuroscience and Behaviour, McMaster University,Hamilton, Ont., CanadabDepartment of Psychiatry and Behavioural Neurosciences, McMaster University,Hamilton, Ont., CanadacDepartment of Psychology, University of Guelph, Guelph, Ont., CanadadChild and Parent Resource Institute (CPRI), London, Ont., Canada
We examined receptive language and academic abilities inchildren with selective mutism (SM; n5 30; M age5 8.8 years),anxiety disorders (n5 46; M age5 9.3 years), and communitycontrols (n5 27; M age5 7.8 years). Receptive language andacademic abilities were assessed using standardized testscompleted in the laboratory. We found a significant group bysex interaction for receptive vocabulary scores such that withinfemales, the SM and mixed anxiety groups had significantlylower receptive vocabulary scores than community controls. Wealso found that children with SM and children with anxietydisorders had significantly lower mathematics scores thancommunity controls. Despite these differences in mathematicsand receptive vocabulary performance, children with SM andchildren with anxiety disorders still performed at age-levelnorms, while more children in the community control groupperformed above age-level norms. Findings suggest that despitetheir speaking inhibition in the school setting, children with SMare still able to attain the receptive vocabulary and academicabilities that are expected at their age levels. Copyright r 2009John Wiley & Sons, Ltd.
Selective mutism (SM) is a disorder in which children fail to speak in certainsituations, usually outside the home, despite speaking normally in othersituations, usually the home (APA, 1994). Although SM is most commonlydiagnosed upon school entry when the demands for children to speak outside ofthe home increase, SM usually first appears in the preschool years (Cunningham,
*Correspondence to: Louis A. Schmidt, Department of Psychology, Neuroscience andBehaviour, McMaster University, Hamilton, Ont., Canada L8S 4K1. E-mail: firstname.lastname@example.org
Copyright r 2009 John Wiley & Sons, Ltd.
McHolm, Boyle, & Patel, 2004; Steinhausen & Juzi, 1996). The prevalence of SM isestimated at between 0.7% and 2% of children (Bergman, Piacentini, &McCracken, 2002; Elizur & Perednik, 2003; Kopp & Gillberg, 1997; Kumpulainen,Rasanen, Rasska, & Somppi, 1998), with a higher prevalence for immigrantchildren (Elizur & Perednik, 2003). SM is usually more common in girls than inboys with a ratio ranging between 1.2:1 and 2.6:1 (Black & Uhde, 1995; Dummitet al., 1997; Kristensen, 2000; Steinhausen & Juzi, 1996) and often comorbid withother disorders, including anxiety disorders (Bergman et al., 2002; Cunninghamet al., 2004; Cunningham, McHolm, & Boyle, 2006; Dummit et al., 1997; Manassiset al., 2007; Steinhausen & Juzi, 1996; Vecchio & Kearney, 2005; Yeganeh, Beidel, &Turner, 2006; Yeganeh, Beidel, Turner, Pina, & Silverman, 2003), communicationdisorders (Dummit et al., 1997), developmental delay (Elizur & Perednik, 2003;Steinhausen & Juzi, 1996), and oppositional defiant disorder (Steinhausen & Juzi,1996; Yeganeh et al., 2006). However, the aetiology of SM is not well understooddue to the heterogeneous presentation of the disorder, and the fact that it appearsto be influenced by many factors including, genetics, temperament, psychologicalwell-being, attainment of developmental milestones and social factors (Cohan,Price, & Stein, 2006).
There is much debate about the conceptualization and classification of SM,which is currently found under the Other Disorders of Childhood category inthe Diagnostic and Statistical Manual 4th Edition (APA, 1994). Some researchershave argued that SM should be viewed as a distinct anxiety disorder (Anstendig,1999; Sharp, Sherman, & Gross, 2007; Vecchio & Kearney, 2005) or an extremevariant of social phobia (Yeganeh et al., 2006). This view is supported by simi-larities in the definition of SM and social phobia, both characterized by an intensefear of social situations in which embarrassment may occur as well as a lack ofinhibition and anxiety in the home setting (APA, 1994). As well, a large numberof studies have found that SM co-occurs at high rates with anxiety disorders,especially social phobia. For instance, both Vecchio and Kearney (2005) andDummit et al., (1997) using sample sizes of 15 and 50 respectively, reported that100% of the selectively mute children in their studies met the diagnostic criteriafor social phobia and around 50% of the selectively mute children met the criteriafor a second anxiety disorder. Another study by Black and Uhde (1995) foundthat 97% of the children who were diagnosed with SM met the diagnostic criteriafor social phobia.
Longitudinal studies have also found that individuals with a childhoodhistory of SM experienced shyness and symptoms of social anxiety asadults and adolescents despite being cured from their SM (Joseph, 1999). Aswell, family studies have found that parents of children with SM havehigher rates of anxiety disorders, especially social phobia (Black & Uhde,1995), compared with parents of normally developing children (Kumpulainen,2002).
Numerous researchers (Black & Uhde, 1995; Dummit et al., 1997) have high-lighted the similarities between children with SM and children classified as be-haviourally inhibited. According to Kagan, Reznick, & Snidman (1987), a failureor reluctance to speak is one of the defining characteristics of behavioural in-hibition. Studies have found that parents of children with SM retrospectivelyreport that their children were always shy from their first years of life (Garcia,Freeman, Francis, Miller, & Leonard, 2004). Steinhausen and Juzi (1996) reportedthat 85% of the children with SM in their sample exhibited high levels of shyness.Given that there is evidence that children with behavioural inhibition are at anincreased risk for the development of anxiety disorders (Oberklaid, Sanson,
M.E. Nowakowski et al.272
Copyright r 2009 John Wiley & Sons, Ltd. Inf. Child. Dev. 18: 271290 (2009)DOI: 10.1002/icd
Pedlow, & Prior, 1993), many researchers have suggested that behavioural in-hibition may be an early predictor of SM.
Despite the similarities in aetiology and presentation between SM and anxietydisorders (especially social phobia), SM differs from anxiety disorders in that it isassociated with higher rates of expressive language difficulties and develop-mental delays. Steinhausen and Juzi (1996) found that 38% of the children withSM in their sample exhibited problems with expressive language, articulation,and stuttering. Similarly, McIness, Fung, Manassis, Fiksenbaum, & Tannockand(2004) reported that compared with children with social anxiety, the speech ofchildren with SM was linguistically simpler and shorter. In terms of generaldevelopmental delays, Kristensen (2000) found that 68% of their sample ofchildren with SM met the criteria for a developmental delay. Thus, difficulties inexpressive language abilities as well as general developmental delays appear tobe distinguishing factors between SM and social phobia. Further research com-paring children with SM to those with anxiety disorders is necessary to betterunderstand the similarities and differences in how the disorders present them-selves and impact childrens functioning.
One area of importance in terms of its impact on childrens functioning iswhether SM affects childrens performance in school. Verbal participation atschool is considered an important part of the learning process (Daly & Korinek,1980). Given that SM is characterized by a lack of speech, it is reasonable tosuspect that children with SM may score lower on tests of academic abilities dueto their inability to ask questions when they require clarification. This inabilitymay in turn result in a lack of homework completion and an accumulation ofdeficits due to not receiving the clarification necessary early on and falling be-hind as the material becomes more difficult. As well, much incidental learningoccurs in the school setting through social and collaborative conversations withpeers. Owing to their lack of speech, children with SM may miss out on suchconversations.
Past studies investigating academic abilities in children with SM have yieldedvarying results. For example, some researchers have reported that children withSM perform significantly lower than community controls on academic measures(Bergman et al., 2002; Kristensen & Oerbeck, 2006; Schwartz, Freedy, & Sheridan,2006), especially language abilities (Manassis et al., 2007; McInnes et al., 2004). Incomparison, other studies have found no differences between children with SMand community controls (Cunningham et al., 2004). The discrepancies betweenstudies may be explained by three factors: (1) the use of different standardizedmeasures, (2) the utilization of different testing methods such that some studiesrelied on methods that required verbal responses while others used methods thatallowed for non-verbal responses, and (3) different foci of interest in terms ofacademic skill sets.
In a sample of 52 children with SM and 52 community controls, Cunninghamet al., (2004) reported no differences between groups on standardized tests of mathand reading or on teacher reports of childrens math, reading, and overall aca-demic abilities. On the other hand, Manassis