A modified version of the Bayley Scales of Infant Development-II for cognitive matching of infants with and without Down syndrome

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1 554 Joural of Itellectual Disability Research volume 52 part 6 pp jue 2008 doi: /j x Brief report A modified versio of the Bayley Scales of Ifat Developmet-II for cogitive matchig of ifats with ad without Dow sydrome D. G. Moore, 1 J. E. Goodwi 1 & J. M. Oates 2 1 Istitute for Research i Child Developmet, School of Psychology, Uiversity of East Lodo, Lodo, UK 2 Cetre for Childhood, Developmet ad Learig, Ope Uiversity, Milto Keyes, UK Abstract Backgroud May measures of ifats early cogitive developmet, icludig the BSID-II (The Bayley Scales of Ifat Developmet), mix together test items that assess a umber of differet developmetal domais icludig laguage, attetio, motor fuctioig ad social abilities, ad some items cotribute to the assessmet of more tha oe domai. Cosequetly, the scales may lead to uder- or over-estimates of cogitive abilities i some cliical samples ad may ot be the best measure to use for matchig purposes. Method To address this issue we created a modified form of the BSID-II (the BSID-M) to provide a purer assessmet of the geeral cogitive capacities i ifats with Dow sydrome (DS) from 6 to 18 moths of age. We excluded a umber of items that implicated laguage, motor, attetioal ad social fuctioig from the origial measure. This modified form was admiistered to 17 ifats with Correspodece: Professor Derek Moore, Istitute for Research i Child Developmet, Departmet of Psychology, Uiversity of East Lodo, Romford Road, Lodo E15 4LZ, UK ( d.g.moore@uel.ac.uk). Dow sydrome whe 6, 12 ad 18 moths old ad to 41 typically developig ifats at 4, 7 ad 10 moths old. Results The results suggested that the modified form cotiued to provide a meaigful ad stable measure of cogitive fuctioig ad revealed that DS ifats may score margially higher i terms of geeral cogitive abilities whe usig this modified form tha they might whe usig the stadard BSID-II scales. Coclusios This modified form may be useful for researchers who eed a purer measure with which to match ifats with DS ad other ifats with itellectual disabilities o cogitive fuctioig. Keywords Bayley scales, BSID-M, cogitio, Dow sydrome, ifats, matchig Itroductio The Bayley Scales of Ifat Developmet (BSID & BSID-II, Bayley 1969, 1993) provide a metal developmet idex or facet, comprised of items which are iteded to have predomiatly cogitive

2 555 Age i Moths Ageidays M SD Rage Table 1 Age of participats at each compariso poit Compariso oe Ifats with Dow sydrome Ifats with typical developmet Compariso two Ifats with Dow sydrome Ifats with typical developmet Compariso three Ifats with Dow sydrome Ifats with typical developmet cotet. If we are to explore potetial dissociatios betwee cogitive developmet ad other domais of fuctioig i ifats with itellectual disabilities (IDs), it is essetial that we develop relatively pure measures of cogitive abilities that we ca use for matchig purposes. Ufortuately, may measures of ifats early cogitive developmet, icludig the BSID-II, mix together test items that assess a umber of differet developmetal domais icludig laguage, attetio, motor fuctioig ad social abilities, ad some items cotribute to the assessmet of more tha oe domai. Specifically, some items which are icluded i the cogitive subscale are also used to assess social egagemet, ad success o some cogitive items may be costraied by a ifat s fie tued motor fuctioig or by abilities to atted to the task rather tha their geeral abilities for plaed actio or represetatio, which may be the area o which researchers wish to match. Thus, while these scales give useful idicatios of the geeral developmetal level of a ifat, it is ot always clear that the cogitive subscale score that emerges is a pure eough idex of cogitive fuctioig to be safely employed as a matchig measure (Moore et al. 2002). Aother problem whe usig the BSID-II scales with ifats with developmetal difficulties is i kowig at which poit i the scales to start (Gauthier et al. 1999). This ca sometimes mea that ifats with IDs are admiistered more items tha typically developig (TD) childre, which may lead to particular problems for ifats with Dow sydrome (DS) whe cosidered i light of mastery motivatio problems ( Wishart & Duffy 1990; Gilmore et al. 2003). This paper reports our iitial attempt to develop a modified versio of the Bayley II that is simpler to admiister ad that might provide a less cofouded assessmet of cogitive level whe beig used as a matchig measure. We refer to this as the BSID-M. The itetio was to develop a measure of cogitive fuctioig that would be familiar to researchers i admiistratio, ad retai its coheret structure, but would specifically focus o cogitive capacities, ad allow researchers to be more cofidet whe matchig ifats with ad without DS o cogitive abilities. This may the allow researchers to reveal with more clarity those areas of fuctioig that are spared or impaired relative to cogitive level (Rast & Meltzoff 1995; Chapma & Hesketh 2000; Fidler 2005). To explore these issues we admiistered this BSID-M logitudially to a group of ifats with DS whe aged 6, 12 ad 18 moths. To select our compariso ages, we used orms from Table 1 i Rauh et al. (1996). Their data idicated that: 6-moth-old ifats with DS would be expected to have metal ages equivalet to a 4-moth-old TD ifat; 12-moth-old ifats with DS have metal ages aroud 7 moths; ad 18-moth-old ifats would be expected to perform at the level of a 10-moth-old ifat. Our first questio was whether we would get a meaigful profile of resposes that would allow us to compare groups. Our secod questio was whether the levels of stability of the measure were

3 556 comparable with the BSID-II. Our third questio was whether we would obtai levels of performace i the ifats with DS that were similar to the TD ifats. Method Participats Sevetee childre with DS ad 41 TD ifats took part i the study. The ifats with DS were tested whe aged 6, 12 ad 18 moths ad the TD ifats were tested whe aged 4, 7 ad 10 moths. Te ifats with DS ad 15 TD ifats comprised a fully logitudial sample ad were tested at all three compariso poits. Details of the sample are provided i Table 1. Participats were recruited through health professioals ad by advertisemets. The demographics of the two groups were very similar (see Table 2). Selectio of items Oly items that cotributed to the cogitive facet of the BSID-II up to 12 moths developmetal age (DA) were cosidered for admiistratio. We excluded all items that also cotributed to the social facet, apart from five social items 1 which we retaied to facilitate egagemet with the task. Also we excluded items from the cogitive scale if they also cotributed to the laguage facet ad ay item for which the motor demads might be particularly taxig. I additio, we excluded items that assessed attetioal cotrol such as habituatio or the trackig of objects (i light of Zelazo & Stack 1997). We also excluded items that depeded o hearig. Other selected items were also excluded after cosultatio with experieced colleagues i the field. Cocers were raised about the BSID-II object cocept tasks ivolvig the heavy plastic cups provided, which we have repeatedly foud difficult for youg ifats to maipulate, ad that may act as a uecessary costrait o ifats plaed actio abilities. The items we excluded ad retaied are listed i Table 3. 1 These items were ot used i the calculatio of the fial cogitive scores. Table 3 groups the items accordig to the DA at which they would be expected to be ed o the full BSID-II scales. Note that may items o the BSID-II are derived from the admiistratio of a sigle structured task. For example, by presetig the red cubes oe allocates scores for a umber of items that relate to this presetatio, eve those items that are below the DA tested. Thus, for the older ifats reported here, we are able to report their success rates o items that relate to the level at which they were beig assessed ad also at youger levels. Importatly, while this gives the impressio that the older ifats were admiistered a loger test, this was ot i fact the case, ad the procedure did ot take much loger for the older tha the youger ifats. We were left with a battery of items that examied ifat s abilities to use plaed meaigful actios but that did ot deped o hearig, laguage productio, require overly precise motor coordiatio, or require chages i attetioal focus. Procedure The BSID-M took up to 15 mi to admiister. Ifats were typically seated o the mother s lap or i a high chair. The whole sessio was recorded o video for later off-lie cofirmatio of the codig. As with the admiistratio of the full BSID-II, a elemet of discretio was allowed i how items should be admiistered. For example, items could be omitted if the experimeter judged that failure o earlier items showed that further testig o that set would be uproductive. Results Table 4 shows the success rates achieved by ifats with ad without DS o each item at each of the age compariso poits. Examiatio of Table 4 shows that there was cosiderable cosistecy i levels of performace across items from withi each developmetal level for each age group. The oly item that appeared to be out of lie with items i the developmetal bracket was item 40 carries rig to mouth which for the two older compariso poits showed far lower levels of success. This may

4 557 Table 2 Characteristics of ifats ad their families Ifat Family Group (first bor) Geder Mother s Mea age i years (SD) Mothers Ethicity Mothers Relatioship Qualificatios status Father s Mea age i years (SD) Best SES of Father or mother* Dow sydrome 17 (9) 11 male 6 female Typically developig 41 (24) 24 male 17 female (5.5) 12 = white 1 = Idia-Asia 1 = afro-carribea 3 = mixed race 30.4 (6.0) 28 = white 7 = Idia-Asia 5 = afro-carribea 1 = mixed race Noe = 1 GCSE = 4 Vocatioal = 9 A level = 1 Degree = 2 Noe = 0 GCSE = 7 Vocatioal = 19 A level = 5 Degree = 10 Married/Parter = 14 Sigle = 3 Married/Parter = 35 Sigle = (4.4) II = 9 IIIN = 7 IIIM = (5.11) I = 1 II = 25 IIIN = 9 IIIM = 5 Other = 1 * SES = Socio-ecoomic status; I = Professioal; II = maagerial/techical; IIIN = skilled o-maual; IIIM = skilled maual. GCSE: UK age 16 school leavig qualificatios; Vocatioal: school or post-school semi-skilled vocatioal traiig; A level: UK advaced, age 18, school/college qualificatio; Degree: Bachelors level or above UK uiversity degree qualificatio.

5 558 Table 3 Items retaied ad excluded from the BSID-II (The Bayley Scales of Ifat Developmet) cogitive facet together with reaso for exclusio Developmetal age (moths) Items retaied Cogitive facet items excluded Reaso for exclusio 2 15 Eyes follow rig Eyes follow rig i circle/arc Attetio 24 Head follows rig 20 React to disappearace of face Social 25 Regards cube for 3 s 23 Glaces from bell to rattle Motor Habituatio to visual stimulus Attetio 30 Turs head to soud Hearig 32 Eyes follow rollig ball Attetio 3 37 Maipulates rig 29 Novelty after habituatio Attetio 38 Reaches for suspeded rig 34 Ispects ow hads Motor 39 Grasps suspeded rig 35 Plays with rattle Motor/hearig 40 Carries rig to mouth 36 Eyes follow rod Motor/attetio 42 Reaches for cube 41 Approaches mirror* Social 47 Display awareess of surroudigs Attetio/social 4 43 Reaches persistetly 46 Fixates o disappearace of ball Attetio 44 Uses had-eye i reachig 49 Smiles at mirror image* Social 45 Picks up cube 50 Respods playfully to mirror image* Social 48 Plays with strig 51 Regards pellet Motor/accommodatio 52 Bags i play Pers. comm./motor 55 Lifts iverted cup Motor 5 53 Reaches for 2d cube 54 Trasfers object to had Motor 57 Picks up cube deftly 56 Looks for falle spoo Pers. comm. 58 Retais 2 cubes for 3 s 59 Maipulates bell Motor 60 Atteds to scribblig 6 62 Pulls strig adaptively 64 Cooperates i game* Social 65 Retais 2 of 3 cubes for 3 s 66 Rigs bell purposely Hearig 67 Lifts cup by hadle Motor 69 Looks at pictures i book Attetio 7 74 Puts 1 cube i cup 72 Looks for cotets of box Motor 8 75 Attempts to secure 3 cubes 73 Turs pages of book Motor 79 Figers hole i pegboard 77 Pushes car Motor 80 Removes lid from box Motor 9 82 Suspeds rig by strig 83 Pats toy i imitatio* Motor/social 86 Puts 3 cubes i cup 84 Fids oe object Motor 85 Removes pellet from bottle Motor Retrieves toy from clear box 89 Puts six beads i box Motor Scribbles spotaeously 92 Closes roud cotaier 95 Puts 9 cubes i cup Places 1 peg repeatedly 96 Fids toy uder reversed cups Motor-heavy cups 93 Places circle i pik form board 97 Builds tower of 2 cubes 98 Places pegs i 70 s * These items were retaied to facilitate social egagemet but did ot cotribute to the total score. reflect the differet strategies for explorig objects that are adopted by youger ad older ifats, ad suggests that this item is oly appropriate as a idicator of cogitive level for youger ifats. I order to examie stability over time i idividual differeces we examied the profiles of the logitudial subsample ad correlated the umber of successful items at compariso poit oe with

6 559 Table 4 Showig umber of ifats admiistered each item ad success rate o each item at each compariso poit Compariso oe (DS = 6 moths; TD = 4 moths) Compariso two (DS = 12 moths; TD = 7 moths) Compariso three (DS = 19 moths; TD = 10 moths) DS TD DS TD DS TD Developmetal age (moths) Item 2 15 Eyes follow rig Head follows rig Regards cube for 3 s Maipulates rig Reaches for suspeded rig Grasps suspeded rig Carries rig to mouth Reaches for cube Reaches persistetly Uses had-eye reachig Picks up cube Plays with strig Reaches for 2d cube Picks up cube deftly Retais 2 cubes for 3 s Atteds to scribblig Pulls strig adaptively Retais 2 of 3 cubes for 3 s * 7 74 Puts 1 cube i cup 10 70* Secures 3 cubes Figers hole i pegboard Suspeds rig by strig * Puts 3 cubes i cup Retrieves from clear box I Scribbles spotaeously Closes roud cotaier Puts 9 cubes i cup Places 1 peg repeatedly Places circle i board Builds tower of 2 cubes Places pegs i 70 s * Sigificat associatio with group (Chi-square p < 0.05). DS, Dow sydrome; TD, typically developig. that at time two, ad total items at compariso two with total at compariso three. For compariso oe vs. two, the correlatios were for DS, Spearma s Rho = 0.41, NS; for TD ifats, Spearma s Rho = 0.54, p < For compariso two vs. three, the correlatios were for DS, Spearma s Rho = 0.40, NS; for TD ifats, Spearma s Rho = 0.65, p < Thus both groups of ifats showed reasoable stability over time. The 6-moth-old ifats with DS ad the TD ifats achieved a similarly high level of success o the items from the 2-moth developmetal period. However, for items from the 3- ad 4-moth developmetal period, 6-moth-old ifats with DS

7 560 teded to show higher levels of performace tha the 4-moth-old TD ifats. I terms of the total umber of items ed at compariso oe (DS = 6 moths; TD = 4 moths), DS ifats ed betwee 3 ad 13 items admiistered, Mea = 7.9, SD = 3.3. TD ifats showed a similar rage of items ed (0 13) with Mea = 4.6, SD= 3.3. A t-test showed there to be a sigificat differece i the umber of items ed by the two groups, t = 2.59, d.f. = 30, p = 0.016, 2-tailed). For compariso two (DS = 12 moths; TD = 7 moths) the majority of ifats i both groups ed items i the 3- ad 4-moth sets. DS ifats ed betwee 8 ad 18 of the items admiistered, Mea = 12.7, SD= 2.5. TD ifats showed a wider rage of items ed (rage 3 16) with Mea = 10.9, SD= 3.4. At-test showed there to be o sigificat overall differece betwee the groups (t = 1.68, d.f. = 35, p = 0.1, 2-tailed), although o item 74 (puts oe cube i cup) there was a sigificat associatio betwee diagosis ad success with more ifats with DS succeedig o this item (Chi-square = 7.01, d.f. = 1, p = 0.008). For compariso three (DS = 18 moths; TD = 10 moths), DS ifats ed betwee 7 ad 24 of the relevat items admiistered, Mea = 15.3, SD = 4.8. TD ifats showed a similar rage of items ed (rage 5 19) with Mea = 13.5, SD = 3.2. At-test showed there to be o sigificat differece betwee the groups (t = 1.59, d.f. = 49, p = 0.12, 2-tailed). There were sigificat associatios of diagosis ad performace o two items at this compariso poit. Item 65 where more TD ifats were successful (Chi-square = 5.97, d.f. = 1, p = 0.014) ad item 82 where more ifats with DS were successful (Chi-square = 4.63, d.f. = 1, p = 0.031). Discussio The data suggest that the modified versio of the BSID-II is a meaigful measure of cogitive level with reasoable cosistecy withi groups. Furthermore, correlatios betwee the first compariso poit ad subsequet poits, ragig from 0.40 to 0.65, while ot sigificat for the small sample of ifats with DS, were comparable with previous reports. Specifically, Harris et al. (2005) reported for the full BSID, i a at-risk sample, a correlatio across admiistratios of Similarly, Niccols & Latchma (2002) reported stability correlatios i at-risk samples of 0.37 ad Thus our data suggest that this modified scale is comparable i stability to the full BSID-II. I terms of use for matchig the fidigs idicate that youg ifats with DS may have higher cogitive levels tha suggested from iteratioal orms derived from the BSID published by Rauh et al. (1996). The 6-moth-old ifats with DS i particular performed sigificatly better tha the 4-moth-old TD cotrol ifats. The data suggest that if we wish to match o DA o the basis of our BSID-M, we might wish to match 6-moth-old ifats with DS with 5-moth-old TD ifats. With the two older comparisos the DS ifats did ot do sigificatly better tha the TD ifats. However, the DS ifats teded to show higher scores, ad it might be recommeded that for matchig purposes 12-moth-old ifats with DS would be matched with 8-moth-old TD ifats ad 18-moth-old DS ifats with 12-moth-old TD ifats. Of course util a subsequet study is performed i which the same ifats are admiistered both the BSID-II ad BSID-M i couterbalaced order we caot coclude that the BSID-II sigificatly uderestimates the cogitive abilities of ifats with DS. However, this iitial study at least suggests there is some mileage i usig a modified versio for detailed matchig purposes. The developmet of simple measures that more clearly assess cogitive level may facilitate the more efficiet collectio of data i large scale logitudial studies i ifacy ad allow developmetal relatios betwee domais to be tested with more precisio. Matchig o this ew measure would allow researchers to cofidetly ivestigate attetio, laguage, motor ad social developmet i ifats with DS without fear that their matchig procedure has bee cofouded. While this paper presets oly a prelimiary attempt to modify the BSID-II to be used as a better matchig measure, it highlights the importace of adoptig a approach that recogises the limitatios of all tests that were desiged to assess geeral developmetal levels for matchig purposes. It remais to be see whether this scale will prove useful for matchig cogitive

8 561 abilities with other ifats at developmetal risk as part of wider compariso studies (Hodapp 2004). Ackowledgemets We would like to thak the mothers ad ifats who participated i our studies ad ackowledge the ESRC for fiacial support (Research Grat: R ). The first author was also partly aided by NiH Grat DA Refereces Bayley N. (1969) BSID: Birth to TwoYears. Psychological Corporatio, New York. Bayley N. (1993) BSID-II. Psychological Corporatio, New York. Chapma R. S. & Hesketh L. J. (2000) Behavioral pheotype of idividuals with Dow sydrome. Metal Retardatio ad Developmetal Disabilities Research Reviews 6, Fidler D. J. (2005) The emergig dow sydrome behavioral pheotype i early childhood implicatios for practice. Ifats adyoug Childre 18, Gauthier S. M., Bauer C. R., Messiger D. S. & Closius J. M. (1999) The Bayley Scales of Ifat Developmet II: where to start? Joural of Developmetal ad Behavioral Pediatrics 20, Gilmore L., Cuskelly M. & Hayes A. (2003) A comparative study of mastery motivatio i youg childre with Dow s sydrome: similar outcomes, differet processes? Joural of Itellectual Disability Research 47, Harris S. R., Meges A. M., Backma C. L. & Hayes V. E. (2005) Stability of the Bayley II Scales of Ifat Developmet i a sample of low-risk ad high-risk ifats. Developmetal Medicie ad Child Neurology 47, Hodapp R. M. (2004) Behavioral pheotypes: goig beyod the two-group approach. Iteratioal Review of Research o Metal Retardatio 29, Moore D. G., Oates J. M., Hobso R. P. & Goodwi J. E. (2002) Cogitive ad social factors i the developmet of ifats with Dow sydrome. Dow Sydrome Research ad Practice 8, Niccols A. & Latchma A. (2002) Stability of the Bayley metal scale of ifat developmet with high risk ifats. British Joural of Developmetal Disabilities 48, Rast M. & Meltzoff A. N. (1995) Memory ad represetatio i youg childre with Dow sydrome: explorig deferred imitatio ad object permaece. Developmet ad Psychopathology 7, Rauh H., Schellhas B., Goeggerle S. & Muller B. (1996) Diachroic developmetal assessmet of metally hadicapped youg childre. I: Early Childhood Itervetio: Theory, Evaluatio ad Practice (eds M. Brambrig, H. Rauh & A. Beelma), pp De Gruyter, Berli, New York. Wishart J. G. & Duffy L. (1990) Istability of performace o cogitive tests i ifats ad youg childre with Dow s Sydrome. British Joural of Educatioal Psychology 60, Zelazo P. R. & Stack D. M. (1997) Attetio ad iformatio processig i ifats with Dow sydrome. I: Attetio, Developmet ad Psychopathology (eds J. A. Burack & J. T. Es), pp Guilford Press, New York. Accepted 17 March 2008