The diagnosis of autism and Asperger syndrome: findings from a survey of 770 families

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1 The dignosis of utism nd Asperger syndrome: findings from survey of 770 fmilies Ptrici Howlin*, Deprtment of Psychology, St George s Hospitl Medicl School, London; Ann Asghrin, Deprtment of Psychology, Royl Hollowy College, Eghm, Surrey, UK. *Correspondence to first uthor t bove ddress. As prt of wider survey of prents of children with utistic spectrum disorders in the UK, the dignostic experiences of 614 prents of children with utism nd 156 with Asperger syndrome were compred. Although the ges of the children in the two groups were very similr t the time of the survey, prents of children given dignosis of Asperger syndrome hd experienced significntly longer delys nd greter frustrtion in obtining dignosis thn those with child with utism. In the utism group the verge ge when dignosis ws confirmed ws round 5.5 yers; in the Asperger group it ws 11 yers. Prents of children with dignosis of utism were generlly wre of problems in their child s development by 18 months of ge; in the Asperger group concerns emerged lter, t round 30 months of ge. Initil worries in both groups centred round bnorml socil development but prents of children with Asperger syndrome were less likely to hve noted communiction problems. Stereotyped or repetitive behviours were not prominent in the erly yers in either group. Despite the problems inherent in dt collected by postl survey, mny of the findings of this study re supported by other reserch. The prcticl implictions of delyed dignosis, especilly in the cse of more ble children with Asperger syndrome re discussed. Despite mjor dvnces in understnding the nture nd possible cuses of utism-relted disorders over recent yers (Biley et l. 1996) erly dignosis is still reltively rre (Bron-Cohen et l. 1996). Moreover, lthough positive experience of dignostic procedures cn hve significnt impct on fmilies (Quine nd Phl 1987, Woolley et l. 1989, Cottrell nd Summers 1990, Leff nd Wlizer 1992, Stllrd nd Lenton 1992), mny prents of children with utism remin fr from stisfied with this process (Smith et l. 1994, Howlin nd Moore 1997). Difficulties in obtining dignosis cn be prticulrly mrked when the child s disbilities re less evident. Thus, wheres child with obvious delys in lnguge nd cognition my be dignosed reltively erly in life, clinicl experience suggests tht dignosis my be considerbly delyed for children whose disbilities re more subtle. This is often the cse, for exmple, for children with Asperger syndrome, who by definition (Interntionl Clssifiction of Diseses [ICD-10], WHO 1992; Dignostic nd Sttisticl Mnul of Mentl Disorders [DSM-IV], Americn Psychitric Assocition 1994), do not show mrked cognitive or lnguge delys. Motor nd other erly developmentl milestones re usully norml nd indeed in some cses, children s precocious vocbulry nd prticulr knowledge of certin topics my give the impression tht they re very developmentlly dvnced. Prents nxieties my be dismissed by professionls s being without foundtion, or behviourl problems my be ttributed to indequte prenting. Alterntively, non-utism spectrum dignoses such s ttention deficit disorder, miniml brin dmge, emotionl nd behviourl problems, or schizoid personlity disorder (Wolff nd McGuire 1995) my be suggested. Problems in obtining correct dignosis for child with Asperger syndrome re often further excerbted by the fct tht professionls themselves disgree bout the criteri for dignosis (Ghziuddin et l. 1992, Klin nd Volkmr 1998) nd clinicins cn use the term in different wys. In recent survey of lmost 1300 fmilies belonging to utism support groups in the UK, prents were sked bout their experiences in ttempting to obtin dignosis for their child (for detils see Howlin nd Moore 1997). Using dt obtined from tht survey, the present study exmined whether there were ny differences between the experiences of prents who hd received dignosis of Asperger syndrome for their child nd those who hd been given dignosis of utism. The principl hypothesis, bsed on the premise tht children with dignosis of Asperger syndrome would hve less severe cognitive nd linguistic disbilities thn those with dignosis of utism, ws tht prents in the former group would experience more difficulties in obtining dignosis. Thus, dignosis would be mde lter nd their stisfction with the dignostic process would be less. Severl other issues were lso explored: (1) The ge t which prents first becme concerned bout their child s development nd the problems tht gve rise to these concerns. Previous reserch hs suggested tht mny prents of children with utistic spectrum disorders hve serious concerns bout their child s development in the first yer of life (Volkmr et l. 1985, Gillberg et l. 1990, Johnson et l. 1992, Frith et l. 1993, Smith et l. 1994, Howlin nd Moore 1997). It lso ppers tht impirments in socil, ply, nd communiction skills re mong the erliest symptoms to be noted. (Gillberg et l. 1990, Frith et l. 1993, Smith et l. 1994, 834 Developmentl Medicine & Child Neurology 1999, 41:

2 Howlin nd Moore 1997, De Gicomo nd Fombonne 1998). However, there hve been no studies compring erly symptomtology in children with Asperger syndrome to tht in children with utism. (2) The reltive frequency of utism versus Asperger syndrome in different ge groups. A detiled epidemiologicl review by Fombonne (1998) indictes tht the prevlence of clssic utism is round 5.0 per live births. An dditionl 15 per live births hve relted disorders, giving totl rte of 20 per live births for utistic spectrum disorders (Wing 1993). Ehlers nd Gillberg (1993) suggest tht the prevlence of Asperger syndrome is much higher thn this, t 36 per live births. As no dt hve been systemticlly collected on the reltive rtes of the two disorders, the proportion of utism to Asperger dignoses in the present smple ws investigted. In ddition, s the specil interests nd bilities tht chrcterize Asperger syndrome re often less evident in the erly yers (Wing 1981), it ws predicted tht this dignostic lbel would occur less frequently in the younger children thn in older ge groups. (3) Dignosis of Asperger syndrome versus utism in different geogrphicl res. It is cler tht the distribution of services for children with utistic spectrum disorders vries cross the UK, with certin res hving higher levels of professionl expertize thn others (Howlin nd Moore 1997). The study therefore lso explored whether the dignosis of Asperger syndrome ws more likely to be given in some regions thn in others. Method QUESTIONNAIRE Full detils of the questionnire used, distribution methods, nd the geogrphicl spred of respondents cn be found in the rticle by Howlin nd Moore (1997). All the locl societies or prent support groups listed by the Ntionl Autistic Society t the time of the study were contcted. Forty-eight groups indicted tht they hd sufficient resources vilble to offer help nd 2488 questionnires were distributed vi their miling lists. Responses were received from 1371 fmilies, nd 1295 of these forms were fully completed. The overll rte of returns ws 55.1%. However, some fmilies belonged to two, or sometimes more support groups, nd hence hd received more thn one copy of the questionnire, so tht it ws not possible to clculte the true return rte. Moreover, mny of the lrger societies hd non-prent members (i.e. professionl subscribers) for whom the forms were clerly not pproprite. Thus, it cn be ssumed tht the proportion of fmilies who returned form ws higher thn 55%. The questionnire covered the ge t which prents first becme concerned bout their child s development; the principl resons for these concerns; the ge t which help ws sought; the professionl(s) seen; the frequency of nd ges t further referrls; the finl dignosis obtined; nd generl stisfction with dignostic nd support services. SUBJECTS Out of the 1295 completed questionnires, 614 prents (47.4%) hd been given cler dignosis of utism for their child, nd 156 (12.0%) n unequivocl dignosis of Asperger syndrome. A further 112 subjects (8.6%) hd mixed Asperger/utism dignosis, often combined with dditionl lbels such s lnguge dely nd/or lerning disbility 346 (26.7%) hd dignosis of utistic trits or tendencies (gin sometimes in conjunction with other problems such s lerning disbility). The remining 5% hd mixture of different dignoses, including lnguge disorder, lerning disbilities or not known (for detils see Howlin nd Moore 1997). For the purpose of the present pper, only those with single dignosis of either utism or Asperger syndrome were included. The rtio of children with utism to those with Asperger syndrome ws 3.9:1.0 AGE AND SEX DISTRIBUTION There ws no significnt difference in the verge ges of the two groups t the time of the survey (utism group yers, SD 9.73 yers, rnge 2 to 48 yers; Asperger group yers, SD 7.03 yers, rnge 3.06 to 49 yers; t=1.10, P=0.27). Group differences in sex distribution were lso nonsignificnt. Sixteen (10.3%) of the Asperger group were femle; 140 (89.7%) mle; in the utism group 109 (17.8%) were femle nd 505 (82.2%) mle (χ 2 =2.03, ns). This is equivlent to mle:femle rtio of 8.7:1.0 in the former nd 4.6:1.0 in the ltter group. The rtio for the utism group is similr to tht reported in other studies (Volkmr et l. 1993). Sex dt for Asperger syndrome hve not been collected systemticlly, but re reported s being somewhere between 4:1 nd 15:1 (Wing 1981, Tntm 1991, Ehlers nd Gillberg 1993) nd possibly even s high s 27:1 (Volkmr et l. 1993). Results DIAGNOSTIC DIFFERENCES Age when prents first becme concerned Asked when they hd first become concerned bout their child, prents in the Asperger group indicted tht this hd generlly been sometime during the child s third yer. In the utism group, worries typiclly begn round 18 months of ge (men ge in Asperger group 2.53 yers, SD 2.47 yers; men ge in utism group 1.52 yers, SD 1.06; t=7.68, P<0.001). As cn be seen from Tble I, over hlf of the prents in the utism group nd third of those in the Asperger group hd serious concerns by the child s second birthdy. However, proportiontely more prents in the ltter group did not become concerned until fter the ge of 5 yers (χ 2 =8.23, P<0.01). The verge ge of the child t which prents first sought Tble I: Age of child when prents first concerned Age of child (y) Autism Asperger (N=608) % (N=155) % < < < < < Informtion ws missing for six children with utism nd one with Asperger syndrome. Note when χ 2 comprisons were conducted these were bsed on proportions becuse the vlue of χ 2 is relted to smple size, nd when Ns re lrge this increses the risk of Type 1 errors. Dignosis of Autism nd Asperger Syndrome Ptrici Howlin nd Ann Asghrin 835

3 help ws 2.05 yers in the utism group (SD 1.92) nd 3.49 yers in the Asperger group (SD 2.61; t=7.73, P<0.00). The men time intervl between prents first becoming concerned nd seeking help ws 0.58 yers in the utism group (SD 1.03) nd 1.08 yers in the Asperger group (SD 1.45; t=4.99, P<0.001). Age when dignosis ws confirmed The verge ge t finl dignosis ws significntly higher in the Asperger group (men yers, SD 5.99, rnge 3.00 to yers) thn in the utism group (men 5.49 yers, SD 4.56 yers, rnge 1.00 to yers; t=12.77, P<0.001). Although this difference my be prtly due to the utism prents being wre of their children s problems erlier, the time tht elpsed between prents first becoming concerned nd finlly obtining dignosis ws fr longer in the Asperger group (men time gp in utism group 3.97 yers, SD 4.29; Asperger group 8.59 yers, SD 5.92; t=10.95, P<0.001). Twenty-six children in the utism group (4.3%) hd been dignosed by the ge of 2 yers but no child in the Asperger group ws dignosed before 3 yers. Overll, 67.2% of the utism group were dignosed by their fifth birthdy compred with only 17.0% of the Asperger group (χ 2 =49.28, P<0.001). In both groups number of individuls were dignosed extremely lte. Fifteen (9.8%) of the Asperger group nd 13 (2.1%) of the utism group were not dignosed until the ge of 20 yers or lter. Mny more were not dignosed until their mid-teens, but the proportion of lte dignoses (i.e. 15 yers or lter) ws higher in the Asperger group (77% compred with 5%; χ 2 =3.89, P<0.048). If individuls who were not dignosed until dulthood were excluded from the nlysis, the difference in men ge of dignosis between the utism nd Asperger groups remins (men ge in utism group 5.03 yers, SD 3.28; Asperger group 9.71 yers, SD 4.28; df=733 t=14.27, P<0.001). Individuls with dignosis of Asperger syndrome were lso dignosed significntly lter thn those given less precise dignoses, such s utism spectrum disorder or utistic tendencies, nd so on. In these ltter groups, men ge of dignosis ws 4.82 yers; SD 3.8 yers; t=11.02, P< For further detils see Howlin nd Moore Pttern of consulttions Tble II provides informtion on the pttern of dvice given to prents seeking dignosis over three seprte referrls. Children in the Asperger group were significntly older thn those in the utism group t ech referrl. The first professionls from whom prents sought help were their GP or helth visitor, lthough few initilly went to peditricin, nd severl fmilies sw vrious combintions of professionls. Fewer thn 10% of prents in either group were given dignosis t the first consulttion nd round hlf were referred for nother dignosis. Nine percent of the utism group nd 12% of the Asperger group were told to return if their concerns persisted but mny prents were ressured tht they should not worry or tht there ws no problem. There were no significnt group differences on ny of these vribles. A substntil mjority of both groups went on to seek further consulttion. Peditricins, child psychitrists, or psychologists were the professionls most commonly seen, lthough mny fmilies hd multidisciplinry ssessment. Fr more fmilies obtined dignosis t the second ssessment nd fewer were referred on. Nevertheless, more prents in the Asperger group continued to be ressured tht there ws nothing to worry bout (χ 2 =3.72, P<0.05). Either becuse no cler dignosis hd been given or becuse they were disstisfied with the dignosis they hd received, 59% of the utism prents nd 83% of the Asperger prents sought third dignostic consulttion. At this third consulttion, 60% or more fmilies were given dignosis nd only reltively smll proportion ws referred to yet nother consultnt. Agin, more prents in the Asperger group were told not to worry (χ 2 =4.19, P<0.05) despite the fct tht by this ge their children were ged, on verge, over 9 yers. Stisfction with the dignostic process Prents in the Asperger group were significntly less stisfied with the dignostic process thn those in the utism group (Mnn Whitney U test corrected for ties, z= 3.71, P<0.001; bsed on rtings of: 0 very stisfied ; 1 quite stisfied / neutrl, nd 2 not t ll stisfied ). There ws lso smll but significnt correltion between the length of time tken to Tble II: Action tken when prents sought dignostic consulttion Consulttion Ist 2nd 3rd Autism Asperger Autism Asperger Autism Asperger group group group group group group N=614 N=156 N=559 N=136 N=365 N=130 Men ge of child (SD) (1.92) (2.61) (2.26) (3.35) (4.06) (5.24) % given dignosis % referred on % told no problem / not to worry % problem recognized, but no ction (told to come bck if problem persists, etc) Other/not known At ech consulttion the Asperger group ws significntly older thn the utism group: 1st consulttion, t=7.73, P<0.001; 2nd consulttion, t=8.59, P<0.001, 3rd consulttion, t=7.76, P< Developmentl Medicine & Child Neurology 1999, 41:

4 obtin finl dignosis nd prentl stisfction (r=0.38, P<0.001). INITIAL SYMPTOMS OF CONCERN TO PARENTS Prents were sked to list, in order of priority, the behviours tht first gve them prticulr cuse for concern. In the utism group, by fr the most common re of difficulty cited ws dely (or some other bnormlity) in lnguge development, with lmost 44% of fmilies identifying this s their prime source of nxiety. Abnorml socil development ws the second mjor cuse of worry nd generl behviour problems the third (see Tble III). Ritulistic or stereotyped behviours did not rise prticulr nxieties t this stge, presumbly becuse the children were so young. The order of the concerns cited by prents in the Asperger group ws very similr lthough reltively fewer hd been worried bout their child s erly lnguge development (χ 2 =6.35; P<0.05). Generl behviour problems, including toileting nd eting difficulties, tntrums, nd so on were more frequently cited in the Asperger group thn in the utism group, lthough there were no significnt group differences on this or the other mesures. RELATIVE PROPORTIONS OF CASES WITH AUTISM AND ASPERGER DIAGNOSES Although the overll proportion of utism to Asperger dignoses ws pproximtely 4:1, the rtio vried ccording to ge (see Fig. 1). A dignosis of Asperger syndrome ws significntly more likely to be given to children ged over 10 yers thn it ws to those under 10 yers (χ 2 =40.21; P<0.001). Only few children (16) ged under 5 hd been given dignosis of Asperger syndrome. In the group ged under 10 yers the rtio of utism to Asperger dignoses ws 7.7:1; in the group ged over 10 yers there ws slight excess of children dignosed with Asperger syndrome (1.2 Asperger: 1.0 utism). GEOGRAPHICAL VARIATION IN THE DIAGNOSIS OF AUTISM AND ASPERGER SYNDROME For the purposes of this nlysis, the UK ws divided into 10 seprte res. This division is, of necessity, somewht crude, Tble III: First problems to concern prents Problem re Autism group Asperger group (N=614) (N=156) Lnguge development 43.6% 25.6% Socil development nd ply 19.0% 24.3% Generl behviour problems 12.5% 22.4% (including feeding difficulties) Motor nd other developmentl 8.8% 5.7% delys (including toileting) Medicl problems (including 7.6% 6.4% hering difficulties) Routines nd rituls 3.4% 6.4% Other (including concerns 2.4% 3.8% bout schooling) No worries until professionls 2.3% 5.1% expressed concern Not known 0.2% 0% % of prents citing s first concern. Tble IV: Reltive proportions of utism nd Asperger dignoses in different res Are (N of cses) Autism group Asperger group (N=598) % (N=155) % London nd South Est (238) West/South West (62) Midlnds (106) Est (46) North West (81) North, North-centrl nd Est (107) Wles (30) Scotlnd (57) Informtion missing on 16 children in the utism group nd one child in the Asperger group; the 26 children who were dignosed outside the UK re lso excluded from this tble. % <2 to <5 to <10 to <15 to 15 ³ Age group (y) Figure 1: Reltive proportions of Asperger nd utism dignoses t different ge. children with utism, children with Asperger syndrome. Dignosis of Autism nd Asperger Syndrome Ptrici Howlin nd Ann Asghrin 837

5 but brekdown into smller regions would hve resulted in the number of respondents in ech being very smll. The geogrphicl distribution of the smple is summrized in Tble IV. Although the frequency of cses dignosed s hving utism or Asperger syndrome vried from one region to nother, the reltive proportions of the two conditions did not vry significntly from the expected proportion of 4:1, i.e. overll rtio of children with utism to children with Asperger syndrome. Discussion The results of this survey, bsed on replies from over 700 fmilies, provide the nswers to number of questions bout the dignosis of Asperger syndrome nd utism. It is cler tht the former lbel is much less likely to be used for children who re dignosed under 10 yers of ge, nd is very rrely given to children below 5 yers of ge. The dignosis is given less frequently to femles thn to mles, probbly becuse some femles with utistic spectrum disorders re more likely to be of low IQ (Volkmr et l. 1993). In ddition, some regionl vrition occurs in the use of the Asperger lbel cross the country, lthough this is generlly no greter thn would be expected by chnce. Other findings pertining to the dignosis re supported by previous ccounts of erly symptomtology in utism (Frith et l. 1993, Smith et l. 1994, De Gicomo nd Fombonne 1998). Thus, prents re usully well wre of problems relted to their child s development by the second yer of life. Despite this, mny fmilies hve to wit for months (sometimes yers) before they obtin dignosis. The men figures for ge of dignosis lso tend to disguise the fct tht in both groups number of individuls (13 in the utism group nd 15 in the Asperger group) were not dignosed until they were over 20 yers of ge. Indeed, one individul with utism ws dignosed t the ge of 41 yers. Moreover, despite the fct tht ritulistic nd stereotyped behviours re mong the core dignostic symptoms of utism, only few prents (3% in the utism group nd 6% in the Asperger group) initilly cited these s their principl worries. Insted, erly concerns generlly focused round communiction, socil, nd behviour problems. Thus, even if stereotyped or ritulistic behviours re not reported by prents, clinicins should be wre tht children with erly delys in socil nd communiction skills my be t risk of hving n utistic spectrum disorder. Probbly the most importnt finding to emerge from this survey is tht, s predicted, prents of children with Asperger syndrome experience more frustrtion nd greter delys in their serch for dignosis thn do those with child with utism. Of prticulr clinicl relevnce ws the finding tht on verge children with utism were being dignosed t round 5 yers of ge wheres those with Asperger syndrome tended to be dignosed much lter, t over 11 yers of ge. Prents of children with Asperger syndrome were lso much more likely to be incorrectly ressured tht their child would grow out of his or her problems, or tht there ws nothing to worry bout. It is cler tht lthough improvements cn be mde in the dignosis of children with utism spectrum disorders more generlly (Howlin nd Moore 1997) the sitution is prticulrly worrying for prents of child with Asperger syndrome. Mny such children re neither identified nor provided with ny support until they hve completed the crucil yers in primry school. One issue tht remins unresolved is the reltive frequency of children with Asperger syndrome compred with those with utism. While figures from Sweden (Ehlers nd Gillberg 1993) suggest tht the prevlence of Asperger syndrome my be lmost twice tht of other utistic spectrum disorders, in the present study dignosis of utism ws much more common thn one of Asperger syndrome (pproximtely 4:1). A similr rtio (4.2:1) is reported in the smller scle study by Vostnis et l. (1998) in the UK. However, s the proportions pper to differ ccording to the specific ge group studied, more reserch in this re is required. As with ny postl survey, the findings need to be treted with cution. Firstly the rte of returns, lthough impossible to estimte exctly, ws fr from 100%, nd there is no wy of scertining whether the experience of responders ws the sme s for non-responders. Moreover, relince on retrospective reports is lso prone to errors. Nevertheless, mny of the findings re supported by other, smller scle studies of erly dignosis. Thus, s noted bove, reports by Frith et l. (1993), Smith et l. (1994), nd De Gicomo nd Fombonne (1998) ll indicte tht for utism disorders generlly, prents first become wre of their child s difficulties round 18 to 19 months of ge. In ddition, the types of problems first noted by prents tend to be similr cross studies, with delys in communiction nd socil responsiveness (but not necessrily the presence of ritulistic nd stereotyped behviours) being the initil symptoms to cuse concern (cf. Osterling nd Dwson 1994, Smith et l. 1994, De Gicomo nd Fombonne 1998). An dditionl problem with the present study is tht it ws not possible to check the ccurcy of the dignostic lbels reported by prents, nor to determine how these were derived. Given disgreement in the literture over the definition of Asperger syndrome, there cn be no certinty tht this dignosis, in prticulr, ws consistently bsed on the sme criteri. Nevertheless, the Asperger lbel is generlly used to refer to higher functioning individuls within the utistic spectrum (Wing 1996). Thus, it my be ssumed tht prents of children with less severe cognitive nd linguistic impirments re likely to fce more delys nd difficulties in obtining dignosis. Such delys my hve prcticl, psychitric, nd even genetic implictions. Firstly, it is well estblished tht erly interventions for children with developmentl disbilities cn be importnt in incresing cognitive, linguistic, socil, nd self-help skills (Rogers 1996, Dwson nd Osterling 1997). Assisting prents to develop effective mngement techniques is lso likely to void or minimize the emergence of secondry behviourl problems (Howlin nd Rutter 1987, Lovs 1993, Howlin 1998). The longer dignosis is delyed, the longer children will hve to wit before they re provided with suitble eduction, or their prents offered pproprite help nd support. Secondly, s more ble children within the utistic spectrum re likely to be educted in minstrem school, delyed recognition of their problems cn result in exposure to ineffective or inpproprite teching methods tht fil to tke ccount of their problems of communiction nd understnding. Eductionl filure cn result in depression nd low self-esteem, rejection by peers, nd often hrsh tretment 838 Developmentl Medicine & Child Neurology 1999, 41:

6 from techers (Howlin 1988). It is hrdly surprising, therefore, tht this group tends to be prticulrly prone to psychitric nd emotionl difficulties in dulthood (Tntm 1991). Thirdly, delys in dignosis my hve wider implictions for fmilies. It is now ccepted tht utism is probbly mong the most heritble of ll childhood disorders (Biley et l. 1996). For ny fmily with child with utism or Asperger syndrome, there is significnt risk tht other children in the fmily my hve socil, linguistic, or other cognitive problems. If recognition of the child with utism or Asperger syndrome is delyed, then siblings with the broder phenotype re even more likely to be overlooked, nd thus deprived of the help they my need to minimize their problems. Accepted for publiction 19th July References Americn Psychitric Assocition. (1994) Dignostic nd Sttisticl Mnul of Mentl Disorders, 4th edition. (DSM-IV). Wshington, DC: Americn Psychitric Assocition. Biley A, Phillips W, Rutter M. 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