Asperger Syndrome Diagnostic Scale (“ASDS”) Brenda Smith Myles, Stacey Jones Bock, Richard L. Simpson (2001) Diana Kelly, PS 616 (9/08)
Brief History of Asperger’s Syndrome • Leo Kanner delineates the diagnostic criteria for Autism (aka “Kanner’s Syndrome”). • 1943: Kanner identifies a group of autistic children, apparently “normal”, but who are naïve, lack appropriate speech pragmatics and prosody, lack empathy, and have poor non-verbal communication. (Ozonoff, et al., 2005; Freeman et al., 2002)
History cont. • In 1944, Hans Asperger describes a similar group of autistic boys, but notes no speech delay, the presence of motor clumsiness, and a late onset of social deficits. (Ozonoff et al., 2005; Freeman et. al, 2002)
History cont. • Wolff & Barlow, in 1979, describe a similar group of children diagnosed with schizoid personality disorder – characteristics considered to be stable personality traits. • In 1981, Wing translates Asperger’s paper into English and demonstrates the connection to Kanner’s 1943 group. (Ozonoff et al., 2005: Freeman et al., 2002).
History cont. • In 1989, Rourke describes yet another group of children who have been identified as having NVLD neuropsychological profiles – essentially autistic-like deficits but with well-developed “rote” verbal repertoires. (Ozonoff et al., 2005; Freeman et al., 2002)
AS Included In DSM-IV • By 1994, enough varying views of AS resulted in the consensus that AS should be included in the DSM-IV under the category of PDD. (Ozonoff et al., 2005; Freeman et al., 2002)
Current Debate In AS Assessment • How to assess AS vs. other PDDs? • What characteristics overlap? • Are the characteristics inimical only to AS to permit differential diagnosis, and, if so, what are they and how to measure them? • When are these characteristics capable of accurate measurement?
DSM-IV-TR Criteria for AS • Same qualitative social impairment, restrictive and stereotypic behavior patterns and impairment in social, occupational or important area of functioning. • Except . . .
DSM-IV-TR- AS Qualifiers • No clinically significant delay in the onset of: • Language (single words at 2; communicative phrases -3); • Age-appropriate self-help skills, adaptive behavior (other than social), and environmental curiosity. • Criteria not met for another PDD or Schizophrenia. (DSM-IV: American Psychiatric Association, 1994; DSM-IV-TR, American Psychiatric Association, 2000).
The ASDS • Developed in 2001. • 50 item test, rated as observed (1) or not observed (0). • Rater needs to be an “appropriate person” with regular, sustained contact with examinee for at least 2 weeks, (e.g., parent, teacher). • Examiner is person scoring and interpreting the ASDS results.
ASDS cont. • Appropriate for ages 5-18 • Completion time 10-15 minutes • Scale normed on 115 individuals from 21 states in the U.S. • Provides standard scores and percentile ranks
Reliability From Manual • Cronbach’s (1951) coefficient alpha used to determine internal consistency of the instrument and subscales. • Higher consistency on ASDS as a whole to suggest AS, but less reliable on the subscales individually, thus recommends subscales be used only to determine relative individual strengths and weaknesses, not to identify AS
Interrater Reliability • 14 AS subjects (mean age 12) rated by teachers & parents. • The resulting correlation coefficient for the ASQ calculated was .93 – considered strong, statistically significant, and indicative that ratings will be similar across different raters with the same subject.
Validity From Manual • Evidence was provided for three types of validity: • Content • Criterion • Construct (Interestingly, there is no discussion of external validity).
Content Validity • Item Analysis: • Items on ASDS derived from the DSM-IV, the ICD-10; AS literature on ERIC and PsychInfo databases (1975-1999), and Asperger’s 1944 research. 6 resulting categories combines into 5.
Item Discrimination • An item analysis was not done at separate age levels since research indicate that there is not relationship between age and ASDS scores. • Item discrimination was tested by the Pearson item-total-score correlation index, yielding statistical significance, and coefficients indicating items well-exceeded minimum criteria for magnitude.
Criterion Validity • ASDS ability to differentiate amongst different diagnostic groups. • 2 groups: 115 diagnosed with AS; normative group of 177 with autism, behavior disorders, ADHD, LD. • Discriminant analysis showed a statistically significant difference between the mean ASQ for the AS and non-AS samples; accuracy of 85% correct classification.
Construct Validity-Hypotheses • AS characteristics not correlated with age, so ASQ should not be related to age. • ASDS item characterize AS and should correlate with total test score • As ASDS measure AS characteristics, it should not correlate strongly with scale for autism • ASDS measures AS characteristics and should differentiate between AS and non-AS groups.
ASDS Evaluation of ASQ – Age • Little published research by 1999-2001. • Correlated ASDS raw scores between sample groups, ages 5-18. Coefficient of .14 confirms no practical relation.
Discriminant Validity • Correlated ASDS scores with GARS scores. • GARS targets autism and ASDS targets AS. • Correlational coefficient was not significant, magnitude reported as moderate. • Thus, conclusions that ASDS and GARS measure different conditions.
Group Differentiation • Expectation that each groups results should make sense: that individuals not having AS would have ASQ and subscale scores significantly different than those having AS • Mean subscale and quotient standard scores were significantly higher for those with AS.
The Test Itself • The 50 items are divided into 5 subscales: • Language: Receptive & Expressive (9) • Social: reciprocity, eye contact, gestures, perspective (13) • Maladaptive: Obsessions, rituals, routine change, behavioral control, anxiety (11) • Cognitive: rote & visual memory, intelligence, related cognitive issues (10) • Sensorimotor: auditory, tactile, olfactory, gustatory sensitivities; fine & gross motor
ASDS Instructions • Examiner’s manual includes: • Specific administration & scoring procedures: computing & converting raw scores, standard scores, percentile ranks, and the resultant Asperger Syndrome Quotient (ASQ).
Scoring • Total raw scores converted by table into %ile and ASQ. (ASQ has a mean of 100 and standard deviation of 15, compares this individual with others with AS.) • Raw score for each subscale converted in %ile rank and standards scores. (Mean of 10, standard deviation of 3).
Profile • Profile of Scores: scatter plot graphic plotting of subscale standard scores and ASQ. • Provides visual assessment of likelihood of AS and the areas of strength and weakness. • Higher scores = greater probability of AS.
Examiner’s Manual Cautions • The ASDS results may be indicative of AS, but does not diagnose AS as all testing has error and confounds to be considered • Advises comprehensive evaluation for diagnosis • Suggests that ASDS has utility in aiding diagnosis & in treatment planning or modification
ASDS Written Report • Form includes a brief written report: • Description of specific symptoms observed, • Functional impact on subject, • Implications and recommendations re: work, leisure, instruction • Recommendations for strategies and interventions regarding instruction, behavior, parenting, and related services
Early Development Interview • In addition, the ASDS includes 10 key questions (also in the questionnaire) to flesh out additional information on the onset of symptoms, relative severity, relativity across settings.
Reasons To Use ASDS • The ASDS is easy to administer • Takes little time, 10-15 minutes • Easy to score and scale and read • Allows for additional information on an individual subject’s idiosyncrasies that is useful in treatment planning.
Relevant Research on ASDS • Only one review could be located giving strong support for the ASDS as a tool to differentiate AS from autism. (Mirenda, P., 2003).
Limitations cont. • The most significant limitation of the ASDS is the lack of agreed upon operational differential diagnostic components to distinguish AS from or as a variant of autism, HFA, and PDD-NOS. (Toth & King, 2008; Boggs et al., 2006; Campbell, J.M., 2005; McConachcie et al., 2005; Ozonoff et al., 2005; Freeman et al., 2002; Blair, K. A. (2003).
GARS measures autism. • GADS and the KADI, the only other AS specific tests also have same weaknesses as ASDS with respect to diagnoses verification. • KADI has strong psychometrics, ASDS the weakest. KADI also has age groups. (Campbell, J.M., 2005; McConachie et al., 2005; Ozonoff et al., 2005; Blair, K., 2003).
Some studies note that most if not all symptoms seen in autism are seen in AS; other recent studies suggest that AS and autism appear different at young age, that by adolescence the differences are less apparent, and individuals appear less distinct. Perhaps the “course” should be included in screening. (Boggs et al., 2006); McConachie et al., 2005; Ozonoff et al., 2005; Freeman et al., 2002).
The debate also suggests that to determine the presence of AS: • evaluate the type and use of language & skills that appear, not simply their age of onset; • presence of hyperactivity, depression, motor clumsiness • the “course” of repetitive behaviors (Boggs wt al., 2006; (Ozonoff et al., 2005; McConachie, et al., 2005).
ASDS Compared To Other Tools • There are no published comparison studies that would use the ASDS alone or rank it as superior to other AS-specific screening tools. • One study found that KADI to be the most thorough; one preferred the ASSQ (but could not recommend any scale); one found a combination of the ASDS, GARS and SSRS to be most reliable. (Boggs et al., 2006; Ozonoff et al., 2005; Campbell, J.M., 2005).
References • Blair, K. A. (2003) Test review of the Asperger Syndrome Diagnostic Scale. From Plake, B. S., Impara J.. C., & Spies, R.A. (Eds), The fifteenth mental measurements yearbook, [Electronic version]. Retrieved 9/15/2008, from the Buros Institute’s Test reviews Online website: http://www.unl.edu/buros. • Boggs, K. M., Gross, A. M., & Gohm, C. L. (2006). Validity of the Asperger Syndrome Diagnostic Scale. Journal of Developmental and Physical Disabilities, 18:2, 163-182. • Campbell, J. M. (2005). Diagnostic assessment of Asperger’s disorder: A review of five third-party rating scales. Journal of Autism and developmental Disorders, 35:1, 25- 35.
References cont. • Freeman, B. J., Cronin, P.,& Candela, P. (2002). Asperger syndrome or autistic disorder? The diagnostic dilemma. Focus On Autism and Other Developmental Disabilities, 17:3, 145-151. • Goldstein, S. (2002). Review of the Asperger Syndrome Diagnostic Scale. Journal of Autism and Developmental Disorders, 32:6, 611-614. • McConachie, H., Couteur, A. L.,& Honey, E. (2005). Can a diagnosis of Asperger syndrome be made in very young children with suspected autism spectrum disorder? Journal of Autism and Developmental Disorders, 35:2, 167-176.
References cont. • Mirenda, P. (2003) Test review of the Asperger Syndrome Diagnostic Scale. From Plake, B. S., Impara J.. C., & Spies, R.A. (Eds), The fifteenth mental measurements yearbook, [Electronic version]. Retrieved 9/15/2008, from the Buros Institute’s Test reviews Online website: http://www.unl.edu/buros. • Myles, B.S., Bock, S. J., & Simpson, R. L. (2001). Asperger Syndrome Diagnostic Scale (ASDS), PRO-ED, Austin, TX. • Ozonoff, S., Goodlin-Jones, B. L., & Solomon, M. (2005). Evidence-based assessment of autism spectrum disorders in children and adolescents. Journal of Clinical Child and Adolescent Psychology, 34:3, 523-540. • Toth, K., & King, B.H., (2008). Asperger’s syndrome: diagnosis and treatment. The American Journal of Psychiatry, 165:8, 958-963.