IQ in Autism: Is there an Alternative Global Cognitive Index?

BACKGROUND: Intelligence quotient (IQ) but not the core symptoms have been known to predict outcomes in autism. Besides resource issues in India, assessing IQ in presence of autistic symptoms is challenging in general. MATERIALS AND METHODS: In a pilot study, we explored different global indices of development in 30 children with confirmed autism. These included Wechsler intelligence scale for children or Wechsler preprimary scale of intelligence-revised (n = 10), Raven's progressive matrices (RPM) (n = 10), Vineland adaptive behavior scales II, parent report version (VABS) (n = 30) and teacher's estimate of mental age (TIQ) (n = 30). Three subgroups (Group A) with Wechsler's scales derived IQ (WISIQ), (Group B) with RPM derived IQ and (Group C) those without a formal IQ measure were compared. RESULTS: All groups were comparable on age and their scores on Childhood Autism Rating Scale and Indian Scale for Assessment of Autism Adaptive behavior composite scores (Ad Bh composite) derived from VABS and WISIQ showed significant correlations with each other in Group A; TIQ significantly correlated with Ad Bh composite scores, but not with the WISIQ, although the latter two scores themselves did not significantly differ from each other. RPM consistently overestimated children's performance compared to Ad Bh composite or TIQ in Group B, but the Ad Bh composite and TIQ were themselves significantly correlated. In Group C, there were poor correlations between Ad Bh composite and TIQ. The Ad Bh composite score in this group was significantly different from the other two groups. CONCLUSION: There is a need to fine tune the assessment for global cognitive measures in autism and explore their real world importance.