Subjects at Ultra High Risk for psychosis have 'heterogeneous' intellectual functioning profile: a multiple-case study.

In Ultra High Risk (UHR) studies, intellectual functioning is commonly assessed using premorbid IQ tools as a covariate. The aim of this study was to show that the use of the Wechsler Adult Intelligence Scale (WAIS) could yield accurate neuropsychological profiling and that an alternative approach such as a multiple-case study could be a more interesting way to isolate discrete cognitive processes in the early stage of illness. The studied population consisted of 198 adolescents and young adults (16-30 y.o.) referred to our outpatient clinic. After the CAARMS' interview, we defined 3 subgroups: UHR (N=104), First Episode (FE; N=30), and Help-Seekers (HS; N=64) who were neither UHR nor psychotic. Intellectual functioning was assessed by the WAIS-III (9 subtests version) and 'heterogeneous' intellectual profiles were defined based on the existence of a 3-point difference in scoring at subtests constitutive of the same WAIS index. While UHR did not differ from FE or HS on WAIS' scores and sub-scores, the multiple-case study indicated a higher proportion of 'heterogeneous' profiles in the Verbal Comprehension Index in the UHR sample than in FE and HS (p=0.04). The disease progression could heterogeneously impact on specific domains, in patterns depending on the stage of the illness. This approach exploring intra-subject WAIS performances might be more relevant than the use of global scores in detecting the subtle cognitive alteration of emerging psychosis.