Background: We aimed to examine the predictive validity of the Weschler Adult Intelligence Scale (WAIS-IV) in predicting treatment completion, over and above educational status.
Methods: One hundred and ninety-six (N = 196) individuals from the Odyssey House Residential Rehabilitation Program, NSW, Australia between 2010 and 2016 were administered a structured interview including substance use disorders and the Verbal Comprehension (VCI), Perceptual Reasoning (PRI), Working Memory (WMI), and Processing Speed (PSI) domains of the WAIS-IV.
Results: There were significant differences between our clinical sample and the population norm with respect to the proportion below the mean for PSI (z = 12.27, p < .001), VCI (z = 2.33, p < .02) but not for WMI (z = 1.67, p < .10) or PRI (z = -1.76, p < .08). The WAIS-IV subscales did not significantly predict treatment completion (p's > .16) over and above educational status (p < .01).
Conclusions: Our findings suggest that in clients in drug and alcohol rehabilitation settings a combination of skills may be impacted including Verbal Comprehension and Processing Speed. Moreover, our findings also suggest that WAIS-IV subscales do not predict treatment completion in a drug and alcohol residential setting, over and above a brief assessment of educational status.
Keywords: Cognitive functioning; WAIS; rehabilitation; substance use; treatment.