Assessment of neurocognitive disorder in studies of cognitive impairment due to substance use disorder: A systematic review

Background: Cognitive impairments induced by substance use disorders (SUDs) are broadly documented. Evidence for these effects ought to be considered with regard to the new classification of neurocognitive disorders (NCDs). Failing to assess diagnostic criteria for NCD could be a limitation of studies addressing the effects of SUDs on cognition, resulting in misdiagnosis and inaccurate prevalence estimation. Methods: A systematic search of original articles (2000–2016) was conducted in Web of Knowledge and Science Direct. Key terms were: NCD and associated terms, and SUDs or alcohol, marijuana, cocaine and inhalants. Results: 59 cross-sectional and five prospective studies were reviewed. Criterion A.1 (evaluation of subjective concern of cognitive decline relative to a baseline), and criterion B (evaluation of impairment in daily life activities due to cognitive impairment) were not effectively evaluated in any of the studies. All studies addressed criterion A.2 (objective evidence of cognitive decline) via heterogeneous neuropsychological testing. Criteria C (absence of delirium) and D (absence of other possible etiologies) were frequently considered for control of confounding effects, mostly via methodological procedures (e.g. abstinence before evaluation, and exclusion of participants with comorbid disorders). Conclusion: These findings highlight the need to develop and disseminate standard procedures for assessment of substance-induced NCD.