Cognitive screening for long term substance use outcome in a cohort of patients with polysubstance use disorder

Background: Cognitive impairments among patients with substance use disorders (SUD) are frequent and associated with adverse treatment outcomes such as relapse and drop out. However, Long-term outcome-trajectories of patients with cognitive impairments, is largely unknown. The aim of the current study was to determine whether results from common clinical screening instruments for cognitive impairment could predict one and five year substance use outcome in a cohort of patients with poly substance use disorder after entering treatment as usual.

Methods: We applied a cross-sectional analytical design to data from the Stavanger Study of Trajectories of Addiction (STAYER, n = 164), a cohort study of patients with a SUD from the Stavanger University hospital catchment area. We used the Wechsler Abbreviated Scale of Intelligence, Montreal Cognitive Assessment and Behavior Rating Inventory of Executive Function - Adult version to assess cognitive impairments according to recommended cut-off values. We assessed substance use with the Drug Use Disorders Identification Test Consumption items (DUDIT-C) and defined substance abstinence (DUDIT-C =0) and heavy substance use (DUDIT-C > 6) categories.

Results: At year one, 54% of the total sample reported total abstinence from substances. Conversely, 31% presented heavy substance use. At year five, 64% of the total sample reported abstinence from substances while 25% presented heavy substance use. There were no differences in substance abstinence or heavy substance use between patients with and without cognitive impaired at one and five year measurements.

Conclusion The predictive value of cognitive impairments to predict long term substance use outcome may be weak. Accordingly, results from cognitive screening at treatment initiation should be interpreted with caution. There is a need to establish clinically viable instruments to assess cognitive functions with well-established clinical and ecological validity in the SUD population.