Cognitive impairment as a predictor of long-term psychological distress in patients with polysubstance use disorders

Background: The association between polysubstance use disorder (pSUD), mental illness, and cognitive impairments is well established and linked to negative outcomes in substance use disorder treatment. However, it remains unclear whether cognitive impairment predicts long-term psychological distress among treatment seeking patients with pSUD. This study aimed to investigate the associations and predictive ability of cognitive impairment on psychological distress one and five years after treatment initiation.

Methods: N = 164 treatment seeking patients with pSUD were sampled at treatment initiation. We examined associations between cognitive impairment according to Montreal Cognitive Assessment® (MoCA®), Wechsler Abbreviated Scale of Intelligence (WASI), and Behaviour Rating Inventory of Executive Function - Adult version (BRIEF-A) administered at treatment initiation and psychological distress defined by the Symptom Check List-90-Revised (SCL-90-R) at treatment initiation and five years later. We ran hierarchical logistic regressions to assess the predictive ability of the respective cognitive instruments administered at treatment initiation on psychological distress measured five years later including psychological distress at treatment initiation and substance intake at the measurements as covariates.

Results: The main results was that MoCA®, WASI and BRIEF-A predicted psychological distress, but BRIEF-A lost predictive power when accounting for psychological distress at treatment initiation. 

Conclusions: MoCA® and WASI was found to be less sensitive to psychopathology-driven cognitive impairments than BRIEF-A. The explanatory power of cognitive impairment at treatment initiation on later psychological distress is limited