Frontal systems deficits in stimulant-dependent patients: Evidence of pre-illness dysfunction and relationship to treatment response.

Frontal systems dysfunction is present in stimulant-dependent patients. However, it is unclear whether this dysfunction is a pre-morbid risk factor or stimulant-induced, is severe enough to be clinically relevant, and if it is relevant to treatment response. These questions were addressed using the Frontal Systems Behavior Scale (FrSBe), a reliable and valid self-report assessment of three neurobehavioral domains associated with frontal systems functioning (Apathy, Disinhibition, and Executive Dysfunction, summed for a Total), that assesses both pre- and post-morbid functioning, and has a specific cutoff for defining clinically significant abnormalities. In this ancillary investigation (protocol CTN-0031-A-1, “An Evaluation of Neurocognitive Function, Oxidative Damage, and Their Association with Treatment Outcomes in Methamphetamine and Cocaine Abusers”), six sites evaluating 12-step facilitation for stimulant abusers obtained the FrSBe from 180 methamphetamine- and/or cocaine-dependent participants. Dichotomous treatment response measures included self-reported stimulant use, stimulant urine drug screens, and treatment completion. A substantial percentage of participants retrospectively reported clinically significant neuro-behavioral abnormalities prior to lifetime stimulant abuse initiation (e.g., 67.5% on FrSBe-Total), with a significant increase in the proportion reporting such abnormalities for current functioning (86% on the FrSBe-Total; p<0.0001). Treatment response was significantly worse for participants with, relative to those without, clinically significant Disinhibition as measured by treatment non-completion (31.6% vs. 15.6%) and self-reported stimulant use during treatment (40.5% vs. 16.7%).

Conclusions: The present study revealed that stimulant-dependent patients evidence frontal systems dysfunction as measured by the FrSBe, that frontal systems dysfunction was present prior to the initiation of stimulant abuse based on retrospective ratings, that stimulant use was associated with significant worsening of frontal systems function, and that clinically significant Disinhibition was associated with poorer treatment response. The study results suggest that the FrSBe may have utility in evaluating the role of frontal systems dysfunction in stimulant-dependence, and that disinhibition may be a prime target for intervention in stimulant-dependent individuals. Future research to replicate, and expand on, the present findings seems warranted.

Related protocols: CTN-0031-A-1