Impaired Learning From Negative Feedback in Stimulant Use Disorder: Dopaminergic Modulation.

BACKGROUND: Drug-induced alterations to the dopamine system in stimulant use disorder (SUD) are hypothesized to impair reinforcement learning (RL). Computational modeling enables the investigation of the latent processes of RL in SUD patients, which could elucidate the nature of their impairments. METHODS: We investigated RL in 44 SUD patients and 41 healthy control participants using a probabilistic RL task that assesses learning from reward and punishment separately. In an independent sample, we determined the modulatory role of dopamine in RL following a single dose of the dopamine D2/3 receptor antagonist amisulpride (400 mg) and the agonist pramipexole (0.5 mg) in a randomised, double-blind, placebo-controlled, crossover design. We analyzed task performance using computational modelling and hypothesized that RL impairments in SUD patients would be differentially modulated by a dopamine D2/3 receptor antagonist and agonist. RESULTS: Computational analyses in both samples revealed significantly reduced learning rates from punishment in SUD patients compared with healthy controls, whilst their reward learning rates were not measurably impaired. In addition, the dopaminergic receptor agents modulated RL parameters differentially in both groups. Both amisulpride and pramipexole impaired RL parameters in healthy participants, but ameliorated learning from punishment in SUD patients. CONCLUSION: Our findings suggest that RL impairments seen in SUD patients are associated with altered dopamine function.

Reduced Glutamate Turnover in the Putamen Is Linked With Automatic Habits in Human Cocaine Addiction.

BACKGROUND: The balance between goal-directed behavior and habits has been hypothesized to be biased toward the latter in individuals with cocaine use disorder (CUD), suggesting possible neurochemical changes in the putamen, which may contribute to their compulsive behavior. METHODS: We assessed habitual behavior in 48 patients with CUD and 42 healthy control participants using a contingency degradation paradigm and the Creature of Habit Scale. In a subgroup of this sample (CUD: n = 21; control participants: n = 22), we also measured glutamate and glutamine concentrations in the left putamen using ultra-high-field (7T) magnetic resonance spectroscopy. We hypothesized that increased habitual tendencies in patients with CUD would be associated with abnormal glutamatergic metabolites in the putamen. RESULTS: Compared with their non-drug-using peers, patients with CUD exhibited greater habitual tendencies during contingency degradation, which correlated with increased levels of self-reported daily habits. We further identified a significant reduction in glutamate concentration and glutamate turnover (glutamate-to-glutamine ratio) in the putamen in patients with CUD, which was significantly related to the level of self-reported daily habits. CONCLUSIONS: Patients with CUD exhibit enhanced habitual behavior, as assessed both by questionnaire and by a laboratory paradigm of contingency degradation. This automatic habitual tendency is related to a reduced glutamate turnover in the putamen, suggesting a dysregulation of habits caused by chronic cocaine use.

Impulsivity and compulsivity are differentially associated with automaticity and routine on the Creature of Habit Scale.

Habits may develop when meaningful action patterns are frequently repeated in a stable environment. We measured the differing tendencies of people to form habits in a population sample of n = 533 using the Creature of Habit Scale (COHS). We confirmed the high reliability of the two latent factors measured by the COHS, automaticity and routines. Whilst automatic behaviours are triggered by context and do not serve a particular purpose or goal, routines often have purpose, and because they have been performed so often in a given context, they become automatic only after their action sequence has been activated. We found that both types of habitual behaviours are influenced by the frequency of their occurrence and they are differentially influenced by personality traits. Compulsive personality is associated with an increase in both aspects of habitual tendency, whereas impulsivity is linked with increased automaticity, but reduced routine behaviours. Our findings provide further evidence that the COHS is a useful tool for understanding habitual tendencies in the general population and may inform the development of therapeutic strategies that capitalise on functional habits and help to treat dysfunctional ones.

Creature of Habit: A self-report measure of habitual routines and automatic tendencies in everyday life.

Our daily lives involve high levels of repetition of activities within similar contexts. We buy the same foods from the same grocery store, cook with the same spices, and typically sit at the same place at the dinner table. However, when questioned about these routine activities, most of us barely remember the details of our actions. Habits are automatically triggered behaviours in which we engage without conscious awareness or deliberate control. Although habits help us to operate efficiently, breaking them requires great effort. We have developed a 27-item questionnaire to measure individual differences in habitual responding in everyday life. The Creature of Habit Scale (COHS) incorporates two aspects of the general concept of habits, namely routine behaviour and automatic responses. Both aspects of habitual behaviour were weakly correlated with underlying anxiety levels, but showed a more substantial difference in relation to goal-oriented motivation. We also observed that experiences of adversity during childhood increased self-reported automaticity, and this effect was further amplified in participants who also reported exposure to stimulant drugs. The COHS is a valid and reliable self-report measure of habits, which may prove useful in a number of contexts where discerning individuals' propensity for habit is beneficial.