Cognitive and behavioural dispositions in offspring at high risk for alcoholism

Brain networks underlying vulnerability and resilience to drug addiction

Resting-state functional connectivity provides novel insight into variations in neural networks associated with addiction to stimulant drugs in individuals with and without a family history of addiction, and both with and without personal drug use. An increased risk for addiction, either because of drug use or genetic/psychosocial vulnerability, is associated with hypoconnectivity in frontostriatal networks, which may weaken goal-directed decision-making. Resilience against addiction development, by contrast, is characterized by hyperconnectivity in two corticostriatal pathways, possibly reflecting compensatory responses in networks associated with regulatory control over habitual behaviors. It is thus conceivable that defying the risk of developing stimulant drug addiction requires increased efforts to control behavior—a hypothesis that may open up new pathways for therapeutic and preventative strategies.

Regular drug use can lead to addiction, but not everyone who takes drugs makes this transition. How exactly drugs of abuse interact with individual vulnerability is not fully understood, nor is it clear how individuals defy the risks associated with drugs or addiction vulnerability. We used resting-state functional MRI (fMRI) in 162 participants to characterize risk- and resilience-related changes in corticostriatal functional circuits in individuals exposed to stimulant drugs both with and without clinically diagnosed drug addiction, siblings of addicted individuals, and control volunteers. The likelihood of developing addiction, whether due to familial vulnerability or drug use, was associated with significant hypoconnectivity in orbitofrontal and ventromedial prefrontal cortical-striatal circuits—pathways critically implicated in goal-directed decision-making. By contrast, resilience against a diagnosis of substance use disorder was associated with hyperconnectivity in two networks involving 1) the lateral prefrontal cortex and medial caudate nucleus and 2) the supplementary motor area, superior medial frontal cortex, and putamen—brain circuits respectively implicated in top-down inhibitory control and the regulation of habits. These findings point toward a predisposing vulnerability in the causation of addiction, related to impaired goal-directed actions, as well as countervailing resilience systems implicated in behavioral regulation, and may inform novel strategies for therapeutic and preventative interventions.

Underlying decision making processes on Iowa Gambling Task

BACKGROUND

Iowa Gambling Task (IGT) assesses decision making in uncertain conditions. Several studies have reported impaired performance on IGT in various clinical population compared to healthy normal. However, some researchers have reported incongruent findings from the basic assumptions of IGT in healthy normal. Our aim was to examine the possible decision making processes on IGT.

METHODS

The IGT was administered on two groups: Healthy normal (n = 34) and offspring at high risk for alcoholism (n = 34). Subjects were matched on age (+/-1 year), education (+/-1 year) and gender. Other tools used were: Mini-international Neuropsychiatric Interview, Family Interview for Genetic Studies, Socio-demographic Data Sheet, Annett's Handedness Questionnaire.

RESULTS

Results showed a significant difference between two groups on selections made from disadvantageous deck A but no significant difference on disadvantageous deck B, advantageous/safe decks C and D. Also, there was no significant difference between two groups on IGT Net score [selections from decks (C + D) - decks (A + B)]. Further analysis showed that varying nature of reward and penalty schedules play an important role in selecting the cards from four decks of IGT. Subjects may prefer infrequent penalty decks without consideration of delayed loss/gain.

CONCLUSION

Frequency and magnitude of reward/penalty in IGT may adversely impact decision making. Deck B can induce myopia for delayed loss in the healthy normal too because of having a high frequency of gains with high magnitude of reward. Hence, IGT related studies should consider these factors while making an inference about decision making ability.