Does the gambler's brain respond differently while awaiting a reward?
Abstinent problem gamblers showed weaker insula activity while anticipating a reward, and this weakening was greater the longer they had been ill.
Source
Insular activation during reward anticipation reflects duration of illness in abstinent pathological gamblers
Study at a glance
- Design
- Case-control — Cross-sectional fMRI comparison of abstinent, treatment-seeking male pathological gamblers and age-matched healthy men during a points-based incentive delay task, plus within-patient correlations with illness and abstinence duration
- N
- N=50 · 23 pathological gamblers (after excluding one with an unusually long abstinence) and 27 healthy controls; correlations use the 23 patients only
- Population
- Japanese adult men: abstinent pathological gamblers from a residential 12-step treatment facility and age-matched healthy men from the community
- Outcome
- BOLD activation in striatum, insula and midbrain during reward anticipation; correlation of activation with self-reported duration of illness and of abstinence
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What they did
Men diagnosed with pathological gambling who had stopped gambling and were in residential treatment, and healthy men of similar age, did a reaction-time game in an MRI scanner. Each trial began with a cue announcing how many points a fast response could win, so the researchers could measure brain activity while people waited for a possible reward. Points were used instead of real money so that the task would not act as a gambling cue for patients in recovery. The team compared the groups and, within the gamblers, related brain activity to how long they had been ill and how long they had been abstinent.
What they found
Both groups activated reward-related areas while anticipating a reward, and the groups did not differ in the striatum or midbrain. The gamblers, however, showed weaker activation of the insula on both sides of the brain. In the gamblers, left insula activity fell as illness duration rose (a strong negative correlation, r = -0.654) and tended to rise with longer abstinence (r = 0.401), though the abstinence link just missed significance. Task performance did not differ between groups, and smoking severity did not explain the insula finding.
The limits
What it doesn't show
The design is cross-sectional, so it cannot show that gambling caused the insula change or that abstinence restores it; the authors note a longitudinal study is needed. The sample is small, all male, from one Japanese facility, and mostly machine (Pachinko) gamblers, which limits generalisation. Gamblers smoked more and a few had depression or ADHD, so these could not be fully ruled out as influences. Because points rather than money were used, the task produced no effect of reward size at all, and illness and abstinence durations were self-reported.
Key terms
- Pathological gambling
- A behavioural addiction in which a person keeps gambling despite serious harm; now grouped with substance use disorders in DSM-5 as gambling disorder.
- Monetary incentive delay task
- A reaction-time game where a cue signals how much can be won on a trial, letting researchers measure brain activity during reward anticipation separately from reward receipt.
- Insula
- A region of cortex folded deep inside the brain that integrates signals from the body and is linked to emotional and interoceptive arousal and to risk processing.
- Reward anticipation
- The period of expecting a possible reward before it arrives, which normally engages the striatum and related areas.
- Behavioural addiction
- An addiction to an activity rather than a drug, useful for studying addiction without the toxic effects of substances on the brain.
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Quiz yourself
Which region showed reduced activation in abstinent gamblers compared with controls?
Common questions
Why study gamblers rather than drug users to understand addiction?
Drugs can damage the brain directly, so changes in drug users might reflect toxicity rather than addiction itself. Gambling involves no substance, so brain differences are more likely to reflect the addictive behaviour.
Why did they use points instead of money?
Money could act as a gambling cue and trigger craving in patients trying to stay abstinent, which the treatment centre and ethics committee wanted to avoid. The trade-off is that points may be less motivating.
Does this show that stopping gambling heals the brain?
No. The abstinence correlation was only marginal and the data come from one time point in different people, so a study following the same patients over time would be needed.
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