Table 2.

Similarities and differences between pathological gambling (PG) and substance use disorders (SUDs) with regard to brain function research findings related to impulsivity and compulsivity (see text for details)

Brain region/structure	PG results	SUD: similarities/differences with PG
Frontal cortical regions	Response impulsivity tasks: PG/problem gamblers demonstrate less activity than do controls.	SUD/substance users also demonstrate less activity than controls.
	Compulsivity tasks: PG/problem gamblers demonstrate less activity than do controls. Lesion studies suggest vmPFC and dlPFC are important for task performance.	Smokers also demonstrate less activity than do controls.
	Risk/reward tasks: PG/problem gamblers demonstrate less activity than do controls. In PD, less activity among those with ICDs, greater activity in those without ICDs.	Most findings also suggest less activity in SUD groups than in controls.
Striatum	Baseline: Limited results have been variable regarding D2-like receptor availability in PG. Limited evidence suggests dorsal hyperactivity.	Reduced D2-like receptor availability in SUD/substance users. Dorsal hyperactivity in SUD also.
	Impulsivity and compulsivity tasks: Limited findings suggest no differences between PG and controls.	Limited findings suggest no differences between substance users and controls.
	Risk/reward tasks: In PG, less ventral activity than in controls and association with impulsivity. Some evidence of elevated dorsal activity in PG. Findings more variable in PD studies.	Some similar findings of diminished ventral activity in SUD/substance users with similar associations with impulsivity (particularly in alcoholism), but opposing findings of elevated activity as well.
Anterior cingulate cortex (ACC)	Findings that “loss chasing” is associated with elevated activity in healthy adults suggest a role in gambling.	Associated with risky decision-making in SUDs.
Insula	Activated by healthy adults and occasional gamblers during gambling tasks and by healthy adults in response to “near misses” during gambling tasks.	Activated in response to reward by substance users.
White matter integrity	PG reduced FA values in the corpus collosum	Poor white matter integrity observed diffusely both in heavy substance users and in SUDs

PD: Parkinson’s Disease, ICD: impulse control disorder, FA: fractional anisotropy