Frontal cortex gray matter volume alterations in pathological gambling occur independently from substance use...

Neuroimaging in pathological gambling (PG) allows studying brain structure independent of pharmacological/neurotoxic effects occurring in substance addiction. Because of high comorbidity of PG with substance use disorder (SUD), first results on structural deficits in PG are controversial. The current investigation is the first to examine gray matter (GM) volume alterations in PG controlling for the impact of SUD by comparing non-comorbid (PG_PURE ) and two comorbid (PG_ALCOHOL and PG_POLY ) groups. Two hundred and five individuals were included in the analysis: 107 patients diagnosed with PG and 98 healthy controls (HCs). We employed voxel-based morphometry to look for GM volume differences between the groups controlling for age, smoking and depression. GM decreases in the superior medial and orbital frontal cortex occur independently of substance use in PG_PURE compared with HCs. The frontal pattern of GM decrease was comparable with PG_ALCOHOL group where additionally GM volume was decreased in the anterior cingulate but increased in the amygdala. Moreover, regions in PG_{ALCOHOL + POLY} with reduced GM volume were the medial frontal, anterior cingulate and occipital lobe regions. PG_{ALCOHOL + POLY} not only exhibited structural deficits in comparison with HCs but also relative to PG_PURE in the precuneus and post-central gyrus. We demonstrated specific frontal cortex GM deficits in PG without SUD comorbidities. Whereas some target regions reported in earlier studies might result from comorbid substance abuse, there seems to be a core set of frontal alterations associated with addicted gambling behaviour independent of toxic substance effects.