Amantadin reduces activation of the cingulate gyrus in patients with obsessive-compulsive disorder: a LORETA based study

Amantadine is used as an effective compound in a variety of psychiatric disorders, though its clinically relevant pharmacodynamic properties are still unclear. In this study the influence of amantadine on obsessive-compulsive symptoms and attention deficits in patients with OCD (n=12) was investigated in a placebo-controlled trial using visual event-related brain potentials before and after 8 weeks of treatment. The stimulus material consisted of letters H and O with two varying sizes (larger ones as targets requiring response by pressing buttons, smaller ones as non-targets) in a go/nogo paradigm. Neural generators of the brain activity were estimated by computing the cortical distribution of current density with the LORETA algorithm. Statistical comparison for the target P3b (460–680ms) using the „statistical non-parametric mapping“ option for activity revealed significant lower localized brain activations of the cingulate gyrus within the amantadine group after treatment (p<0.05; BA 31) but not within the placebo group (p=0.61). Moreover, the reduction of the parietal P3b correlates with a decrease of obsessive symptoms in the amantadine group (r=0.82, p<0.05). Regarding to the deficits in high-order cognitive processes associated with OCD it has been hypothesized that hyperactive corticostriatal circuits constitute the underlying pathophysiology. Our findings suggest that amantadine could reduce this hyperactivation whereas the detailed mechanism remains to be discussed.