Greater Monoamine Oxidase a Binding in Alcohol Dependence

Background: Alcohol dependence (AD) is a multiorgan disease in which excessive oxidative stress and apoptosis are implicated. Monoamine oxidase A (MAO-A) is an important enzyme on the outer mitochondrial membrane that participates in the cellular response to oxidative stress and mitochondrial toxicity. It is unknown whether MAO-A levels are abnormal in AD. We hypothesized that MAO-A VT, an index of MAO-A level, is elevated in the prefrontal cortex (PFC) during AD, because markers of greater oxidative stress and apoptosis are reported in the brain in AD and a microarray analysis reported greater MAO-A messenger RNA in the PFC of rodents exposed to alcohol vapor.

Methods: Sixteen participants with alcohol dependence and 16 healthy control subjects underwent [(11)C]-harmine positron emission tomography. All were nonsmoking, medication- and drug-free, and had no other past or present psychiatric or medical illnesses.

Results: MAO-A VT was significantly greater in the PFC (37%, independent samples t test, t₃₀ = 3.93, p < .001), and all brain regions analyzed (mean 32%, multivariate analysis of variance, F₇,₂₄ = 3.67, p = .008). Greater duration of heavy drinking correlated positively with greater MAO-A VT in the PFC (r = .67, p = .005) and all brain regions analyzed (r = .73 to .57, p = .001-.02).

Conclusions: This finding represents a new pathological marker present in AD that is therapeutically targetable through direct inhibition or by novel treatments toward oxidative/pro-apoptotic processes implicated by MAO-A overexpression.