Recovery of cortical functioning in abstinent alcohol-dependent patients: prefrontal brain oxygenation during verbal fluency at different phases during withdrawal.

OBJECTIVES: Neurotoxic effects of alcohol consumption are well-known. There is plenty of literature on frontal lobe impairment on the behavioural and structural brain imaging level. However, only few functional imaging studies investigated altered neural patterns and even less abstinence-related neural recovery.
METHODS: In a cross-sectional design three patient groups (acute withdrawal, detoxified, abstinent) and healthy controls (each n = 20) performed a phonological and semantic verbal fluency task (VFT) while brain activity was measured with near-infrared spectroscopy (NIRS).
RESULTS: First, for the phonological condition withdrawal patients and detoxified patients showed less fluency-related frontal lobe activation compared to controls despite equal performance. Second, significant linear trend effects from withdrawal patients over detoxified and abstinent patients up to healthy controls indicated more normal activation patterns in the abstinent group that did not differ significantly from the controls. In the detoxified group brain activation increased with time since detoxification.
CONCLUSIONS: Our results are compatible with an increase in frontal brain activity from alcohol dependence over abstinence up to normal functioning. However, as cross-sectional designs do not allow to assess causal relations, results have to be considered preliminary and longitudinal studies are needed to further elucidate recovery processes in alcohol dependence.