Altered frontal brain oxygenation in detoxified alcohol dependent patients with unaffected verbal fluency performance

Abstract 

Despite prominent prefrontal deficits and alterations in anatomy, neurophysiology, and neuropsychology after long-term alcohol consumption in alcohol dependent patients, only a few investigations of functional brain activity have been published. Using functional near-infrared spectroscopy (fNIRS), we examined the concentration changes in oxygenated (O₂Hb) and deoxygenated (HHb) haemoglobin in 17 right-handed alcohol dependent patients after detoxification and 17 matched healthy controls during a verbal fluency task. Alcohol dependent patients were characterized by normal behavioural performance (number of words produced) and physiological activation patterns (increase of O₂Hb and decrease of HHb) over frontotemporal regions during phonological and semantical verbal fluency. However, the degree of activation was diminished (lower magnitude of oxygenation) and the localization of the activation was more restricted to inferior frontal areas as compared with the healthy participants. fNIRS is a sensitive and valid method, to detect alterations in brain functioning in clinical groups like alcohol dependent patients. Altered prefrontal functional brain activation during verbal fluency in alcohol dependent patients in a detoxified state may precede behavioural or cognitive alterations with a later onset.

Keywords: Alcoholism, Executive function, Forebrain, Functional imaging, NIRS, Verbal fluency