Face processing in chronic alcoholism: a specific deficit for emotional features

Alcoholism and dampened temporal limbic activation to emotional faces

BACKGROUND

Excessive chronic drinking is accompanied by a broad spectrum of emotional changes ranging from apathy and emotional flatness to deficits in comprehending emotional information, but their neural bases are poorly understood.

METHODS

Emotional abnormalities associated with alcoholism were examined with functional magnetic resonance imaging in abstinent long-term alcoholic men in comparison to healthy demographically matched controls. Participants were presented with emotionally valenced words and photographs of faces during deep (semantic) and shallow (perceptual) encoding tasks followed by recognition.

RESULTS

Overall, faces evoked stronger activation than words, with the expected material-specific laterality (left hemisphere for words, and right for faces) and depth of processing effects. However, whereas control participants showed stronger activation in the amygdala and hippocampus when viewing faces with emotional (relative to neutral) expressions, the alcoholics responded in an undifferentiated manner to all facial expressions. In the alcoholic participants, amygdala activity was inversely correlated with an increase in lateral prefrontal activity as a function of their behavioral deficits. Prefrontal modulation of emotional function as a compensation for the blunted amygdala activity during a socially relevant face appraisal task is in agreement with a distributed network engagement during emotional face processing.

CONCLUSIONS

Deficient activation of amygdala and hippocampus may underlie impaired processing of emotional faces associated with long-term alcoholism and may be a part of the wide array of behavioral problems including disinhibition, concurring with previously documented interpersonal difficulties in this population. Furthermore, the results suggest that alcoholics may rely on prefrontal rather than temporal limbic areas in order to compensate for reduced limbic responsivity and to maintain behavioral adequacy when faced with emotionally or socially challenging situations.

Impaired emotional facial expression decoding in alcoholism is also present for emotional prosody and body postures

AIMS

Emotional facial expression (EFE) decoding impairment has been repeatedly reported in alcoholism (e.g. Philippot et al., 1999). Nevertheless, several questions are still under debate concerning this alteration, notably its generalization to other emotional stimuli and its variation according to the emotional valence of stimuli.

METHODS

Eighteen recently detoxified alcoholic subjects and 18 matched controls performed a decoding test consisting in emotional intensity ratings on various stimuli (faces, voices, body postures and written scenarios) depicting different emotions (anger, fear, happiness, neutral, sadness). Perceived threat and difficulty were also assessed for each stimulus.

RESULTS

Alcoholic individuals had a preserved decoding performance for happiness stimuli, but alcoholism was associated with an underestimation of sadness and fear, and with a general overestimation of anger. More importantly, these decoding impairments were observed for faces, voices and postures but not for written scenarios.

CONCLUSIONS

We observed for the first time a generalized emotional decoding impairment in alcoholism, as this impairment is present not only for faces but also for other visual (i.e. body postures) and auditory stimuli. Moreover, we report that this alteration (1) is mainly indexed by an overestimation of anger and (2) cannot be explained by an 'affect labelling' impairment, as the semantic comprehension of written emotional scenarios is preserved. Fundamental and clinical implications are discussed.