Emotion recognition processing as early predictor of response to 8-week citalopram treatment in late-life depression

In subjects with depression, exposure to antidepressants improves recognition of positive emotions. This phenomenon, which occurs early in the course of treatment, has been proposed as the initial step in the mechanism of action to subsequent therapeutic effects of antidepressants. To this date, it has not been well examined among older depressed patients.

Older subjects with non-psychotic major depressive disorder were treated with citalopram in an 8-week open-label study. The main predictor of response and remission was the change in emotion recognition between baseline and day 7. Covariates included executive functions, baseline anxiety level, medical comorbidity, level of subjective stress, serum citalopram level, and level of social support.

Twenty-seven patients were considered for final analysis. Overall, accuracy of emotion recognition significantly improved between baseline (75%) and day 7 (83%) (X(2)  = 34.50, df = 1, p < 0.001). Improvement to identify happy expressions occurred at 25% and 50% intensity with ceiling effect at 0%, 75%, and 100%. Change in emotion processing was marginally significant in predicting antidepressant response at day 56. Multivariate analysis showed that emotion processing is a significant predictor of response and remission when considered along with perceived level of social support.

Recognition of mildly intense happy expression, which improved early in the course of citalopram treatment, predicts subsequent antidepressant response and remission when considered along with perception of social support. Further studies would be necessary to examine specific neural substrates in the affective network involved in the acute therapeutic action of antidepressant in late-life depression.