“Antidepressants can cause ‘emotional blunting’, study shows”, said the Grauniad today. The study by Langley et al. (2023) randomised 66 healthy participants (i.e., not requiring antidepressants) to either SSRI (20 mg of escitalopram – a high dose) or placebo, daily for 21 days.
I have two brief observations:
Almost all the statistical analyses were classical, with 95% confidence intervals including zero interpreted as not statistically significant. The authors’ headline-grabbing finding, concerning reinforcement sensitivity, was for one of four outcomes modelled using hierarchical Bayesian modelling. A 90% highest density interval excluded zero. However, the 95% interval included zero, so following the conventions of the rest of the paper would be counted as a null effect. There was no comment on this in the paper, which strikes me as a little odd, particularly given the large number of preregistered study outcome measures (16 primary, 44 secondary, 32 other) and consequent risk of a false positive.
Additionally, the headlines and study’s conclusion claim that their findings may explain the emotional blunting sometimes reported by users of SSRIs. But I don’t see how emotional blunting relates to the probabilistic reversal learning task the authors used.
I hope the study receives critical scrutiny in the press.
Langley, C., Armand, S., Luo, Q. et al. Chronic escitalopram in healthy volunteers has specific effects on reinforcement sensitivity: a double-blind, placebo-controlled semi-randomised study. Neuropsychopharmacol. (2023).