Introduction
MDD, cognitive and affective brain functions, neuropsychiatric disorders
COLD
Serotonin or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter implicated in several cognitive and affective brain functions [Many studies examining the modulatory effects of serotonin on cognition have been conducted in experimental animals [In humans, the modulatory effects of serotonin on cognition have largely been examined through acute dietary tryptophan depletion (ATD) [Given that SSRIs are administered chronically in the treatment of neuropsychiatric disorders, it is particularly important to understand the long-term effects of SSRI administration on cognition. Currently, only a few studies have examined SSRIs administered sub-chronically, over approximately 7 days [Understanding the acute effects of SSRIs on cognitive processes in healthy volunteers and patients with MDD is complex. This may be due to the differing possible pre- and post-synaptic actions [Escitalopram is the active S-enantiomer of the racemic SSRI citalopram (RS-citalopram) [In the present study, we used a double-blind placebo-controlled design to examine the effects of the SSRI escitalopram administered on average for 26 days, on a comprehensive set of measures of ‘cold’ and, ‘hot’ cognition, including decision-making and computational measures of reinforcement learning. We hypothesised that SSRI treatment would affect reinforcement-related behaviour, probabilistic reversal learning, and response inhibition.