Differential effects of escitalopram on attention: a placebo-controlled, double-blind cross-over study

Anti-depressive-like and cognitive impairment alleviation effects of Gastrodia elata Blume water extract is related to gut microbiome remodeling in ApoE-/- mice exposed to unpredictable chronic mild stress

ETHNOPHARMACOLOGY RELEVANCE

Gastrodia elata Blume (GE) is a traditional Chinese dietary therapy used to treat neurological disorders. Gastrodia elata Blume water extract (WGE) has been shown to ameliorate inflammation and improve social frustration in mice in a chronic social defeat model. However, studies on the anti-depressive-like effects and cognitive impairment alleviation related to the impact of WGE on the gut microbiome of ApoE-/- mice remain elusive.

AIM OF THE STUDY

The present study aimed to investigate the anti-depressive-like effect and cognitive impairment alleviation and mechanisms of WGE in ApoE-/- mice subjected to unpredictable chronic mild stress (UCMS), as well as its impact on the gut microbiome of the mice.

MATERIALS AND METHODS

Sixty ApoE-/- mice (6 months old) were randomly grouped into six groups: control, UCMS, WGE groups [5, 10, 20 mL WGE/kg body weight (bw) + UCMS], and a positive group (fluoxetine 20 mg/kg bw + UCMS). After four weeks of the UCMS paradigm, the sucrose preference, novel object recognition, and open field tests were conducted. The neurotransmitters serotonin (5-HT), dopamine (DA) and their metabolites were measured in the prefrontal cortex. Serum was collected to measure corticosterone and amyloid-42 (Aβ-42) levels. Feces were collected, and the gut microbiome was analyzed.

RESULTS

WGE restored sucrose preference, exploratory behavior, recognition ability, and decreased the levels of serum corticosterone and Aβ-42 in ApoE-/- mice to alleviate depressive-like behavior and cognitive impairment. Furthermore, WGE regulated the monoamine neurotransmitter via reduced the 5-HT and DA turnover rates in the prefrontal cortex. Moreover, WGE elevated the levels of potentially beneficial bacteria such as Bifidobacterium, Akkermansia, Alloprevotella, Defluviitaleaceae_UCG-011, and Bifidobacterium pseudolongum as well as balanced fecal short-chain fatty acids (SCFAs).

CONCLUSION

WGE demonstrates anti-depressive-like effects, cognitive impairment alleviation, and gut microbiome and metabolite regulation in ApoE-/- mice. Our results support the possibility of developing a functional and complementary medicine to prevent or alleviate depression and cognitive decline using WGE in CVDs patients.

The attention-emotion interaction in healthy female participants on oral contraceptives during 1-week escitalopram intake

Previous findings in healthy humans suggest that selective serotonin reuptake inhibitors (SSRIs) modulate emotional processing via earlier changes in attention. However, many previous studies have provided inconsistent findings. One possible reason for such inconsistencies is that these studies did not control for the influence of either sex or sex hormone fluctuations. To address this inconsistency, we administered 20 mg escitalopram or placebo for seven consecutive days in a randomized, double-blind, placebo-controlled design to sixty healthy female participants with a minimum of 3 months oral contraceptive (OC) intake. Participants performed a modified version of an emotional flanker task before drug administration, after a single dose, after 1 week of SSRI intake, and after a 1-month wash-out period. Supported by Bayesian analyses, our results do not suggest a modulatory effect of escitalopram on behavioral measures of early attentional-emotional interaction in female individuals with regular OC use. While the specific conditions of our task may be a contributing factor, it is also possible that a practice effect in a healthy sample may mask the effects of escitalopram on the attentional-emotional interplay. Consequently, 1 week of escitalopram administration may not modulate attention toward negative emotional distractors outside the focus of attention in healthy female participants taking OCs. While further research in naturally cycling females and patient samples is needed, our results represent a valuable contribution toward the preclinical investigation of antidepressant treatment.

Difference in the regulation of biological rhythm symptoms of Major depressive disorder between escitalopram and mirtazapine

BACKGROUND

Biological rhythm plays an important role in major depressive disorder (MDD). The efficacy of antidepressant in biological rhythm remains unclear. This study is designed to explore the efficiency of escitalopram and mirtazapine in improving circadian rhythm, diurnal mood variation(DMV) and daily activity in MDD patients.

METHODS

Four-hundred and fifty participants diagnosed with MDD were randomized to receive treatment with escitalopram (TWE), treatment with mirtazapine (TWM) or treatment as usual (TAU). Biological rhythm symptoms were assessed by relevant biological subscale in the Hamilton depression scale (HAMD) and the quick inventory of depressive symptomatology self-report (QIDS). The participants were assessed by trained evaluators at baseline and week 2, 4, 6 and 8.

RESULTS

The differences of HAMD score among TWE(58%, 69%, 72%), TWM(56%, 64%, 76%) and TAU(49%, 57%, 68%) were significant(P<0.05). But the differences were significant only in patients without DMV; (2) Sleep rhythm items (difficulty falling asleep and early-wake) were significantly improved in TWM (P <0 .05) for both HAMD and QIDS. Decreased appetite and weight were significantly improved in TWM (P<0 .05) for both scales. (3) For daily activity-related items, feeling slowed down and concentration were significantly improved in TWE. And the retardation was significantly improved in TWE and in TWM.

CONCLUSIONS

Both escitalopram and mirtazapine have superior anti-depressive effect, especially for MDD patients without DMV. Escitalopram was significantly more effective in daily activity, feeling slowed down and concentration difficulty, while mirtazapine was significantly more effective in improving sleep, appetite and weight of MDD.

Goal Directed and Self-Control Systems in Bulimia Nervosa: An fMRI Study

Background

Binge eating is apparently the opposite of the strict control over food intake typically set by “maladaptive dieters”. Using functional magnetic resonance imaging (fMRI), we investigated the role of goal-directed behaviors, and the related use of self-control, in binge-related food choices in patients with Bulimia Nervosa (BN).

Method

While undergoing fMRI, women aged 18–35 with BN (N = 35) and healthy control women (N = 26) rated foods for healthiness and tastiness and then made food choices on a 5 points Likert scale between two conflicting options: one food with lower healthiness and higher tastiness (defined as uncontrolled choice) than the other food (defined as controlled choice).

Results

BN and healthy participants made more uncontrolled than controlled choices (63% vs 24% and 65% vs 18% respectively). While healthy participants used only food tastiness (chose tastier foods more often) to make food choices (p < .001), BN patients used both food healthiness (chose unhealthy food more often, p < .001) and food tastiness (p < .001) to make binge-related food choices. Activity in the ventromedial prefrontal cortex (vmPFC), which correlated with food choices (p_FWE = 0.02), reflected this difference in the integration of food healthiness and food tastiness into a decision value. Functional connectivity analysis showed that the activity in the dorsolateral prefrontal cortex was coupled with vmPFC activity in uncontrolled food choices (p_FWE = 0.03).

Interpretation

Contrary to what might be expected, not only food tastiness but also unhealthiness (a more abstract cognitive-based attribute than food tastiness) plays a role in uncontrolled choices in BN. These choices are likely goal-directed behaviors and recruit self-control.

Preference for Safe Over Risky Options in Binge Eating

Binge eating has been usually viewed as a loss of control and an impulsive behavior. But, little is known about the actual behavior of binging patients (prevalently women) in terms of basic decision-making under risk or under uncertainty. In healthy women, stressful cues bias behavior for safer options, raising the question of whether food cues that are perceived as threatening by binging patients may modulate patients’ behaviors towards safer options. A cross-sectional study was conducted with binging patients (20 bulimia nervosa (BN) and 23 anorexia nervosa binging (ANB) patients) and two control groups (22 non-binging restrictive (ANR) anorexia nervosa patients and 20 healthy participants), without any concomitant impulsive disorder. We assessed decisions under risk with a gambling task with known probabilities and decisions under uncertainty with the balloon analog risk taking task (BART) with unknown probabilities of winning, in three cued-conditions including neutral, binge food and stressful cues. In the gambling task, binging and ANR patients adopted similar safer attitudes and coherently elicited a higher aversion to losses when primed by food as compared to neutral cues. This held true for BN and ANR patients in the BART. After controlling for anxiety level, these safer attitudes in the food condition were similar to the ones under stress. In the BART, ANB patients exhibited a higher variability in their choices in the food compared to neutral condition. This higher variability was associated with higher difficulties to discard irrelevant information. All these results suggest that decision-making under risk and under uncertainty is not fundamentally altered in all these patients.

Common selective serotonin reuptake inhibitor side effects in older adults associated with genetic polymorphisms in the serotonin transporter and receptors: data from a randomized controlled trial

OBJECTIVE

Antidepressant side effects are a significant public health issue, associated with poor adherence, premature treatment discontinuation, and, rarely, significant harm. Older adults assume the largest and most serious burden of medication side effects. We investigated the association between antidepressant side effects and genetic variation in the serotonin system in anxious, older adults participating in a randomized, placebo-controlled trial of the selective serotonin reuptake inhibitor (SSRI) escitalopram.

METHODS

Adults (N = 177) aged ≥ 60 years were randomized to active treatment or placebo for 12 weeks. Side effects were assessed using the Udvalg fur Kliniske Undersøgelser side-effect rating scale. Genetic polymorphisms were putative functional variants in the promoters of the serotonin transporter and 1A and 2A receptors (5-HTTLPR [L/S + rs25531], HTR1A rs6295, HTR2A rs6311, respectively).

RESULTS

Four significant drug-placebo side-effect differences were found: increased duration of sleep, dry mouth, diarrhea, and diminished sexual desire. Analyses using putative high- versus low-transcription genotype groupings revealed six pharmacogenetic effects: greater dry mouth and decreased sexual desire for the low- and high-expressing serotonin transporter genotypes, respectively, and greater diarrhea with the 1A receptor low-transcription genotype. Diminished sexual desire was experienced significantly more by high-expressing genotypes in the serotonin transporter, 1A, or 2A receptors. There was not a significant relationship between drug concentration and side effects nor a mean difference in drug concentration between low- and high-expressing genotypes.

CONCLUSION

Genetic variation in the serotonin system may predict who develops common SSRI side effects and why. More work is needed to further characterize this genetic modulation and to translate research findings into strategies useful for more personalized patient care.

Improved planning abilities in binge eating

Objective

The role of planning in binge eating episodes is unknown. We investigated the characteristics of planning associated with food cues in binging patients. We studied planning based on backward reasoning, reasoning that determines a sequence of actions back to front from the final outcome.

Method

A cross-sectional study was conducted with 20 healthy participants, 20 bulimia nervosa (BN), 22 restrictive (ANR) and 23 binging anorexia nervosa (ANB), without any concomitant impulsive disorder. In neutral/relaxing, binge food and stressful conditions, backward reasoning was assessed with the Race game, promotion of delayed large rewards with an intertemporal discounting task, attention with the Simon task, and repeating a dominant behavior with the Go/No-go task.

Results

BN and to a lower extent ANB patients succeeded more at the Race game in food than in neutral condition. This difference discriminated binging from non-binging participants. Backward reasoning in the food condition was associated with lower approach behavior toward food in BN patients, and higher food avoidance in ANB patients. Enhanced backward reasoning in the food condition related to preferences for delayed large rewards in BN patients. In BN and ANB patients the enhanced success rate at the Race game in the food condition was associated with higher attention paid to binge food.

Conclusion

These findings introduce a novel process underlying binges: planning based on backward reasoning is associated with binges. It likely aims to reduce craving for binge foods and extend binge refractory period in BN patients, and avoid binging in ANB patients. Shifts between these goals might explain shifts between eating disorder subtypes.

Association entre l’anxiété et le déclin cognitif chez les personnes âgées vivant dans la communauté

The present study was conducted to determine whether anxiety among community-dwelling elders is associated with cognitive decline over a period of one year as well as to verify whether there are sex differences in the association between anxiety and cognitive decline. Participants (n=1942) were community-dwelling adults aged 65–96 years assessed at study entry (T0) and one year later (T1). Anxiety was identified with a semi-structured interview and cognitive functioning was assessed using the Mini-Mental State Examination. Results revealed that the presence of a clinically significant anxiety disorder did not predict cognitive decline in men and women. Subclinical anxiety symptoms predicted cognitive decline in women only. Moreover, for men, the presence of symptoms from at least two anxiety disorders predicted cognitive decline. For women, cognitive decline was predicted by the presence of symptoms from one anxiety disorder only. Overall, the results illustrate the role of anxiety in cognitive decline in community-dwelling older adults.

The role of 5-HT in response inhibition and re-engagement

In animal and human research, the neurotransmitter serotonin (5-HT) has been implicated in inhibitory control. Using functional magnetic resonance imaging (fMRI), the present study investigated the acute effects of pharmacological modulation of the serotonergic system on brain activation during response inhibition and re-engagement in healthy human volunteers. In a randomized double-blind placebo-controlled cross-over design 14 men received either a single oral dose of the selective serotonin reuptake inhibitor (SSRI) escitalopram (10mg) or a placebo. At the time of the expected plasma peak concentration, participants performed a stop-change task during fMRI. Escitalopram did not affect behavioural performance, since the main effect did not reveal significant differences between reaction times of go-, stop- or change-trials. During successful response inhibition, escitalopram, however, was associated with enhanced brain activation in right prefrontal cortex, right supplementary/pre-motor and bilateral cingulate cortex, and subcortical regions. During inhibition failures, escitalopram also modulated a broad network of brain regions, including anterior cingulate, right parietal cortex, right orbitofrontal cortex, and areas in right temporal cortex and subcortical regions. During response re-engagement escitalopram increased brain activation in right inferior frontal gyrus and precuneus as well as in left middle temporal gyrus. The results implicate the involvement of 5-HT in neural regulation of response inhibition and re-engagement. This study also provides evidence that 5-HT affects both action restraint and action cancellation through modulation of activation of brain areas. The results support the view for a fronto-striatal circuitry for response inhibition in conjunction with serotonin.

The role of serotonin in cognitive function: evidence from recent studies and implications for understanding depression

BACKGROUND

Symptoms of cognitive impairment such as poor concentration, memory loss and difficulty with decision making are prevalent in patients with depression, but currently are not specific targets for treatment. However, patients can continue to demonstrate cognitive impairments even when apparently clinically recovered. Drugs that potentiate serotonin (5-HT) function, such as selective serotonin reuptake inhibitors (SSRIs), are the mainstay of treatment for depression. Nevertheless, our understanding of the effects of SSRIs and other conventional antidepressant therapy on cognitive function in healthy humans and depressed patients remains limited.

OBJECTIVE

The purpose of this article is to provide a concise overview for clinicians on the impact of pharmacological manipulation of 5-HT on cognitive function in healthy humans with additional reference to animal models where human data are lacking, particularly regarding specific 5-HT receptor subtype modulation.

FINDINGS

The most consistent observation following manipulation of serotonin levels in humans is that low extracellular 5-HT levels are associated with impaired memory consolidation. Preclinical data show that agonism and antagonism at specific 5-HT receptors can exert effects in animal models of cognition.

CONCLUSIONS

Larger, consistently designed studies are needed to understand the roles of 5-HT in cognition in healthy and depressed individuals. Efforts to target specific 5-HT receptors to improve cognitive outcomes are warranted.

Escitalopram reduces attentional performance in anxious older adults with high-expression genetic variants at serotonin 2A and 1B receptors

Older adults are among the most vulnerable to adverse cognitive effects of psychotropic medications and, therefore, the personalization of psychotropic treatment based on adverse drug reactions in this demographic is of great importance. We examined changes on neuropsychological tests of attention attributable to selective serotonin reuptake inhibitor (SSRI) treatment in anxious older adults. We also examined whether variation in serotonin receptor genes was associated with reduced attentional performance with SSRIs. We examined change from pre- to post-treatment in two attention measures - digit span and coding - in 133 adults aged ≥60 yr with generalized anxiety disorder in a 12-wk trial of escitalopram vs. placebo. We also examined attentional change in relation to genetic variability in four central serotonin receptors: the serotonin transporter and serotonin 1A, 2A and 1B receptors. Digit span scores were significantly lowered in patients receiving escitalopram relative to placebo, indicating reduced attentional performance attributable to the SSRI. Individuals with high-transcription variants in the receptors 5-HTR2A rs6311 and 5-HTR1B rs11568817 had greater reductions in attention with SSRI treatment compared to placebo. We conclude that SSRIs reduce attention in older adults, particularly in those with high-expression genetic variants at the serotonin 2A and 1B receptors. Analysing neuropsychological changes with SSRIs in relation to genetic variation in the serotonin system may be a useful strategy for detecting subgroups of older adults who are more susceptible to side-effects of SSRIs. These results, if confirmed, could lead to the personalization of SSRI use to reduce adverse neurocognitive effects.

Modafinil, but not escitalopram, improves working memory and sustained attention in long-term, high-dose cocaine users

OBJECTIVE

The purpose of the present study was to determine the effects of modafinil, escitalopram, and modafinil + escitalopram administration on neurocognition in a sample of long-term, high-dose cocaine users.

METHOD

Sixty-one cocaine-dependent individuals were randomly assigned to receive placebo (n = 14), modafinil, 200 mg, once daily (n = 16), escitalopram, 20 mg, once daily (n = 16), or modafinil and escitalopram, once daily (n = 15), for five days on an inpatient basis. Urinanalysis was used to confirm abstinence from cocaine on the day of admission and the next five days. Baseline neurocognitive assessment, which included measures of attention/information processing, episodic memory, and working memory, was conducted immediately after the washout phase and prior to the administration of modafinil. The follow-up assessment was conducted after participants had received modafinil or placebo for five days.

RESULTS

Repeated-measures, mixed model analysis of variance showed that modafinil administration was associated with significantly improved performance on two measures of working memory span (mean n-back span, maximum n-back span) and a trend toward significant improvement on a measure of visual working memory (visual accuracy) and two measures of sustained attention, consistency of response time (Variability) and reduced impulsivity (Perseveration). Modafinil administration did not modulate performance on measures of information processing speed or episodic memory. Escitalopram did not modulate performance on measures of cognition, either alone or in combination with modafinil.

CONCLUSIONS

This study provides initial data showing that, in a sample of long-term, high-dose cocaine users, administration of psychotropic medications, such as modafinil, can improve performance on measures of working memory. Moreover, it confirms the utility of studying the interactive effects of psychotropic medications to confirm the manner in which the candidate medications independently and interactively affect neurocognition. These effects are likely relevant in the treatment of cocaine dependence, in which the remediation of impaired working memory may be associated with improved treatment outcomes. This article is part of a Special Issue entitled 'Cognitive Enhancers'.

Treatment-related alteration of cortisol predicts change in neuropsychological function during acute treatment of late-life anxiety disorder

OBJECTIVE

Older adults with anxiety disorders are burdened by impairment in neurocognition, which may be mediated by elevated circulating cortisol levels. In a randomized controlled trial of acute serotonin-reuptake inhibitor treatment for late-life anxiety disorder, we examined whether change in salivary cortisol concentrations during treatment predicted improvements in measures of memory and executive function.

METHODS

We examined 60 adults aged 60 years and older, who took part in a 12-week trial of escitalopram versus placebo for generalized anxiety disorder. All subjects had pre-treatment and post-treatment assessments that included monitoring of peak and total daily cortisol and a comprehensive neuropsychological evaluation.

RESULTS

Salivary cortisol changes during treatment showed significant associations with changes in immediate and delayed memory but no association with executive tasks (measures of working memory and set shifting). Analyses suggested that a decrease in cortisol due to serotonin-reuptake inhibitor treatment was responsible for the memory changes: memory improvement was seen with cortisol reduction among patients receiving escitalopram but not among patients receiving placebo.

CONCLUSION

Serotonin-reuptake inhibitor-induced alteration in circulating cortisol during treatment of generalized anxiety disorder predicted changes in immediate and delayed memory. This finding suggests a novel treatment strategy in late-life anxiety disorders: targeting hypothalamic-pituitary- adrenal axis dysfunction to improve memory.

A randomized trial of the effect of escitalopram versus placebo on cognitive function in healthy first-degree relatives of patients with depression

The effect of selective serotonin receptor inhibitors (SSRIs) on healthy individuals remains unclear. The aim of the trial was to evaluate the effect of the SSRI escitalopram on cognitive function in healthy first-degree relatives of patients with major depressive disorder (FDRs). A total of 80 FDRs were randomized to escitalopram (10 mg/day) (n = 41) versus placebo (n = 39) for 4 weeks. Neuropsychological tests and ratings of mood were applied at entry (T0) and at 4 weeks (T4). The main outcome measure was calculated as the change (T4-T0) in a general cognition score, which was the standardized mean of 13 test measures. Mean change in the general cognition score was not significantly increased with escitalopram compared with placebo (p = 0.37) or for any of the specific tests. In univariate analyses no statistically significant correlations were found between change in the general cognitive score and the variables age, sex, Hamilton depression score 17 items, Danish Adult Reading Test-45, and plasma escitalopram levels, respectively. These results suggest that treatment with escitalopram does not improve or impair cognitive function in FDRs. Improvement in cognitive function following treatment of depressed patients with SSRIs seems to be related to the effects on depressive symptoms rather than to a direct effect of the SSRI.

Visual and auditory perceptual rivalry in migraine

INTRODUCTION

Recent evidence demonstrates that perceptual rivalry rate can be modulated by perturbation of the serotonergic system. Specifically, pharmacologically lowering the availability of serotonin results in slower rivalry rates. As it has been suggested that brain serotonin is low during the interictal phase of migraine, we hypothesized that perceptual rivalry rates would be reduced in individuals with migraine.

METHODS

Visual and auditory perceptual rivalry measures were obtained for a group of 30 participants with migraine (15 migraine with aura, 15 migraine without aura) and 20 non-headache control individuals.

RESULTS

Our experiments reveal fewer perceptual rivalry switches within both visual and auditory domains for our migraine without aura group, while the with-aura group performed similarly to non-headache controls. Dividing the data by headache frequency rather than headache subtype classification revealed fewer perceptual switches in those with more frequent headaches.

CONCLUSIONS

Our data provides further support for interictal differences in brain sensory reactivity in migraine, with the observed effects being in the same direction as those caused by pharmacologically reducing brain availability of serotonin in normal observers.

Serotonin transporter allelic variation in mothers predicts maternal sensitivity, behavior and attitudes toward 6-month-old infants

Maternal behavior in the new mother is a multidimensional set of responses to infant cues that are influenced by the mother's early life experiences. In this study, we wanted to test if mothers' early life experiences and mothers' genotype have interactive effects on maternal behaviors and attitudes, something which has not been previously explored. In a sample of 204 mothers, we assessed maternal genotype at the serotonin transporter-linked polymorphic region (5-HTTLPR) and an adjacent upstream polymorphism (rs25531), together giving rise to three alleles: short (S), L(G) and L(A). Controlling for maternal age and parity, we showed that this genotype can predict differences in maternal sensitivity at 6 months postpartum: mothers with an S (or the functionally similar L(G)) allele were more sensitive than mothers who lacked the allele during a 30-min recorded mother-infant interaction (F (4,140) = 3.43; P = 0.01). Furthermore, we found highly significant gene-environment interactions in association with maternal behavior, such that mothers with no S or L(G) alleles oriented away more frequently from their babies if they also reported more negative early care quality (F (5,138) = 3.28; P = 0.008). Finally, we found significant gene-environment associations with maternal attitudes; mothers with the S allele and with greater early care quality scored higher on ratings of their perceived attachment to their baby (F (5,125) = 3.27; P = 0.008). The regression results show significant interactions between the reported quality of care mothers received from their own parents and genotype on both their frequency of orienting away from the infant during the interaction (F(5, 138) = 3.28; P = 0.008, Fig. 1a) and their perceived attachment feelings to the infant (F(5, 125) = 3.27; P = 0.008, Fig. 1b); however the direction of the effects for these two outcome measures were different from one another. With increasing care quality, mothers with the L(A)L(A) genotype (no S or L(G) allele) oriented away less frequently, while S or L(G) allele carriers showed no significant change. In contrast, with increasing early care quality. L(A)L(A) (no S or L(G) allele) mothers scored lower on perceived attachment to their infants, whereas S or L(G) allele carrying mothers scored higher. [corrected].

Serotonergic modulation of response inhibition and re-engagement? Results of a study in healthy human volunteers

OBJECTIVE

Cognitive functions dependent on the prefrontal cortex, such as the ability to suppress behavior (response inhibition) and initiate a new one (response re-engagement) is important in the activities of daily life. Central serotonin (5-HT) function is thought to be a critical component of these cognitive functions. In recent studies, 5-HT failed to affect stop-signal reaction time (SSRT), a fundamental process in behavioral inhibition. We were interested if response inhibition and re-engagement are influenced through central 5-HT activity as mediated via the 5-HT transporter.

METHODS

Here, using a stop-change task, we investigated the effects of acute and repeated treatment with 10 mg escitalopram, a selective 5-HT reuptake inhibitor, in 36 healthy human volunteers on response inhibition and re-engagement in a randomized, double-blind, placebo-controlled study with cross-over design.

RESULTS

Results do not show an influence of escitalopram on response inhibition or response re-engagement as we did not find differences in SSRT or change reaction time (CRT).

CONCLUSIONS

These findings support the results of previous studies suggesting that 5-HT is not critical in inhibition of already initiated responses and response re-engagement. We hypothesize that results are due to different forms of behavioral inhibition and 5-HT may critical to other forms.