Information processing in anxiety: a pilot study of the effect of manipulating 5-HT function

Sack A, Fecteau S. Characterizing emotional Stroop interference in posttraumatic stress disorder, major depression and anxiety disorders: A systematic review and meta-analysis

BACKGROUND

Posttraumatic stress disorder is a debilitating psychiatric disorder characterized by symptoms of intrusive re-experiencing of trauma, avoidance and hyper-arousal. Diagnosis and treatment of PTSD is further complicated by concurrently occurring disorders, the most frequent being major depressive disorder and anxiety disorders. Previous research highlights that attentional processing in posttraumatic stress disorder is associated with substantial interference by emotional stimuli, a phenomenon also observed in these concurrently occurring psychiatric disorders. However, the diagnosis-relevance of this interference remains elusive. Here, we investigated the emotional Stroop interference for diagnosis-related stimuli, generally negative stimuli, and generally positive stimuli in posttraumatic stress disorder, major depressive disorder and anxiety disorders.

METHODS

We performed a systematic database search in PubMed (Medline), Cochrane Library and PsycINFO on emotional Stroop performance in individuals with a diagnosis of posttraumatic stress disorder, major depressive disorder or anxiety disorders separately. Mean effect sizes, standard errors and confidence intervals were estimated for each clinical group and healthy control group comparison using random effect models.

RESULTS

As compared to healthy control group, the posttraumatic stress disorder group displayed greater interference by diagnosis-related stimuli and positive stimuli but not for generally negative stimuli. The major depressive disorder and anxiety disorders groups showed greater interference by diagnosis-related and negative stimuli, but not by positive stimuli. The age and sex had no significant impact on interference.

CONCLUSIONS

These findings highlight the importance of diagnosis-relevant information on attentional processing in all three clinical populations, posttraumatic stress disorder, major depressive disorder and anxiety disorders. Further, the impact of generally negative stimuli but not generally positive stimuli in major depressive disorder and anxiety disorders indicate impaired attentional bias for mood-congruent stimuli but not for general stimuli. Finally, it remains to be studied whether the influence of generally positive stimuli in posttraumatic stress disorder indicate that positive stimuli are perceived as PTSD related.

Acute effects of the designer drugs benzylpiperazine (BZP) and trifluoromethylphenylpiperazine (TFMPP) using functional magnetic resonance imaging (fMRI) and the Stroop task--a pilot study

RATIONALE

A novel group of designer drugs containing benzylpiperazine (BZP) and/or trifluoromethylphenylpiperazine (TFMPP) have been available worldwide for more than a decade; however, their effects on human brain function have not been extensively described.

OBJECTIVES

In a double-blind, placebo-controlled crossover study, the acute effects of BZP and TFMPP (alone and in combination) on the neural networks involved in executive function were investigated using an event-related Stroop functional magnetic resonance imaging (fMRI) paradigm.

METHODS

Thirteen healthy participants aged 18-40 years undertook the Stroop task 90 min after taking an oral dose of either BZP (200 mg), TFMPP (either 50 or 60 mg), BZP + TFMPP (100 + 30 mg) or placebo. A change in activity in neural regions reflects an increase in local demand for oxygen, due to an increase in neuronal activity.

RESULTS

Relative to placebo, an increase in neural activation was observed in the dorsal striatum following BZP, and in the thalamus following TFMPP, when performing the Stroop task.

CONCLUSION

These data suggest that additional compensatory resources were recruited to maintain performance during the Stroop task. When BZP and TFMPP were administered together, both the dorsal striatum and thalamus were activated. However, the combination of BZP/TFMPP attenuated activation in the caudate, possibly due to TFMPP's indirect effects on dopamine release via 5HT2C receptors.

Psilocybin-induced deficits in automatic and controlled inhibition are attenuated by ketanserin in healthy human volunteers

The serotonin-2A receptor (5-HT(2A)R) has been implicated in the pathogenesis of schizophrenia and related inhibitory gating and behavioral inhibition deficits of schizophrenia patients. The hallucinogen psilocybin disrupts automatic forms of sensorimotor gating and response inhibition in humans, but it is unclear so far whether the 5-HT(2A)R or 5-HT(1A)R agonist properties of its bioactive metabolite psilocin account for these effects. Thus, we investigated whether psilocybin-induced deficits in automatic and controlled inhibition in healthy humans could be attenuated by the 5-HT(2A/2C)R antagonist ketanserin. A total of 16 healthy participants received placebo, ketanserin (40 mg p.o.), psilocybin (260 μg/kg p.o.), or psilocybin plus ketanserin in a double-blind, randomized, and counterbalanced order. Sensorimotor gating was measured by prepulse inhibition (PPI) of the acoustic startle response. The effects on psychopathological core dimensions and behavioral inhibition were assessed by the altered states of consciousness questionnaire (5D-ASC), and the Color-Word Stroop Test. Psilocybin decreased PPI at short lead intervals (30 ms), increased all 5D-ASC scores, and selectively increased errors in the interference condition of the Stroop Test. Stroop interference and Stroop effect of the response latencies were increased under psilocybin as well. Psilocybin-induced alterations were attenuated by ketanserin pretreatment, whereas ketanserin alone had no significant effects. These findings suggest that the disrupting effects of psilocybin on automatic and controlled inhibition processes are attributable to 5-HT(2A)R stimulation. Sensorimotor gating and attentional control deficits of schizophrenia patients might be due to changes within the 5-HT(2A)R system.

Negative affect predicts subsequent cognitive change in multiple sclerosis

Baseline predictors of cognitive change were explored in a sample of persons with multiple sclerosis (MS). Potential predictors included demographic features, baseline clinical characteristics, and psychological state. Participants were 38 individuals diagnosed with either relapsing remitting or secondary progressive MS who did not meet criteria for a current major depressive episode. Subjects were tested at baseline and approximately 1 year in an ongoing longitudinal study of cognition in MS. Participants completed neuropsychological tests sensitive to impairment in MS. They also completed self-report measures of depression, anxiety, fatigue, apathy, and positive and negative affect. Baseline measures of negative affect (e.g., depressed mood, state anxiety, and negative affective state) consistently predicted cognitive change over the course of the study. Higher baseline levels of negative affect were associated with greater relative declines in cognitive performance. This longitudinal relation occurred in the absence of a cross-sectional relation between negative affect and overall cognition. High baseline negative affect particularly predicted a relative decline in episodic memory for newly learned verbal and visuospatial information. The negative affect measures were unique in their predictive value among all the baseline measures assessed. (JINS, 2009, 15, 53-61.).

The automaticity of emotional Stroop: a meta-analysis

An automatic bias to threat is often invoked to account for colour-naming interference in emotional Stroop. Recent findings by McKenna and Sharma [(2004). Reversing the emotional Stroop effect reveals that it is not what it seems: The role of fast and slow components. Journal of Experimental Psychology: Learning, Memory, and Cognition, 30, 382-392], however, cast doubt on the fast and non-conscious nature of emotional Stroop. Interference by threat words only occurred with colour naming in the trial subsequent to the threat trial (i.e., a "slow" effect), but not immediately (i.e., a "fast" effect, as would be predicted by the bias hypothesis). In a meta-analysis of 70 published emotional Stroop studies the largest effects occurred when presentation of threat words was blocked, suggesting a strong contribution by slow interference. We did not find evidence; moreover, for interference in suboptimal (less conscious) presentation conditions and the only significant effects were observed in optimal (fully conscious) conditions with high-anxious non-clinical participants and patients. The emotional Stroop effect seems to rely more on a slow disengagement process than on a fast, automatic, bias.

The effect of citalopram pretreatment on neuronal responses to neuropsychological tasks in normal volunteers: an FMRI study

Changes in serotonin neurotransmission have also been implicated in the etiology and treatment of impulse control disorders, depression, and anxiety. We have investigated the effect of enhancing serotonin function on fundamental brain processes that we have proposed are abnormal in these disorders. In all, 12 male volunteers received citalopram (7.5 mg intravenously) and placebo pretreatment in a single-blind crossover design before undertaking Go/No-go, Loss/No-loss, and covert (aversive) face emotion recognition tasks during functional magnetic resonance imaging (fMRI). Blood oxygenation level dependent responses were analyzed using Statistical Parametric Mapping (SPM2). The tasks activated prefrontal and subcortical regions generally consistent with literature with lateral orbitofrontal cortex (BA47) common to the three tasks. Citalopram pretreatment enhanced the right BA47 responses to the No-go condition, but attenuated this response to aversive faces. Attenuations were seen following citalopram in the medial orbitofrontal (BA11) responses to the No-go and No-loss (ie relative reward compared with Loss) conditions. The right amygdala response to aversive faces was attenuated by citalopram. These results support the involvement of serotonin in modulating basic processes involved in psychiatric disorders but argue for a process-specific, rather than general effect. The technique of combining drug challenge with fMRI (pharmacoMRI) has promise for investigating human psychiatric disorders.

Effect of short-term SSRI treatment on cognitive bias in generalised anxiety disorder

RATIONALE

There is considerable evidence showing that individuals with generalised anxiety disorder (GAD) selectively process threat-related information, e.g. they have a bias to interpret ambiguous information in a threat-related manner. Cognitive theories of anxiety, which provide the basis of cognitive-behaviour therapy, propose that such processing biases play an important role in causing and maintaining anxiety.

OBJECTIVES

Given that treatment with selective serotonin re-uptake inhibitors (SSRIs) appears to be effective for GAD, we examined whether it is successful in removing cognitive bias.

METHODS

The clinical group included 19 patients with a diagnosis of GAD, and the control group consisted of a non-clinical sample of volunteers, matched for age, gender and years in education. The patients were assessed on measures of interpretative bias (homophone task), anxiety and depression before being prescribed an SSRI (paroxetine or citalopram). After 4 weeks, the cognitive task and mood measures were repeated in the patient group.

RESULTS

Prior to treatment, the GAD group showed a significantly greater level of threat-related interpretive bias than controls. Following SSRI treatment, there were significant reductions in both interpretive bias and in anxiety levels in the GAD group. Furthermore, individuals who showed greater clinical improvement (e.g. reflected by reduced anxiety scores) showed a correspondingly greater reduction in their cognitive bias.

CONCLUSION

The results suggest that SSRIs are effective in modifying both subjective anxiety levels and threat-related interpretive bias.

Drug craving and addiction: integrating psychological and neuropsychopharmacological approaches

In the present review, an integrated approach to craving and addiction is discussed, which is based on recent insights from psychology and neuropsychopharmacology. An integrated model explains craving and relapse in humans by the psychological mechanism of "attentional bias" and provides neuropsychopharmacological mechanisms for this bias. According to this model, cognitive processes mediate between drug stimulus and the subject's response to this stimulus and subsequent behavioral response (e.g., drug use, relapse). According to the model, a conditioned drug stimulus produces an increase in dopamine levels in the corticostriatal circuit, in particular the anterior cingulate gyrus, amygdala, and nucleus accumbens, which in turn serves to draw the subject's attention towards a perceived drug stimulus. This process results in motor preparation and a hyperattentive state towards drug-related stimuli that, ultimately, promotes further craving and relapse. Evidence for this attentional bias hypothesis is reviewed from both the psychopharmacological and the neuroanatomical viewpoints. The attentional bias hypothesis raises several suggestions for clinical approaches and further research.

Critical flicker frequency for quantification of low-grade hepatic encephalopathy

Subclinical hepatic encephalopathy (SHE) is currently diagnosed by psychometric tests or neurophysiologic techniques. In view of its sociomedical relevance, simple and reproducible tests for routine diagnosis are required. This study evaluates critical flicker-frequency thresholds for quantification of low-grade hepatic encephalopathy. A total of 115 patients (92 with cirrhosis, 23 controls) were analyzed for HE severity (mental state, computerized psychometric tests), and the threshold frequencies at which light pulses are perceived as fused (fusion frequency) or flickering light (critical flicker frequency [CFF]). CFF was a highly reproducible parameter with little age, day-time, and training dependency. CFFs in cirrhotic patients without HE (HE 0) were not different from those found in noncirrhotic controls. Significantly lower CFFs were found in cirrhotic patients with subclinical or manifest HE, and the various HE groups separated from each other at a high level of significance (P <.01). By using a CFF cut-off value of 39 Hz, a 100% separation of patients with manifest HE from noncirrhotic controls and HE 0 cirrhotic patients was obtained. SHE patients separated from HE 0 cirrhotic patients with high sensitivity (55%) and specificity (100%). The HE severity-dependent differences were found in both, alcoholic and posthepatitic cirrhosis. Statistically significant correlations (P <.01) were found between CFFs and individual psychometric tests. Aggravation of preexisting HE after transjugular intrahepatic portosystemic stent shunt (TIPS) implantation was accompanied by a corresponding decrease of CFF, whereas improvement of HE increased CFF. In conclusion, CFF is a sensitive, simple, and reliable parameter for quantification of low-grade HE severity in cirrhotic patients and may be useful for the detection and monitoring of SHE.

Cognitive interference is associated with neuronal marker N-acetyl aspartate in the anterior cingulate cortex: an in vivo (1)H-MRS study of the Stroop Color-Word task

The neurobiology of cognitive interference is unknown. Previous brain imaging studies using the Stroop Color-Word (SCW) task indicate involvement of the cingulate cortex cognitive division. The present study examines interrelationships between regional brain N-Acetyl aspartate (NAA) levels (as identified by in vivo proton magnetic resonance spectroscopy in the right and left anterior cingulate cortex (ACC), dorsolateral prefrontal cortex, orbitofrontal cortex and thalamus) and cognitive interference (as measured by the SCW task) in 15 normal subjects. The results show that brain chemistry depends on cognitive interference levels (high vs low). Reduction of NAA levels was demonstrated in the right ACC (ie, cognitive midsupracallosal division) of high interference subjects, as compared to the low interference group (P < 0.01, two-tailed t-test). Chemical-cognitive relationships were analyzed by calculating correlations between regional NAA levels and the SCW task scores. Cognitive interference was highly correlated with the right anterior cingulate NAA (r = 0.76, P < 0.001), and was unrelated to other studied regional NAA, including the left ACC (P < 0.025; comparing the difference between r values in the right and left ACC). The interrelationships between NAA across brain regions were examined using correlation analysis (square matrix correlation maps), which detected different connectivity patterns between the two groups. These findings provide evidence of ACC involvement in cognitive interference suggesting a possibility of neuronal reorganization in the physiological mechanism of interference (most likely due to genetically predetermined control of the number of neurons, dendrites and receptors, and their function). We conclude that spectroscopic brain mapping of NAA, the marker of neuronal density and function, to the SCW task measures differentiates between high and low interference in normal subjects. This neuroimaging/cognitive tool may be useful for documentation of interference in studying cognitive control mechanisms, and in diagnosis of neuropsychiatric disorders where dysfunction of cingulate cortex is expected.