Paroxetine-induced modulation of cortical activity supporting language representations of action

The fNIRS evaluation of frontal and temporal lobe cortical activation in Chinese first-episode medication-naïve and recurrent depression during a verbal fluency task

Background

Functional near-infrared spectroscopy (fNIRS) identifies neurophysiological differences between psychiatric disorders by assessing cortical hemodynamic function. Few trials have studied differences in brain functional activity between first-episode medication-naïve depression patients (FMD) and recurrent major depression (RMD). We aimed to determine the differences between FMD and RMD in oxygenated hemoglobin concentration ([oxy-Hb]), and to investigate the correlation between frontotemporal cortex activation and clinical symptoms.

Methods

We recruited 40 patients with FMD, 53 with RMD, and 38 healthy controls (HCs) from May 2021 to April 2022. Symptom severity was assessed with the 24-item Hamilton Depression Rating Scale (HAM-D) and the Hamilton Anxiety Rating Scale (HAM-A). A 52-channel fNIRS measured changes in [oxy-Hb] during VFT performance.

Results

Both patient groups performed poorly during the VFT task compared with HC (FDR p < 0.05), but there was no significant difference between the two patient groups. Analysis of variance showed that mean [oxy-Hb] activation was lower in both the frontal and temporal lobes in the MDD group compared with HCs (FDR p < 0.05). Additionally, patients with RMD had a significantly lower hemodynamic response in the right dorsolateral prefrontal cortex (DLPFC) and dorsal frontal pole cortex (DFPC) than patients with FMD (FDR p < 0.05). No significant correlation was found between changes in mean [oxy-Hb] and either medical history or clinical symptoms (FDR p < 0.05).

Conclusion

The presence of different neurofunctional activity in some of the same brain regions in FMD and RMD patients implied a link between the level of complexity activation in frontal regions and the stage of MDD. Cognitive impairment may already be present at the beginning of an MDD episode.

Clinical trial registration

www.chictr.org.cn, identifier ChiCTR2100043432.

Functional connectivity and cognitive changes after donepezil treatment in healthy participants

RATIONALE

Donepezil is a potent, noncompetitive, reversible, clinically effective acetylcholinesterase inhibitor. The effects of this drug on healthy brains have seldom been investigated.

OBJECTIVES

The primary objective of the present study was to identify possible functional connectivity markers of the effect of donepezil in healthy young adult volunteers.

METHODS

The study had a double-blind, randomized, crossover design. 30 healthy adult volunteers underwent resting-state MRI scans during 15 days of donepezil or placebo treatment, in accordance with the design.

RESULTS

Results showed significant differences in intrinsic functional connectivity between donepezil and placebo, mainly in the right executive control network (RECN). More specifically, we found a decrease in the connectivity of the right inferior parietal node with other RECN nodes. Analysis using the cingulate cortex and parahippocampal regions as seeds also revealed complex modulation of functional connectivity in the donepezil condition.

CONCLUSIONS

In conclusion, donepezil treatment for 15 days may result in reorganization of resting-state networks, compared with placebo.

Neuroplasticity and brain reorganization associated with positive outcomes of multidisciplinary rehabilitation in progressive multiple sclerosis: A fMRI study

BACKGROUND

Multiple sclerosis (MS) is characterized by a range of symptoms, including motor, sensorimotor and cognitive impairments, that limit the quality of life. A multidisciplinary rehabilitation approach in people affected by multiple sclerosis was recently reported to improve the functional abilities of MS patients in daily activities. The purpose of the study was to assess the effect of multidisciplinary rehabilitation on the whole brain of MS patients by means of functional magnetic resonance imaging (fMRI).

METHODS

Thirty individuals affected by MS (49.9 ± 12.1 years; disease duration: 16.0 ± 8.5 years) with a medium-high severity of disease were enrolled. The fMRI examination assessed a range of action-related tasks involving passive movement, mental simulation of action and miming of action triggered by external stimuli, such as object photography. The three tasks were performed using each arm separately. The fMRI acquisitions were performed at T1 (inclusion in the study), T2 (3 months later, at the start of rehabilitation) and T3 (after 3 months of multidisciplinary rehabilitation).

RESULTS

The fMRI results revealed a significant reduction in the activity of brain areas related to task-specific networks as well as the activation of cerebral regions not usually involved in task-specific related network, such as the medial prefrontal area.

CONCLUSIONS

The effectiveness of multidisciplinary rehabilitation on activity and participation has been established in previous studies. Our study sheds new light on the effect of such treatment on brain reorganization.

Cognitive Impairments in First-Episode Drug-Naïve Versus Medicated Depressive Patients: RBANS in a Chinese Population

Cognitive deficits are a core feature of major depressive disorder (MDD). However, there are no previous studies that directly compare cognitive performance between first-episode drug-naive depressive patients (FDDP) and medicated depressive patients (MDP). Therefore, the aim of this study was to investigate whether there were the differences in cognitive functions between FDDP and MDP. Sixty-two FDDP, 111 MDP and 90 healthy controls were enrolled in a Chinese population. Cognitive functions were assessed using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). There were the differences in the RBANS total score (F = 26.55, p < 0.001), subscales of immediate memory (F = 3.95, p = 0.02), language (F = 54.11, p < 0.001) and delayed memory (F = 11.19, p = 0.001) among the three groups after controlling for gender, education, smoking and body mass index (BMI). These differences in the RBANS total score, subscales of language and delayed memory passed the Bonferroni corrections (all, p < 0.05). Compared to healthy controls, FDDP and MDP had poorer cognitive performance including the RBANS total score, and subscales of language and delayed memory (all, p < 0.05) after controlling for the variables. FDDP experienced greater language deficits than MDP (p < 0.05) after controlling for the variables. Education was correlated with the language score in FDDP (r = 0.61, p < 0.001). Multivariate regression analysis indicated that education was an independent contributor to the language score in FDDP (ß = 3.11, t = 5.48, p < 0.001). Our findings indicated that FDDP had poorer language performance than MDP. Moreover, education could influence the language performance in FDDP.

Brain functional alterations observed 4-weekly in major depressive disorder following antidepressant treatment

BACKGROUND

Major depressive disorder (MDD) is a heterogeneous condition. Identifying the brain responses to antidepressant treatment is of particular interest as these may represent potential neural networks related to treatment response, forming one aspect of the biological markers of MDD. Near-infrared spectroscopy (NIRS) is suitable for repeated measurements with short intervals because of its noninvasiveness, and can provide detailed time courses of functional alterations in prefrontal regions.

METHODS

We conducted a 12-week longitudinal study to explore prefrontal hemodynamic changes at 4-week intervals following sertraline treatment in 11 medication-naïve participants with MDD using 52-channel NIRS.

RESULTS

While all participants achieved remission after treatment, intra-class correlation coefficient of oxygenated hemoglobin [oxy-Hb] values throughout the 12-week observation was moderate at the spatially and temporally contiguous cluster located in the left inferior frontal and temporal gyri. There was a significant negative correlation between mean [oxy-Hb] values in the significant cluster at 4 weeks and changes in Hamilton Rating Scale for Depression total score from 4 to 8 weeks (r = -0.73, P = 0.011) and from 4 to 12 weeks (r = -0.63, P = 0.039).

LIMITATIONS

Without healthy controls for comparison, we were unable to fully evaluate whether improvement of [oxy-Hb] activations after treatment in MDD reached normal levels or not.

CONCLUSION

Our NIRS findings of detailed prefrontal hemodynamic alterations over short interval observations such as 4 weeks may have revealed potential trait marker for MDD and biological maker for predicting clinical response to sertraline treatment in MDD.

Pharmacologic approaches to cerebral aging and neuroplasticity: insights from the stroke model

Brain plasticity is an intrinsic characteristic of the nervous system that allows continuous remodeling of brain functions in pathophysiological conditions. Although normal aging is associated with morphological modifications and decline of cerebral functions, brain plasticity is at least partially preserved in elderly individuals. A growing body of evidence supports the notion that cognitive enrichment and aerobic training induce a dynamic reorganization of higher cerebral functions, thereby helping to maintain operational skills in the elderly and reducing the incidence of dementia. The stroke model clearly shows that spontaneous brain plasticity exists after a lesion, even in old patients, and that it can be modulated through external factors like rehabilitation and drugs. Whether drugs can be used with the aim of modulating the effects of physical training or cognitive stimulation in healthy aged people has not been addressed until now. The risk:benefit ratio will be the key question with regard to the ethical aspect of this challenge. We review in this article the main aspects of human brain plasticity as shown in patients with stroke, the drug modulation of brain plasticity and its consequences on recovery, and finally we address the question of the influence of aging on brain plasticity.

Effect of levodopa on both verbal and motor representations of action in Parkinson's disease: a fMRI study

Previous studies have demonstrated that non-demented Parkinson's disease (PD) patients have a specific impairment of verb production compared with noun generation. One interpretation of this deficit suggested the influence of striato-frontal dysfunction on action-related verb processing. The aim of our study was to investigate cerebral changes after motor improvement due to dopaminergic medication on the neural circuitry supporting action representation in the brain as mediated by verb generation and motor imagery in PD patients. Functional magnetic resonance imaging on 8 PD patients in "ON" dopaminergic treatment state (DTS) and in "OFF" DTS was used to explore the brain activity during three different tasks: Object Naming (ObjN), Generation of Action Verbs (GenA) in which patients were asked to overtly say an action associated with a picture and mental simulation of action (MSoA) was investigated by asking subjects to mentally simulate an action related to a depicted object. The distribution of brain activities associated with these tasks whatever DTS was very similar to results of previous studies. The results showed that brain activity related to semantics of action is modified by dopaminergic treatment in PD patients. This cerebral reorganisation concerns mainly motor and premotor cortex suggesting an involvement of the putaminal motor loop according to the "motor" theory of verb processing.

Effects of sedative antidepressants on prefrontal cortex activity during verbal fluency task in healthy subjects: a near-infrared spectroscopy study

RATIONALE

Japanese researchers have recently conducted studies using near-infrared spectroscopy (NIRS) to help diagnose psychiatric disorders based on changes in brain activity. However, the influence of psychotropic drugs on NIRS measurements has not been clarified.

OBJECTIVE

To assess the effects of sedative antidepressants on prefrontal cortex activity in healthy subjects using NIRS in a double-blinded, placebo-controlled, crossover trial.

METHODS

Nineteen healthy males received nocturnal doses of mirtazapine 15 mg, trazodone 25 mg, or placebo for eight consecutive days in rotation, with a washout period of more than 1 week between each rotation. Subjects performed a verbal fluency task during NIRS on a total of seven occasions during the study period: more than a week prior to receiving the first dose of the first medication; and on days 2 and 9 of each rotation. The number of words correctly generated during the task (behavioral performance) was also recorded. Stanford Sleepiness Scale (SSS) scores were determined each day.

RESULTS

Mirtazapine 15 mg significantly increased oxyhemoglobin (oxy-Hb) concentration change in NIRS on day 9, compared to trazodone 25 mg and placebo. Mirtazapine 15 mg significantly increased SSS on day 2, compared to the other conditions. No significant differences in behavioral performance were observed.

CONCLUSIONS

Administration of mirtazapine for eight consecutive days affected oxy-Hb changes on NIRS. This result indicates that researchers should consider how certain types of antidepressant could influence brain function when the brain activity of patients with psychiatric disorders is assessed.

The modulation of venlafaxine on cortical activation of language area in healthy subjects with fMRI study

RATIONALE

Previous studies have shown that selective serotonin reuptake inhibitors, activators of the cortex, apparently improved language functional recovery after brain damage rather than simply affective disorders.

OBJECTIVE

Our aim was to determine whether venlafaxine (an agonist of both norepinephrine and 5-hydroxytryptamine) could modulate language cortex function.

METHODS

A double-blind, crossover, randomized design was used to compare two 7-day treatment sessions with either venlafaxine (75 mg per day) or placebo. A functional magnetic resonance imaging experiment and two language function tests were performed on eight healthy males (mean age, 28.25 ± 3.15 years) at the end of each session, i.e., study entry, after venlafaxine, and after placebo (days 0, 7, and 18). Hyperactivation (venlafaxine minus placebo >0) or hypoactivation (placebo minus venlafaxine >0) by venlaxafine was assessed on the basis of the activation-baseline contrast.

RESULTS

The naming score (P < .001) and spontaneous language fluency (P < .001) were significantly higher after venlafaxine than after placebo. Functional magnetic resonance imaging (fMRI) showed that (1) picture naming activated the left posterior gyrus frontalis medius and the bilateral fusiform gyrus and the bilateral outer occipital lobes, (2) hyperactivation was observed in the adjoining area of posterior upper Broca area and premotor area in the dominant hemisphere in venlafaxine session (after venlafaxine), (3) the hyperactivation of the left gyrus frontalis medius on fMRI and the increase in naming test score were positively correlated, and (4) by contrast, we observed hypoactivation in the temporo-parieto-occipital region in venlafaxine session (after venlafaxine). This improvement may be related to increased phonics-related output in the frontal language cortex of the dominant hemisphere.

Neuroimaging of child abuse: a critical review

Childhood maltreatment is a stressor that can lead to the development of behavior problems and affect brain structure and function. This review summarizes the current evidence for the effects of childhood maltreatment on behavior, cognition and the brain in adults and children. Neuropsychological studies suggest an association between child abuse and deficits in IQ, memory, working memory, attention, response inhibition and emotion discrimination. Structural neuroimaging studies provide evidence for deficits in brain volume, gray and white matter of several regions, most prominently the dorsolateral and ventromedial prefrontal cortex but also hippocampus, amygdala, and corpus callosum (CC). Diffusion tensor imaging (DTI) studies show evidence for deficits in structural interregional connectivity between these areas, suggesting neural network abnormalities. Functional imaging studies support this evidence by reporting atypical activation in the same brain regions during response inhibition, working memory, and emotion processing. There are, however, several limitations of the abuse research literature which are discussed, most prominently the lack of control for co-morbid psychiatric disorders, which make it difficult to disentangle which of the above effects are due to maltreatment, the associated psychiatric conditions or a combination or interaction between both. Overall, the better controlled studies that show a direct correlation between childhood abuse and brain measures suggest that the most prominent deficits associated with early childhood abuse are in the function and structure of lateral and ventromedial fronto-limbic brain areas and networks that mediate behavioral and affect control. Future, large scale multimodal neuroimaging studies in medication-naïve subjects, however, are needed that control for psychiatric co-morbidities in order to elucidate the structural and functional brain sequelae that are associated with early environmental adversity, independently of secondary co-morbid conditions.

Landmark sequencing and route knowledge: an fMRI study

INTRODUCTION

The ability to navigate in a familiar environment mainly relies on route knowledge, that is, a mental representation of relevant locations along a way, sequenced according to a navigational goal. Despite the clear ecological validity of this issue, route navigation and route knowledge have been scarcely investigated and little is known about the neural and cognitive bases of this navigational strategy. Using functional magnetic resonance imaging (fMRI) we tested the validity of the predictions based on the main cognitive models of spatial knowledge acquisition about route-based navigation.

METHODS

An order judgment task was used with two conditions (route and activity). Subjects were required to detect potential mismatches between a current sensory input and expectations deriving from route and activity knowledge.

RESULTS

A medial occipto-temporal (e.g., lingual gyrus, calcarine cortex, fusiform gyrus, parahippocampal cortex) network was found activated during the route task, whereas a temporo-parietal (temporo-parietal junction) and frontal (e.g., Broca's area) network was related to the activity task.

CONCLUSIONS

Functional data are congruent with cognitive models of route-based navigation. The route task activated areas related to both landmark identity and landmark order. Data are discussed in view of route-based navigation models.

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.

The effects of antidepressants on human brain as detected by imaging studies. Focus on major depression

Recent brain imaging studies have shed light on understanding the pathogenesis of mood disorders. Evidence of structural, chemical, and functional brain changes, particularly in prefrontal cortex, cingulate, and amygdala, has been revealed in major depressive disorder (MDD). Furthermore, imaging techniques have been applied to monitor the effects of antidepressants (ADs) both in the brains of healthy volunteers and MDD patients. Although with some discrepancies due to the differences in study designs and patient samples, imaging findings have shown that ADs, particularly those having effects on the serotonergic system, modulate the volumes, functions and biochemistry of brain structures, i.e. dorsolateral prefrontal cortex, anterior cingulate and amygdala, which have been demonstrated abnormal in MDD by earlier imaging studies. This paper reviews imaging studies conducted in MDD patients and healthy controls treated with different ADs.

The effect of selective serotonin reuptake inhibitors in healthy subjects. A systematic review

BACKGROUND

Selective serotonin reuptake inhibitors (SSRIs) show antidepressant properties in many patients with a diagnosis of depression. An understanding of the underlying mechanisms of the effect of SSRIs in healthy patients may lead to an understanding of the yet unclear pathophysiology of depression. Recent reviews of studies investigating the effect of SSRIs in healthy persons conclude that the results are inconsistent and that--in relation to a wide range of outcomes--the effect of SSRIs is limited; however, reasons for the inconsistencies are poorly studied.

AIMS AND METHODS

To investigate whether methodological artefacts can explain the diverging findings, we conducted a systematic review of all randomized multiple-dose, placebo-controlled trials on the effect of treatment by SSRI for at least a week in healthy persons published before January 2009.

RESULTS

We identified 33 trials, investigating six SSRIs and 163 outcome tests. The effect of SSRI showed divergence presumably related to methodological issues. Specifically, it is likely that the majority of studies included a mix of healthy persons with and without a family history of affective disorders. Few presented information on factors that may influence outcomes such as age, gender, family history of psychiatric disorder, drug levels and ethnicity. No study fulfilled principles of conducting and reporting randomized controlled trials, according to the CONSORT Statement guidelines.

CONCLUSIONS

It is unclear whether the effect of SSRIs in healthy persons may lead to an understanding of the pathophysiology of depression, since the present evidence is divergent and may be severely influenced by a number of methodological drawbacks.

Does neuroimaging research examining the pathophysiology of posttraumatic stress disorder require medication-free patients?

BACKGROUND

In an attempt to avoid unknown influence, most neuroimaging studies examining the pathophysiology of posttraumatic stress disorder (PTSD) exclude patients taking medications. Here we review the empirical evidence for relevant medications having a confounding effect on task performance or cerebral blood flow (CBF) in this population. The evidence for potentially confounding effects of psychotherapy in PTSD are also discussed.

METHODS

The literature that we reviewed was obtained through a PubMed search from 1980 to 2009 using the search terms posttraumatic stress disorder, PTSD, psychotropic medications, neuroimaging, functional magnetic resonance imaging, positron emission tomography, cerebral blood flow, CBF, serotonin-specific reuptake blocker, benzodiazepine, ketamine, methamphetamine, lamotrigine and atypical antipsychotic agents.

RESULTS

The empirical evidence for relevant medications having a confounding effect on task performance or CBF in relevant areas remains sparse for most psychotropic medications among patients with PTSD. However, considerable evidence is accumulating for 2 of the most commonly prescribed medication classes (serotonin-specific reuptake inhibitors and benzodiazepines) in healthy controls. Compelling data for the potentially confounding effects on brain areas relevant to PTSD for psychotherapeutic interventions are also accumulating.

CONCLUSION

Neuroimaging studies examining the pathophysiology of PTSD should ideally recruit both medicated (assuming that the medication treatment has not resulted in the remission of symptoms) and unmedicated participants, to allow the findings to be generalized with greater confidence to the entire population of patients with PTSD. More research is needed into the independent effects of medications on task performance and CBF in regions of interest in PTSD. Neuroimaging studies should also take into account whether patients are currently engaged in psychotherapeutic treatment.

Assessing human 5-HT function in vivo with pharmacoMRI

A number of novel ways of using magnetic resonance imaging (MRI) to visualise the action of drugs on animal and human brain (pharmacoMRI or phMRI) are becoming established tools in translational psychopharmacology. Using drugs with known pharmacology it is possible to investigate how neurotransmitter systems are involved in neural systems engaged by other processes, such as cognitive challenge (modulation phMRI) or to examine the acute effects of the drug itself in the brain (challenge phMRI). In this article we discuss the principles behind phMRI and review studies investigating the effect of serotonin (5-HT) manipulations. 5-HT modulation phMRI studies show the involvement of 5-HT in a broad range of neural processes ranging from motor function through 'cold' cognition, such as memory and response inhibition, to emotional processing. We highlight findings in brain areas that show some consistency or complementarity across studies, such as the ventrolateral orbitofrontal cortex where modulation by 5-HT is task-specific, and the amygdala in emotional processing where 5-HT is predominantly inhibitory. 5-HT challenge phMRI is promising but as yet few studies have been carried out. New ways of analysing phMRI data include connectivity analysis which holds the promise of going beyond identifying isolated areas of activation/modulation to understanding functional circuits and their neurochemistry. 5-HT phMRI now needs to be taken into patient populations and methods of investigating treatment effects need to be developed. If this is successful then phMRI will provide a genuinely exciting opportunity for the rapid development of better treatments for psychiatric conditions.