Lucie Bartova

Additive Gene–Environment Effects on Hippocampal Structure in Healthy Humans

Hippocampal volume loss has been related to chronic stress as well as genetic factors. Although genetic and environmental variables affecting hippocampal volume have extensively been studied and related to mental illness, limited evidence is available with respect to G × E interactions on hippocampal volume. The present MRI study investigated interaction effects on hippocampal volume between three well-studied functional genetic variants (COMT Val158Met, BDNF Val66Met, 5-HTTLPR) associated with hippocampal volume and a measure of environmental adversity (life events questionnaire) in a large sample of healthy humans (n = 153). All three variants showed significant interactions with environmental adversity with respect to hippocampal volume. Observed effects were additive by nature and driven by both recent as well as early life events. A consecutive analysis of hippocampal subfields revealed a spatially distinct profile for each genetic variant suggesting a specific role of 5-HTTLPR for the subiculum, BDNF Val66Met for CA4/dentate gyrus, and COMT Val158Met for CA2/3 volume changes. The present study underscores the importance of G × E interactions as determinants of hippocampal volume, which is crucial for the neurobiological understanding of stress-related conditions, such as mood disorders or post-traumatic stress disorder (PTSD).

The spectral diversity of resting-state fluctuations in the human brain.

In order to assess whole-brain resting-state fluctuations at a wide range of frequencies, resting-state fMRI data of 20 healthy subjects were acquired using a multiband EPI sequence with a low TR (354 ms) and compared to 20 resting-state datasets from standard, high-TR (1800 ms) EPI scans. The spatial distribution of fluctuations in various frequency ranges are analyzed along with the spectra of the time-series in voxels from different regions of interest. Functional connectivity specific to different frequency ranges (<0.1 Hz; 0.1–0.25 Hz; 0.25–0.75 Hz; 0.75–1.4 Hz) was computed for both the low-TR and (for the two lower-frequency ranges) the high-TR datasets using bandpass filters. In the low-TR data, cortical regions exhibited highest contribution of low-frequency fluctuations and the most marked low-frequency peak in the spectrum, while the time courses in subcortical grey matter regions as well as the insula were strongly contaminated by high-frequency signals. White matter and CSF regions had highest contribution of high-frequency fluctuations and a mostly flat power spectrum. In the high-TR data, the basic patterns of the low-TR data can be recognized, but the high-frequency proportions of the signal fluctuations are folded into the low frequency range, thus obfuscating the low-frequency dynamics. Regions with higher proportion of high-frequency oscillations in the low-TR data showed flatter power spectra in the high-TR data due to aliasing of the high-frequency signal components, leading to loss of specificity in the signal from these regions in high-TR data. Functional connectivity analyses showed that there are correlations between resting-state signal fluctuations of distant brain regions even at high frequencies, which can be measured using low-TR fMRI. On the other hand, in the high-TR data, loss of specificity of measured fluctuations leads to lower sensitivity in detecting functional connectivity. This underlines the advantages of low-TR EPI sequences for resting-state and potentially also task-related fMRI experiments.

Reduced default mode network suppression during a working memory task in remitted major depression

Insufficient default mode network (DMN) suppression was linked to increased rumination in symptomatic Major Depressive Disorder (MDD). Since rumination is known to predict relapse and a more severe course of MDD, we hypothesized that similar DMN alterations might also exist during full remission of MDD (rMDD), a condition known to be associated with increased relapse rates specifically in patients with adolescent onset. Within a cross-sectional functional magnetic resonance imaging study activation and functional connectivity (FC) were investigated in 120 adults comprising 78 drug-free rMDD patients with adolescent- (n = 42) and adult-onset (n = 36) as well as 42 healthy controls (HC), while performing the n-back task. Compared to HC, rMDD patients showed diminished DMN deactivation with strongest differences in the anterior-medial prefrontal cortex (amPFC), which was further linked to increased rumination response style. On a brain systems level, rMDD patients showed an increased FC between the amPFC and the dorsolateral prefrontal cortex, which constitutes a key region of the antagonistic working-memory network. Both whole-brain analyses revealed significant differences between adolescent-onset rMDD patients and HC, while adult-onset rMDD patients showed no significant effects. Results of this study demonstrate that reduced DMN suppression exists even after full recovery of depressive symptoms, which appears to be specifically pronounced in adolescent-onset MDD patients. Our results encourage the investigation of DMN suppression as a putative predictor of relapse in clinical trials, which might eventually lead to important implications for antidepressant maintenance treatment.

Is there a personalized medicine for mood disorders

Major Depressive Disorder (MDD) and antidepressant therapy response are largely based on behavioral criteria, which are known to correlate at best modestly with biological measures. Therefore, it is not surprising that the search for peripheral biological markers (biomarkers) being assessed in distant biological systems such as body fluids has not yet resulted in clinically convincing measures for MDD diagnostics or treatment evaluation. Imaging genetics studies, however, have been successful in the search for intermediate imaging phenotypes of MDD and treatment response that are directly related to the neurobiological underpinnings of MDD, but are not suitable for a broad clinical use today. Hence, we argue that intermediate phenotypes derived from imaging genetics studies should be utilized as substitutes of behaviorally assessed psychiatric diagnoses or therapy response in the search for easily accessible peripheral biomarkers. This article will further cover the current state of peripheral and neural biomarker research.

Administration of ketamine for unipolar and bipolar depression

Abstract Objective: Clinical trials demonstrated that ketamine exhibits rapid antidepressant efficacy when administered in subanaesthetic dosages. We reviewed currently available literature investigating efficacy, response rates and safety profile. Methods: Twelve studies investigating unipolar, seven on bipolar depression were included after search in medline, scopus and web of science. Results: Randomized, placebo-controlled or open-label trials reported antidepressant response rates after 24 h on primary outcome measures at 61%. The average reduction of Hamilton Depression Rating Scale (HAM-D) was 10.9 points, Beck Depression Inventory (BDI) 15.7 points and Montgomery-Asberg Depression Rating Scale (MADRS) 20.8 points. Ketamine was always superior to placebo. Most common side effects were dizziness, blurred vision, restlessness, nausea/vomiting and headache, which were all reversible. Relapse rates ranged between 60% and 92%. To provide best practice-based information to patients, a consent-form for application and modification in local language is included. Conclusions: Ketamine constitutes a novel, rapid and efficacious treatment option for patients suffering from treatment resistant depression and exhibits rapid and significant anti-suicidal effects. New administration routes might serve as alternative to intravenous regimes for potential usage in outpatient settings. However, long-term side effects are not known and short duration of antidepressant response need ways to prolong ketamine’s efficacy.

Platelet Serotonin Transporter Function Predicts Default-Mode Network Activity

Background The serotonin transporter (5-HTT) is abundantly expressed in humans by the serotonin transporter gene SLC6A4 and removes serotonin (5-HT) from extracellular space. A blood-brain relationship between platelet and synaptosomal 5-HT reuptake has been suggested, but it is unknown today, if platelet 5-HT uptake can predict neural activation of human brain networks that are known to be under serotonergic influence. Methods A functional magnetic resonance study was performed in 48 healthy subjects and maximal 5-HT uptake velocity (Vmax) was assessed in blood platelets. We used a mixed-effects multilevel analysis technique (MEMA) to test for linear relationships between whole-brain, blood-oxygen-level dependent (BOLD) activity and platelet Vmax. Results The present study demonstrates that increases in platelet Vmax significantly predict default-mode network (DMN) suppression in healthy subjects independent of genetic variation within SLC6A4. Furthermore, functional connectivity analyses indicate that platelet Vmax is related to global DMN activation and not intrinsic DMN connectivity. Conclusion This study provides evidence that platelet Vmax predicts global DMN activation changes in healthy subjects. Given previous reports on platelet-synaptosomal Vmax coupling, results further suggest an important role of neuronal 5-HT reuptake in DMN regulation.

Pharmacological treatment strategies in unipolar depression in European tertiary psychiatric treatment centers – A pharmacoepidemiological cross-sectional multicenter study

This multicenter, cross-sectional study with retrospective assessment of treatment response evaluated the current prescription trends and pharmacological treatment strategies applied in European university/academic psychiatric centers in unipolar depression. Altogether, 1181 adult in- and outpatients with major depressive disorder (MDD) were enrolled in 9 academic sites in 8 European countries. Socio-demographic, clinical, and medication information were retrieved and the present symptom severity was assessed by the Montgomery and Åsberg Depression Rating Scale (MADRS). The symptom improvement during the current MDD episode was covered by retrospective MADRS measurements. Beyond descriptive statistics, analyses of variance (ANOVA) and Spearman correlation analyses were accomplished to determine the influence of symptom severity and treatment response on the prescription patterns. 53.4% of all MDD patients received a selective serotonin reuptake inhibitor (SSRI) and 23.6% a serotonin-norepinephrine reuptake inhibitor (SNRI) as first-line treatment. The majority of participants (59.4%) were treated with polypharmaceutical strategies (median: 2 psychiatric compounds per patient) and for the number of individual drugs we found a significant correlation with the current MADRS total score and the MADRS total score change during the present depressive episode. Benzodiazepines (33.2% of patients), antidepressants (29.0%), antipsychotics (24.2%), and mood stabilizers (10.1%) were the most frequently prescribed adjunctive agents. There were no significant differences between the different psychopharmacological classes used as augmentors in terms of symptom severity and treatment response. In summary, this international cross-sectional study revealed the widespread use of polypharmaceutical treatment strategies in European tertiary psychiatric treatment centers for the management of MDD.

Bipolar II disorder as a risk factor for postpartum depression

OBJECTIVES There is evidence for a bipolar diathesis in postpartum depression (PPD) and women presenting with a first PPD frequently receive a diagnosis of bipolar type II disorder (BD-II). However formal evidence for an association between BD-II and PPD has not yet been reported. In the present study we tested a potential association between BD-II and PPD. METHODS Parous women with a diagnosis of bipolar type I disorder (BD-I) (n=93), BD-II (n=36) or major depressive disorder (MDD) (n=444) were considered in the present study. All women were retrospectively evaluated for history of PPD (DSM-IV criteria) and other clinical and socio-demographic features. RESULTS Women with a history of PDD (n=139, 24%) were younger, younger at illness onset and had more family history for BD compared to women without history of PPD (n=436, 75.9%). Half of BD-II women reported PPD (50%), compared to less than one-third of BD-I and MDD women (respectively 27.5% and 21.6%) (p=0.004). LIMITATIONS Limitations include the retrospective assessment of PPD and no available data about the timing of postpartum episodes, illness onset or psychiatric care before or after childbirth, and the number of postpartum episodes. CONCLUSIONS BD-II may confer a remarkable risk for PPD, which may be even higher than that of women affected by BD-I disorder. Careful monitoring of BD-II women during the pregnancy and postpartum period, as well as assessment of bipolar features in women with a PPD without a current diagnosis of BD are recommended.

Making Sense of: Sensitization in Schizophrenia.

Abstract Sensitization is defined as a process whereby repeated intermittent exposure to a given stimulus results in an enhanced response at subsequent exposures. Next to robust findings of an increased dopamine synthesis capacity in schizophrenia, empirical data and neuroimaging studies support the notion that the mesolimbic dopamine system of patients with schizophrenia is more reactive compared with healthy controls. These studies led to the conceptualization of schizophrenia as a state of endogenous sensitization, as stronger behavioral response and increased dopamine release after amphetamine administration or exposure to stress have been observed in patients with schizophrenia. These findings have also been integrated into the neurodevelopmental model of the disorder, which assumes that vulnerable neuronal circuits undergo progressive changes during puberty and young adulthood that lead to manifest psychosis. Rodent and human studies have made an attempt to identify the exact mechanisms of sensitization of the dopaminergic system and its association with psychosis. Doing so, several epigenetic and molecular alterations associated with dopamine release, neuroplasticity, and cellular energy metabolism have been discovered. Future research aims at targeting these key proteins associated with sensitization in schizophrenia to enhance the knowledge of the pathophysiology of the illness and pave the way for an improved treatment or even prevention of this severe psychiatric disorder.

Combination of intravenous S-ketamine and oral tranylcypromine in treatment-resistant depression: A report of two cases.

Ketamine, a rapid-acting antidepressant and anti-suicidal agent, is thought to increase brain monoamine levels by enhancing monoamine release or inhibiting presynaptic monoamine-reuptake. Here we present two female inpatients suffering from treatment-resistant depression with recurrent severe suicidal crises receiving a combination of intravenous S-ketamine and oral tranylcypromine, which is a well-known irreversible monoamine oxidase (MAO) inhibitor. Since inhibition of monoamine-reuptake with concurrent blockade of MAO might trigger sympathomimetic crisis, this combination is considered hazardous. Nonetheless, cardiovascular parameters remained stable in both patients, while good anti-suicidal effects were observed. Hence, we put serious doubt on whether monoamine-reuptake inhibition is a relevant pharmacological effect of ketamine in humans.