Deep phenotyping as a contribution to personalized depression therapy: the GEParD and DaCFail protocols.

Depressive patients suffer from a complex of symptoms of varying intensity compromising their mood, emotions, self-concept, neurocognition, and somatic function. Due to a mosaic of aetiologies involved in developing depression, such as somatic, neurobiological, (epi-)genetic factors, or adverse life events, patients often experience recurrent depressive episodes. About 20-30% of these patients develop difficult-to-treat depression. Here, we describe the design of the GEParD (Genetics and Epigenetics of Pharmaco- and Psychotherapy in acute and recurrent Depression) cohort and the DaCFail (Depression-associated Cardiac Failure) case-control protocol. Both protocols intended to investigate the incremental utility of multimodal biomarkers including cardiovascular and (epi-)genetic markers, functional brain and heart imaging when evaluating the response to antidepressive therapy using comprehensive psychometry. From 2012 to 2020, 346 depressed patients (mean age 45 years) were recruited to the prospective, observational GEParD cohort protocol. Between 2016 and 2020, the DaCFail case-control protocol was initiated integrating four study subgroups to focus on heart-brain interactions and stress systems in patients > 50 years with depression and heart failure, respectively. For DaCFail, 120 depressed patients (mean age 60 years, group 1 + 2), of which 115 also completed GEParD, and 95 non-depressed controls (mean age 66 years) were recruited. The latter comprised 47 patients with heart failure (group 3) and 48 healthy subjects (group 4) of a population-based control group derived from the Characteristics and Course of Heart Failure Stages A-B and Determinants of Progression (STAAB) cohort study. Our hypothesis-driven, exploratory study design may serve as an exemplary roadmap for a standardized, reproducible investigation of personalized antidepressant therapy in an inpatient setting with focus on heart comorbidities in future multicentre studies.

Effects of Anxious Depression on Antidepressant Treatment Response.

Anxious depression represents a subtype of major depressive disorder and is associated with increased suicidality, severity, chronicity and lower treatment response. Only a few studies have investigated the differences between anxious depressed (aMDD) and non-anxious depressed (naMDD) patients regarding treatment dosage, serum-concentration and drug-specific treatment response. In our naturalistic and prospective study, we investigated whether the effectiveness of therapy including antidepressants (SSRI, SNRI, NaSSA, tricyclics and combinations) in aMDD patients differs significantly from that in naMDD patients. In a sample of 346 patients, we calculated the anxiety somatization factor (ASF) and defined treatment response as a reduction (≥50%) in the Hamilton Depression Rating Scale (HDRS)-21 score after 7 weeks of pharmacological treatment. We did not observe an association between therapy response and the baseline ASF-scores, or differences in therapy outcomes between aMDD and naMDD patients. However, non-responders had higher ASF-scores, and at week 7 aMDD patients displayed a worse therapy outcome than naMDD patients. In subgroup analyses for different antidepressant drugs, venlafaxine-treated aMDD patients showed a significantly worse outcome at week 7. Future prospective, randomized-controlled studies should address the question of a worse therapy outcome in aMDD patients for different psychopharmaceuticals individually.

Effects of Pharmacokinetic Gene Variation on Therapeutic Drug Levels and Antidepressant Treatment Response.

INTRODUCTION: Pharmacogenetic testing is proposed to minimize adverse effects when considered in combination with pharmacological knowledge of the drug. As yet, limited studies in clinical settings have investigated the predictive value of pharmacokinetic (pk) gene variation on therapeutic drug levels as a probable mechanism of adverse effects, nor considered the combined effect of pk gene variation and drug level on antidepressant treatment response. METHODS: Two depression cohorts were investigated for the relationship between pk gene variation and antidepressant serum concentrations of amitriptyline, venlafaxine, mirtazapine and quetiapine, as well as treatment response. For the analysis, 519 patients (49% females; 46.6±14.1 years) were included. RESULTS: Serum concentration of amitriptyline was associated with CYP2D6 (higher concentrations in poor metabolizers compared to normal metabolizers), of venlafaxine with CYP2C19 (higher concentrations in intermediate metabolizers compared to rapid/ultrarapid metabolizers) and CYP2D6 (lower metabolite-to-parent ratio in poor compared to intermediate and normal metabolizers, and intermediate compared to normal and ultrarapid metabolizers). Pk gene variation did not affect treatment response. DISCUSSION: The present data support previous recommendations to reduce starting doses of amitriptyline and to guide dose-adjustments via therapeutic drug monitoring in CYP2D6 poor metabolizers. In addition, we propose including CYP2C19 in routine testing in venlafaxine-treated patients to improve therapy by raising awareness of the risk of low serum concentrations in CYP2C19 rapid/ultrarapid metabolizers. In summary, pk gene variation can predict serum concentrations, and thus the combination of pharmacogenetic testing and therapeutic drug monitoring is a useful tool in a personalized therapy approach for depression.

Stress impairs response to antidepressants via HPA axis and immune system activation.

Childhood trauma as well as severe events occurring later in life have been associated with the development of major depressive disorder (MDD). However, the interaction of early and later occurring adverse events in patients with MDD is understudied. This study aims to disentangle this interaction by investigating the effects on two of the main stress-response systems of the body, the hypothalamic-pituitaryadrenal (HPA-) axis and the immune system in depressed patients. The function of the HPA-axis was assessed by measuring FKBP5, SGK1 and NR3C1 mRNA-expression in peripheral blood after an in vivo glucocorticoid receptor (GR) challenge with 1.5 mg dexamethasone in 150 depressed in-patients (47.4% females). Childhood trauma was evaluated using the Childhood Trauma Questionnaire (CTQ), severe life events occurring one year prior to hospital admission were assessed with the List of Threatening Experiences (LTE). Multiple childhood traumata, i.e. ≥ 3, were present in 68 (45.5%) patients, 59 (39.3%) experienced ≥ 3 severe recent life events. The history of ≥ 3 severe recent life events was associated with an impaired GR-induction of SGK1 (F = 10.455; df = 1; p = 0.002) and FKBP5 mRNA expression (F = 8.720; df = 1; p = 0.004), and with elevated measures of the immune system such as CRP and lymphocyte count. In addition, severe recent life events were associated with a substantially impaired treatment response to antidepressants (F = 7.456; df = 1; p = 0.008). These effects could not be observed in relation to childhood trauma. Severe life events occurring prior to MDD development substantially impaired the stress-response systems and the response to treatment with antidepressants. This finding may indicate the need to employ additional treatment options such as psychotherapy right at the beginning of treatment or immune-modulating approaches.

Nortriptyline serum concentration as a predictor for cardiac risk in amitriptyline-treated patients.

PURPOSE: Tricyclic antidepressants have been shown to affect electrocardiogram (ECG) parameters, but there is limited evidence in relation to the serum concentrations. Therefore, we aimed to evaluate a prediction of cardiac risk in amitriptyline- and doxepin-treated patients by serum concentrations. PATIENTS AND METHODS: The association between serum concentrations of amitriptyline (n = 100) and doxepin (n = 71) and ECG parameters was retrospectively examined using linear regression analysis. Mann-Whitney U tests were applied to evaluate differences in QTc intervals in patients with serum concentrations above and below the upper limit of the therapeutic reference range, as well as the alert level of each target drug. RESULTS: The sum serum concentration of amitriptyline and the nortriptyline serum concentration were significantly associated with an increased PQ interval (p = 0.020, p = 0.007), as well as with increased QTcB (p = 0.012, p < 0.001) and QTcF intervals (p = 0.025, p < 0.001). The nortriptyline concentration was significantly associated with the QRS interval (p = 0.003). In patients with active moiety concentrations above the alert level (300 ng/ml) and nortriptyline concentrations above the reference range (170 ng/ml), the QTcB interval was significantly prolonged (p = 0.032, p = 0.007). No significant association with any ECG parameter was detected for doxepin serum concentrations. CONCLUSION: The effect of amitriptyline on ECG parameters may be explained by nortriptyline alone. Accordingly, with increasing nortriptyline concentrations, the potential risk for an atrioventricular block, a bundle branch block, and prolongation of QTc interval may increase significantly.

Drug-Drug Interactions Between Lithium and Cardiovascular as Well as Anti-Inflammatory Drugs.

INTRODUCTION: Lithium is the gold standard in treating bipolar affective disorders. As patients become increasingly older, drug-drug interactions leading to decreased excretion of lithium represent a key issue in lithium safety. As no study considered the effect of comedications on lithium serum concentration in combination, we aimed to quantify the impact of drugs affecting renal blood flow and function and thus potentially interacting drugs (diuretics, ACE inhibitors, AT1 antagonists, and non-steroidal anti-inflammatory drugs) on lithium serum levels in addition to age, sex, and sodium and potassium serum levels as well as renal function. METHODS: Retrospective data of lithium serum levels were analyzed in 501 psychiatric inpatients (2008-2015) by means of linear regression modelling. RESULTS: The number of potentially interacting drugs was significantly associated with increasing serum levels of lithium in addition to the established factors of age, renal function, and sodium concentration. Additionally, absolute lithium levels were dependent on sex, with higher values in females. However, only NSAIDs were identified to increase lithium levels independently. DISCUSSION: Routine clinical practice needs to focus on drugs affecting renal blood flow and function, especially on NSAIDs as over-the-counter medication that may lead to an increase in lithium serum concentration. To prevent intoxications, clinicians should carefully monitor the comedications, and they should inform patients about possible intoxications due to NSAIDs.

Covariation bias in depression - a predictor of treatment response?

Covariation bias, defined as an overestimation of the relationship between fear-relevant stimuli and aversive consequences, is a well-investigated cognitive bias in anxiety disorders. As patients with affective disorders also show biased information processing, the aim of the present study was to investigate whether depressed patients also display a covariation bias between negative stimuli and aversive consequences. Covariation estimates of 62 inpatients with a current severe depressive episode were assessed at admission (n = 31) or after 6 weeks of treatment (n = 31) and were compared in a between-group design with 31 age- and sex-matched healthy controls. All participants showed a covariation bias for the relationship between negative stimuli and aversive consequences. Moreover, covariation bias at admission was significantly associated with various clinician- and self-reported dimensional measures of treatment response assessed 6 weeks later (Global Assessment of Functioning, Clinical Global Impression Scale, and Beck Depression Inventory), i.e., patients with a stronger bias showed greater impairment after 6 weeks of treatment. Categorical analyses revealed that overall, treatment non-responders-but not responders-were characterized by a covariation bias. The naturalistic study design without standardized pharmacological and psychotherapeutic treatments is a central limitation. We conclude that the covariation bias may constitute a possible marker in the field of emotional information processing in the search for effective predictors of therapy outcome.

Comedication of Valproic Acid Is Associated With Increased Metabolism of Clozapine.

OBJECTIVES: Valproic acid and clozapine are drugs commonly used in the treatment of schizophrenic and schizoaffective disorders. Pharmacokinetic interactions of valproic acid with several drugs are well known, yet results concerning the interaction with clozapine are inconsistent. METHODS: Steady-state dose-corrected serum concentrations of clozapine and its main metabolite norclozapine were retrospectively analyzed in 45 patients receiving both clozapine and valproic acid. Controls were matched for sex, age, smoking, comedication, and inflammatory response. RESULTS: The group receiving comedication with valproic acid showed significantly lower median dose-corrected serum concentrations of norclozapine (0.44 [0.27-0.58] (ng/mL)/(mg/d) vs 0.78 [0.60-1.07] (ng/mL)/(mg/d)) as well as metabolite to parent compound ratios (0.40 [0.36-0.47] vs 0.71 [0.58-0.84]) by approximately 44%. Dose-corrected serum concentrations of clozapine were not significantly lower. The effect of valproic acid was independent of sex and smoking. CONCLUSIONS: Comedication with valproic acid accelerated metabolism of clozapine with predominant effects on the degradation of norclozapine. Therapeutic drug monitoring should be applied to guide individual patient responses upon initiation of comedication.

Rsk2 Knockout Affects Emotional Behavior in the IntelliCage.

Ribosomal s6 kinase 2 is a growth factor activated serine/threonine kinase and member of the ERK signaling pathway. Mutations in the Rsk2 gene cause Coffin-Lowry syndrome, a rare syndromic form of intellectual disability. The Rsk2 KO mouse model was shown to have learning and memory defects. We focused on the investigation of the emotional behavioral phenotype of Rsk2 KO mice mainly in the IntelliCage. They exhibited an anti-depressive, sucrose reward seeking phenotype and showed reduced anxiety. Spontaneous activity was increased in some conventional tests. However, KO mice did not show defects in place learning, working memory and motor impulsivity. In addition, we found changes of the monoaminergic system in HPLC and qRT-PCR experiments. Taken together, RSK2 not only plays a role in cognitive processes but also in emotional and reward-related behaviors.

Near-infrared spectroscopy (NIRS) and vagus somatosensory evoked potentials (VSEP) in the early diagnosis of Alzheimer's disease: rationale, design, methods, and first baseline data of the Vogel study.

Functional near-infrared spectroscopy (fNIRS) and vagus somatosensory evoked potentials (VSEP) show deviant patterns in subjects with Alzheimer's disease (AD) compared to healthy controls. We now aimed at testing the predictive value of these methods in the early diagnosis of AD. The Vogel study is a prospective, observational, long-term follow-up study with three time points of investigation within 6 years. Residents of the city of Würzburg born between 1936 and 1941 were recruited. Every participant underwent physical, psychiatric, and laboratory examinations, and performed an intense neuropsychological testing as well as VSEP and NIRS according to the published procedures. 604 subjects were included. Mean age of the participants was 73.9 ± 1.55 years. The most frequent pathological physical and laboratory examination results were observed for blood pressure (62%), body weight (54%), HbA1c (16%), cholesterol (42%), and homocysteine (69%). Comprehensive analysis of cognitive testing showed mild cognitive impairment (MCI) in 12.3% of the patients. Concurrent major depression was found in 6.6% of the patients. We observed a high rate of MCI and somatic comorbidity in our cohort. The high rate of vascular risk factors and depressive symptoms, all of which are known risk factors of AD, is consistent with the notion that there are multiple options to prevent or postpone the onset of AD in a geriatric population like the one of the Vogel studies.

Heterogeneity and individuality: microRNAs in mental disorders.

MicroRNAs are about 22 nucleotide long single-stranded RNA molecules, negatively regulating gene expression of a single gene or a gene network. In neural tissues, they have been implicated in developmental and neuroplasticity-related processes, such as neurogenesis, differentiation, apoptosis and long-term potentiation. Their molecular mode of action is reminiscent of findings of genome-wide association studies in mental disorders, unable to attribute the risk of disease to a specific gene, but rather to multiple genes, gene-networks and gene-environment interaction. As such, microRNAs are an attractive target for research. Here, we review clinical studies conducted in humans on microRNAs in mental disorders with a particular focus on schizophrenia, bipolar disorder, major depressive disorder and anxiety disorders. The majority of clinical studies have focused on schizophrenia. The most robust finding has been reported for rs1625579 located in MIR137HG, which was associated with schizophrenia on a genome-wide level. Concerning bipolar disorder, major depression and anxiety disorders, promising results have been published, but only a considerably smaller number of clinical studies is available and genome-wide association studies did not suggest a direct link to microRNAs so far. Expression of microRNAs as biomarkers of mental disorders and treatment response is currently emerging with preliminary results. Larger-scaled genetic and functional studies along with translational research are needed to enhance our understanding of microRNAs in mental disorders. These studies will aid in disentangling the complex genetic nature of these disorders and possibly contribute to the development of novel, individualized diagnostic and therapeutic approaches.

MicroRNA hsa-miR-4717-5p regulates RGS2 and may be a risk factor for anxiety-related traits.

Regulator of G-protein Signaling 2 (RGS2) is a key regulator of G-protein-coupled signaling pathways involved in fear and anxiety. Data from rodent models and genetic analysis of anxiety-related traits and disorders in humans suggest down-regulation of RGS2 expression to be a risk factor for anxiety. Here we investigated, whether genetic variation in microRNAs mediating posttranscriptional down-regulation of RGS2 may be a risk factor for anxiety as well. 75 microRNAs predicted to regulate RGS2 were identified by four bioinformatic algorithms and validated experimentally by luciferase reporter gene assays. Specificity was confirmed for six microRNAs (hsa-miR-1271-5p, hsa-miR-22-3p, hsa-miR-3591-3p, hsa-miR-377-3p, hsa-miR-4717-5p, hsa-miR-96-5p) by disrupting their seed sequence at the 3' untranslated region of RGS2. Hsa-miR-4717-5p showed the most robust effect on RGS2 and regulated two other candidate genes of anxiety disorders (CNR1 and IKBKE) as well. Two SNPs (rs150925, rs161427) within and 1,000 bp upstream of the hostgene of hsa-miR-4717-5p (MIR4717) show a minor allele frequency greater than 0.05. Both were in high linkage disequilibrium (r(2) = 1, D' = 1) and both major (G) alleles showed a trend for association with panic disorder with comorbid agoraphobia in one of two patient/control samples (combined n(patients) = 497). Dimensional anxiety traits, as described by Anxiety Sensitivity Index (ASI) and Agoraphobic Cognitions Questionnaire (ACQ) were significantly higher among carriers of both major (G) alleles in a combined patient/control sample (n(combined) = 831). Taken together, data indicate that MIR4717 regulates human RGS2 and contributes to the genetic risk towards anxiety-related traits.

[Modification of perioperative psychiatric drug therapy]. / Perioperative Modifikation der psychiatrischen Dauermedikation - Wann sollte umgestellt oder pausiert werden?

Apart from cardiovascular, pulmonary and metabolic drugs, many patients scheduled for surgery are taking antidepressive or antipsychotic drugs. Some of these psychiatric drugs may interfere with anesthetics. The anesthesiologist has to decide whether or not to continue the psychiatric medication during the perioperative period. Since the discontinuation of psychiatric drugs may lead to withdrawal syndromes, the decision should be made in accordance with the attending psychiatrist. Should the discontinuation of any psychiatric drug be recommended, it may be prudent to involve the attending surgeon in order to postpone the procedure, since the modification of psychiatric drugs may take several days.Prospective randomized data about the perioperative modification of psychiatric drugs are scarce. Thus, recommendations in this regard must rely on physiological and pharmacological principles, case reports and published expert opinions. In this article we use the available data to answer the question of a journal reader regarding the perioperative modification of Opipramol therapy for a 59-year-old patient scheduled for elective shoulder surgery.

Proteolytic Cleavage of the Extracellular Domain Affects Signaling of Parathyroid Hormone 1 Receptor.

Parathyroid hormone 1 receptor (PTH1R) is a member of the class B family of G protein-coupled receptors, which are characterized by a large extracellular domain required for ligand binding. We have previously shown that the extracellular domain of PTH1R is subject to metalloproteinase cleavage in vivo that is regulated by ligand-induced receptor trafficking and leads to impaired stability of PTH1R. In this work, we localize the cleavage site in the first loop of the extracellular domain using amino-terminal protein sequencing of purified receptor and by mutagenesis studies. We further show, that a receptor mutant not susceptible to proteolytic cleavage exhibits reduced signaling to Gs and increased activation of Gq compared to wild-type PTH1R. These findings indicate that the extracellular domain modulates PTH1R signaling specificity, and that its cleavage affects receptor signaling.

G proteins in reverse mode: receptor-mediated GTP release inhibits G protein and effector function.

Active G protein-coupled receptors activate heterotrimeric Galphabetagamma proteins by catalyzing the exchange of GDP by GTP at the Galpha subunit. A paradoxical attenuation of G protein-activated inwardly rectifying potassium channels (GIRK) upon stimulation of native cells with high concentrations of agonist is known. However, a deactivation of activated G proteins by active receptors has not been experimentally studied in intact cells. We monitored GIRK currents and G(o) protein activation by means of fluorescence resonance energy transfer (FRET) in parallel. The results suggested that GIRK currents were paradoxically attenuated due to an inactivation of G(o) proteins by active alpha(2A)-adrenergic receptors. To study the mechanisms, G protein activation and receptor-G protein interactions were analyzed as a function of nucleotide type and nucleotide concentrations by means of FRET, while controlling intracellular nucleotides upon permeabilization of the cell membrane. Results suggested a receptor-catalyzed dissociation of GTP from activated heterotrimeric Galphabetagamma. Consequently, nucleotide-free G proteins were sequestrated in heterotrimeric conformation at the active receptor, thus attenuating downstream signaling in an agonist-dependent manner.

A fluorescence resonance energy transfer-based M2 muscarinic receptor sensor reveals rapid kinetics of allosteric modulation.

Allosteric modulators have been identified for several G protein-coupled receptors, most notably muscarinic receptors. To study their mechanism of action, we made use of a recently developed technique to generate fluorescence resonance energy transfer (FRET)-based sensors to monitor G protein-coupled receptor activation. Cyan fluorescent protein was fused to the C terminus of the M(2) muscarinic receptor, and a specific binding sequence for the small fluorescent compound fluorescein arsenical hairpin binder, FlAsH, was inserted into the third intracellular loop; the latter site was labeled in intact cells by incubation with FlAsH. We then measured FRET between the donor cyan fluorescent protein and the acceptor FlAsH in intact cells and monitored its changes in real time. Agonists such as acetylcholine and carbachol induced rapid changes in FRET, indicative of agonist-induced conformational changes. Removal of the agonists or addition of an antagonist caused a reversal of this signal with rate constants between 400 and 1100 ms. The allosteric ligands gallamine and dimethyl-W84 caused no changes in FRET when given alone, but increased FRET when given in the presence of an agonist, compatible with an inactivation of the receptors. The kinetics of these effects were very rapid, with rate constants of 80-100 ms and approximately 200 ms for saturating concentrations of gallamine and dimethyl-W84, respectively. Because these speeds are significantly faster than the responses to antagonists, these data indicate that gallamine and dimethyl-W84 are allosteric ligands and actively induce a conformation of the M(2) receptor with a reduced affinity for its agonists.

Antipsychotics in routine treatment are minor contributors to QT prolongation compared to genetics and age.

BACKGROUND: Drug-induced prolongation of cardiac repolarization limits the treatment with many psychotropic drugs. Recently, the contribution of polygenic variation to the individual duration of the QT interval was identified. AIMS: To explore the interaction between antipsychotic drugs and the individual polygenic influence on the QT interval. METHODS: Retrospective analysis of clinical and genotype data of 804 psychiatric inpatients diagnosed with a psychotic disorder. The individual polygenic influence on the QT interval was calculated according to the method of Arking et al. RESULTS: Linear regression modelling showed a significant association of the individual polygenic QT interval score (ßstd = 0.176, p < 0.001) and age (ßstd = 0.139, p < 0.001) with the QTc interval corrected according to Fridericia's formula. Sex showed a nominal trend towards significance (ßstd = 0.064, p = 0.064). No association was observed for the number of QT prolonging drugs according to AZCERT taken. Subsample analysis (n = 588) showed a significant association of potassium serum concentrations with the QTc interval (ßstd = -0.104, p = 0.010). Haloperidol serum concentrations were associated with the QTc interval only in single medication analysis (n = 26, ßstd = 0.101, p = 0.004), but not in multivariate regression analysis. No association was observed for aripiprazole, clozapine, quetiapine and perazine, while olanzapine and the sum of risperidone and its metabolite showed a negative association. CONCLUSIONS: Individual genetic factors and age are main determinants of the QT interval. Antipsychotic drug serum concentrations within the therapeutic range contribute to QTc prolongation on an individual level.

5-HTT Deficiency in Male Mice Affects Healing and Behavior after Myocardial Infarction.

Anxiety disorders and depression are common comorbidities in cardiac patients. Mice lacking the serotonin transporter (5-HTT) exhibit increased anxiety-like behavior. However, the role of 5-HTT deficiency on cardiac aging, and on healing and remodeling processes after myocardial infarction (MI), remains unclear. Cardiological evaluation of experimentally naïve male mice revealed a mild cardiac dysfunction in ≥4-month-old 5-HTT knockout (-/-) animals. Following induction of chronic cardiac dysfunction (CCD) by MI vs. sham operation 5-HTT-/- mice with infarct sizes >30% experienced 100% mortality, while 50% of 5-HTT+/- and 37% of 5-HTT+/+ animals with large MI survived the 8-week observation period. Surviving (sham and MI < 30%) 5-HTT-/- mutants displayed reduced exploratory activity and increased anxiety-like behavior in different approach-avoidance tasks. However, CCD failed to provoke a depressive-like behavioral response in either 5-Htt genotype. Mechanistic analyses were performed on mice 3 days post-MI. Electrocardiography, histology and FACS of inflammatory cells revealed no abnormalities. However, gene expression of inflammation-related cytokines (TGF-ß, TNF-α, IL-6) and MMP-2, a protein involved in the breakdown of extracellular matrix, was significantly increased in 5-HTT-/- mice after MI. This study shows that 5-HTT deficiency leads to age-dependent cardiac dysfunction and disrupted early healing after MI probably due to alterations of inflammatory processes in mice.

Impaired fear learning and extinction, but not generalization, in anxious and non-anxious depression.

Fear conditioning and generalization are well-known mechanisms in the pathogenesis of anxiety disorders. Extinction of conditioned fear responses is crucial for the psychotherapeutic treatment of these diseases. Anxious depression as a subtype of major depression shares characteristics with anxiety disorders. We therefore aimed to compare fear learning mechanisms in patients with anxious versus non-anxious depression. Fear learning mechanisms in patients with major depression (n = 79; for subgroup analyses n = 41 patients with anxious depression and n = 38 patients with non-anxious depression) were compared to 48 healthy participants. We used a well-established differential fear conditioning paradigm investigating acquisition, generalization, and extinction. Ratings of valence, arousal and probability of expected threat were assessed as well as skin conductance response as an objective psychophysiological measure. Patients with major depression showed impaired acquisition of conditioned fear. In addition, depressed patients showed impaired extinction of conditioned fear responses after successful fear conditioning. Generalization was not affected. However, there was no difference between patients with anxious and non-anxious depression. Results differed between objective and subjective measures. Our findings show altered fear acquisition and extinction in major depression as compared to healthy controls, but they do not favor differential fear learning and extinction mechanisms in the pathogenesis of anxious versus non-anxious depression. The results of impaired extinction warrant future studies addressing extinction learning elements in the treatment of depression.