Peripheral serotonin levels as a predictor of antidepressant treatment response: A systematic review.

There are currently no reliable biomarkers to predict clinical response to pharmacological treatments of depressive disorders. Peripheral blood 5-hydroxytryptamine (5-HT; serotonin) has been suggested as a biomarker of antidepressant treatment response, but there has not been an attempt to systematically summarize and evaluate the scientific evidence of this hypothesis. In this systematic review we searched MEDLINE, Embase, PsycINFO, and the Cochrane Central Register of Controlled Trials. Twenty-six relevant studies investigating peripheral 5-HT as an antidepressant biomarker were identified. In all, we did not find robust support for an association between baseline 5-HT and treatment response. Several larger studies with lower risk of bias, however, showed that higher baseline 5-HT was associated with a greater antidepressant response to SSRIs, prompting future studies to investigate this hypothesis. Our results also confirm previous reports that SSRI treatment is associated with a decrease in peripheral 5-HT levels; however, we were not able to confirm that larger decreases of 5-HT are associated with better treatment outcome as results were inconclusive.

Inflammatory depression is associated with selective glomerular hypofiltration.

BACKGROUND: Systemic low-grade inflammation may be a pathophysiological mechanism in a subtype of depression. In this study we investigate a novel candidate mechanism of inflammatory depression - Selective Glomerular Hypofiltration Syndromes (SGHS) - which are characterized by a reduced estimated glomerular filtration rate (eGFR) based on cystatin C (cysC) relative to eGFR based on creatinine (crea). SGHS have been associated with increased blood levels of pro-inflammatory markers, but have never been investigated in a sample of depressed individuals. METHOD: The prevalence of SGHS was compared between 313 patients with difficult-to-treat depression and 73 controls. Since there is no single established eGFRcysC/eGFRcrea-ratio cut-off to define SGHS, several cut-offs were investigated in relation to a depression diagnosis, inflammation, and symptom severity. Plasma inflammatory markers tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), interleukin (IL)-6, IL-8, and IL-10 were available from 276 depressed patients. We examined mediation effects of IL-6 on the relationship between SGHS and depression. RESULTS: Depressed patients were more likely to have SGHS compared to controls defining SGHS as either eGFRcysC/eGFRcrea-ratio < 0.9 (33.2 % vs 20.5 %, p = 0.035) or < 0.8 (15.7 % vs 5.5 %, p = 0.023). Lower eGFRcysC/eGFRcrea-ratio was associated with higher levels of inflammatory markers in depressed patients. IL-6 partly mediated the relationship between SGHS and depression. CONCLUSION: This is the first study to demonstrate a link between SGHS and inflammatory depression. If replicated in independent and longitudinal cohorts, this may prove to be a relevant pathophysiological mechanism in some cases of depression that could be targeted in future intervention and prevention studies.

CYP2D6 Genotyping and Inhibition as Predictors of Adverse Drug Reactions in Depressive Disorders.

Objective: The primary aim of this study was to examine the association between the different predicted phenotypes of the polymorphic CYP2D6 gene and the prevalence of adverse drug reactions in patients suffering from depressive disorders. The secondary aim was to investigate if comedication with CYP2D6 inhibitors resulted in more adverse drug reactions due to phenoconversion.Methods: Between January 2012 and December 2021, 415 patients with a depressive disorder and insufficient treatment response in secondary psychiatric care were included in the naturalistic observational study Genes, Depression, and Suicidality (GEN-DS). The patients were subjected to a semistructured interview and diagnosed according to DSM-IV. Patients were also required to complete the self-rating version of the UKU Side Effect Rating Scale. All patients were genotyped for CYP2D6 and assigned a corresponding predicted CYP2D6 phenotype.Results: Out of the 415 patients, 147 patients with available genotyping and UKU scale results were also prescribed 1 or more drugs metabolized by CYP2D6. We did not find any evidence of an effect of the predicted CYP2D6 phenotype on the total burden of adverse drug reactions or in any of the specific symptom domains as measured with the UKU scale among these patients. We also investigated if comedication with 1 or more substances that inhibited the effect of the CYP2D6 enzyme resulted in more reported adverse drug reactions due to phenoconversion. Even though the rate of phenotypic PMs increased from 13 to 38 patients, we did not find any support for increased adverse drug reactions in this group.Conclusions: We did not find that CYP2D6 phenotype could predict the occurrence of adverse drug reactions in patients with depressive disorders in this naturalistic setting. However, information about CYP2D6 genotype may still be important in antidepressant treatment for the selection of appropriate drugs, for dosing recommendations of certain medications, or when the patient is suffering from severe adverse reactions.

Add-on pramipexole for anhedonic depression: study protocol for a randomised controlled trial and open-label follow-up in Lund, Sweden.

INTRODUCTION: Many depressed patients do not achieve remission with available treatments. Anhedonia is a common residual symptom associated with treatment resistance as well as low function and quality of life. There are currently no specific and effective treatments for anhedonia. Some trials have shown that dopamine agonist pramipexole is efficacious for treating depression, but more data is needed before it could become ready for clinical prime time. Given its mechanism of action, pramipexole might be a useful treatment for a depression subtype characterised by significant anhedonia and lack of motivation-symptoms associated with dopaminergic hypofunction. We recently showed, in an open-label pilot study, that add-on pramipexole is a feasible treatment for depression with significant anhedonia, and that pramipexole increases reward-related activity in the ventral striatum. We will now confirm or refute these preliminary results in a randomised controlled trial (RCT) and an open-label follow-up study. METHODS AND ANALYSIS: Eighty patients with major depression (bipolar or unipolar) or dysthymia and significant anhedonia according to the Snaith Hamilton Pleasure Scale (SHAPS) are randomised to either add-on pramipexole or placebo for 9 weeks. Change in anhedonia symptoms per the SHAPS is the primary outcome, and secondary outcomes include change in core depressive symptoms, apathy, sleep problems, life quality, anxiety and side effects. Accelerometers are used to assess treatment-associated changes in physical activity and sleep patterns. Blood and brain biomarkers are investigated as treatment predictors and to establish target engagement. After the RCT phase, patients continue with open-label treatment in a 6-month follow-up study aiming to assess long-term efficacy and tolerability of pramipexole. ETHICS AND DISSEMINATION: The study has been approved by the Swedish Ethical Review Authority and the Swedish Medical Products Agency. The study is externally monitored according to Good Clinical Practice guidelines. Results will be disseminated via conference presentations and peer-reviewed publications. TRIAL REGISTRATION NUMBER: NCT05355337 and NCT05825235.

An inflamed subtype of difficult-to-treat depression.

BACKGROUND: Chronic low-grade inflammation may play a role in the pathophysiology of depression, at least in a subset of patients. High-sensitivity C-reactive protein (hs-CRP) has been used to define an inflamed subgroup of depression with specific clinical characteristics and symptoms. In this study we investigated biochemical and clinical characteristics in patients with difficult-to-treat depression with and without chronic low-grade inflammation. METHOD: We assayed plasma levels of interferon-gamma, tumor necrosis factor-alpha, Interleukin (IL)-10, IL-6, IL-8, and vitamin D in a clinically well-characterized sample of patients with difficult-to-treat depression (n = 263) and healthy controls (n = 46). Serum hs-CRP levels were available in the patient group and were used to define "inflamed depression" (hs-CRP > 3 mg/L). Based on previous studies correlating specific depressive symptoms to inflammatory markers, we calculated a composite score of inflammatory depressive symptoms (Infl-Dep score). A principal component analysis (PCA) was performed to identify patterns of variance in cytokines and vitamin D among patients. RESULTS: Mean levels of IL-6 and IL-8 were significantly higher in depressed patients compared to controls, also after adjusting for sex, smoking, BMI, and age. None of the other inflammatory markers differed significantly between depressed patients and controls. Two components were extracted using PCA; one showed general cytokine elevations and one represented a pattern where IL-6 and IL-8 were inversely related to vitamin D (IL6-IL8-VitD component). The inflamed subgroup (hs-CRP > 3, n = 51) exhibited significantly higher BMI, higher Infl-Dep scores and higher IL6-IL8-VitD component scores than uninflamed patients (hs-CRP ≤ 3, n = 212). There were no significant differences in overall depression severity or suicidality between the inflamed and uninflamed groups. CONCLUSION: Our results support the hypothesis of an inflamed subgroup of depression as a meaningful construct. This subgroup may have certain biological and clinical characteristics and more studies are needed to determine potential clinical implications.

Plasma circulating cell-free mitochondrial DNA in depressive disorders.

BACKGROUND: Plasma circulating cell-free mitochondrial DNA (ccf-mtDNA) is an immunogenic molecule and a novel biomarker of psychiatric disorders. Some previous studies reported increased levels of ccf-mtDNA in unmedicated depression and recent suicide attempters, while other studies found unchanged or decreased ccf-mtDNA levels in depression. Inconsistent findings across studies may be explained by small sample sizes and between-study variations in somatic and psychiatric co-morbidity or medication status. METHODS: We measured plasma ccf-mtDNA in a cohort of 281 patients with depressive disorders and 49 healthy controls. Ninety-three percent of all patients were treated with one or several psychotropic medications. Thirty-six percent had a personality disorder, 13% bipolar disorder. All analyses involving ccf-mtDNA were a priori adjusted for age and sex. RESULTS: Mean levels in ccf-mtDNA were significantly different between patients with a current depressive episode (n = 236), remitted depressive episode (n = 45) and healthy controls (n = 49) (f = 8.3, p<0.001). Post-hoc tests revealed that both patients with current (p<0.001) and remitted (p = 0.002) depression had lower ccf-mtDNA compared to controls. Within the depressed group there was a positive correlation between ccf-mtDNA and "inflammatory depression symptoms" (r = 0.15, p = 0.02). We also found that treatment with mood stabilizers lamotrigine, valproic acid or lithium was associated with lower ccf-mtDNA (f = 8.1, p = 0.005). DISCUSSION: Decreased plasma ccf-mtDNA in difficult-to-treat depression may be partly explained by concurrent psychotropic medications and co-morbidity. Our findings suggest that ccf-mtDNA may be differentially regulated in different subtypes of depression, and this hypothesis should be pursued in future studies.

Differences in antipsychotic treatment between depressive patients with and without a suicide attempt.

BACKGROUND: Depressed suicide attempters are, according to some earlier studies, treated more often with antipsychotics than depressive non-suicide attempters. Cluster B personality disorders, especially borderline personality disorder, are associated with a high suicide risk, and antipsychotics are commonly used for the reduction of symptoms. However, no previous study has taken comorbid personality disorders into account when assessing the use of antipsychotics in patients with unipolar depression. Therefore, the aim of this study was to investigate the clinical selection of pharmacotherapy in unipolar depression with and without a previous suicide attempt, taking into account potential confounders such as cluster B personality disorders. METHODS: The study sample consisted of 247 patients with unipolar depression. The study was approved by the Regional Ethical Review Board in Lund, Sweden. Study participants were recruited from 4 different secondary psychiatric care clinics in Sweden and were diagnosed according to the DSM-IV-TR with the MINI and SCID II. Previous and ongoing psychiatric treatments were investigated in detail and medical records were assessed. RESULTS: Thirty percent of the patients had made previous suicide attempts. Depressed suicide attempters underwent both lifetime treatment with antipsychotics and an ongoing antipsychotic treatment significantly more often than non-attempters. Significances remained after a regression analysis, adjusting for cluster B personality disorders, symptom severity, age at the onset of depression, and lifetime psychotic symptoms. CONCLUSIONS: This is the first study to consider the effect of comorbidity with cluster B personality disorders when comparing treatment of depressive suicide and non-suicide attempters. Our findings suggest that suicide attempters are more frequently treated with antipsychotics compared to non-suicide attempters, regardless of cluster B personality disorder comorbidity. These findings are important for clinicians to consider and would also be relevant to future studies evaluating reduction of suicide risk with antipsychotics in patients with psychiatric comorbidity and a history of attempted suicide.

Recognition of personality disorder and anxiety disorder comorbidity in patients treated for depression in secondary psychiatric care.

OBJECTIVES: Depression is a common illness with substantial economic consequences for society and a great burden for affected individuals. About 30% of patients with depression do not respond to repeated treatments. Psychiatric comorbidity is known to affect duration, recurrence and treatment outcome of depression. However, there is a lack of knowledge on the extent to which psychiatric comorbidity is identified in the clinical setting for depressed patients in secondary psychiatric care. Therefore, the aim of this study was to compare the agreement between traditional diagnostic assessment (TDA) and a structured and comprehensive diagnostic procedure (SCDP) for identification of personality and anxiety disorder comorbidity in depressed patients in secondary psychiatric care. METHODS: 274 patients aged 18-77 were referred from four secondary psychiatric care clinics in Sweden during 2012-2017. ICD-10 diagnoses according to TDA (mostly unstructured by psychiatric specialist and residents in psychiatry), were retrieved from medical records and compared to diagnoses resulting from the SCDP in the study. This included the Mini International Neuropsychiatric Interview, the Structured Interview for DSM Axis II Personality Disorders and semi-structured questions on psychosocial circumstances, life-events, psychiatric symptoms, psychiatric treatments, substance use, and suicidal and self-harm behaviour. The assessment was carried out by psychiatric specialists or by residents in psychiatry with at least three years of psychiatric training. RESULTS: SCDP identified personality disorder comorbidity in 43% of the patients compared to 11% in TDA (p<0,0001). Anxiety disorder comorbidity was identified in 58% with SCDP compared to 12% with TDA (p<0,0001). CONCLUSIONS: Important psychiatric comorbidity seems to be unrecognized in depressive patients when using TDA, which is routine in secondary psychiatric care. Comorbidities are better identified using the proposed model involving structured and semi-structured interviews together with clinical evaluations by clinical experts.

Coping and suicide risk in high risk psychiatric patients.

Background: A dysfunctional use of coping strategies has repeatedly been linked to suicidal behaviour in non-psychiatric populations. However, data regarding association between coping strategies and suicidal behaviour in psychiatric populations are limited.Aims: The aim of the study was to investigate the possible relationship between self-reported suicide risk, suicidal ideation and coping strategies in three psychiatric cohorts.Method: Three cohorts of psychiatric patients were involved in the study; recent suicide attempters (n = 55), suicide attempters at follow-up 12 years after a suicide attempt (n = 38) and patients with ongoing depression without attempted suicide (n = 72). Patients filled in the self-rating version of The Suicide Assessment Scale (SUAS-S) from which items no. 17-20 addressing current suicidal ideation were extracted. To investigate coping strategies, the Coping Orientation of Problem Experience Inventory (COPE) was used.Results: In all cohorts, regression analyses showed that only avoidant coping was significantly correlated with the scores of SUAS-S adjusted for covariates. The items no. 17-20 correlated significantly to avoidant coping but not with other coping strategies in all cohorts.Conclusion: The results of this study indicate that among coping strategies only avoidant coping may be associated with suicide risk in psychiatric patients independently of history of attempted suicide.

Low total cholesterol and low-density lipoprotein associated with aggression and hostility in recent suicide attempters.

Low cholesterol levels have been correlated with both suicidal and aggressive behavior in psychiatric patients. Few studies have investigated associations between serum lipid profiles and both aggressive state and trait. Fifty-two psychiatric medication-free inpatients were included in this study after a suicide attempt. Composite scores of "State Aggression" and "Trait Aggression" were calculated using relevant items from the Comprehensive Psychopathological Rating Scale and the Karolinska Scales of Personality. State Aggression was significantly and negatively correlated with total cholesterol (TC) and low-density lipoprotein (LDL). Trait Aggression was also significantly and negatively correlated with LDL, but not TC. There were small but significant mediation effects of severity of anxiety symptoms on the relationship between State Aggression and TC as well as LDL. In exploratory analyses we found that low cholesterol was also associated with personality traits of hostility. Moreover, low cholesterol was more robustly associated with personality trait items related to interpersonal aggression, as opposed to items related to irritability or more indirect, non-overt aggression. Our findings suggest that low cholesterol is associated with both state and trait aggression in suicide attempters. Future mechanistic studies are warranted to better understand the relationship between low cholesterol and high aggression in suicide attempters.