Higher serotonin transporter availability in early-onset obsessive-compulsive disorder patients undergoing escitalopram treatment: A [11 C]DASB PET study

Early-onset obsessive-compulsive disorder: Sociodemographic and clinical characterization of a large outpatient cohort

INTRODUCTION

Obsessive-compulsive disorder (OCD) is a prevalent and disabling condition characterized by a wide variety of phenotypic expressions. Several studies have reinforced the hypothesis of OCD heterogeneity by proposing subtypes based on predominant symptomatology, course, and comorbidities. Early-onset OCD (EO) could be considered a neurodevelopmental subtype of OCD, with evidence of distinct neurocircuits supporting disease progression. To deepen the heterogeneous nature of the disorder, we analyzed sociodemographic and clinical differences between the EO and late-onset (LO) subtypes in a large outpatient cohort.

METHODS

Two hundred and eighty-four patients diagnosed with OCD were consecutively recruited from the OCD Tertiary Clinic at Luigi Sacco University Hospital in Milan. Sociodemographic and clinical variables were analyzed for the entire sample and compared between the two subgroups (EO, age <18 years [n = 117,41.2 %]; LO: late-onset, age ≥18 years [n = 167, 58.8 %]).

RESULTS

The EO group showed a higher frequency of male gender (65 % vs 42.5 %, p < .001), and a higher prevalence of Tic and Tourette disorders (9.4 % vs 0 %, p < .001) compared to the LO group. Additionally, in the EO subgroup, a longer duration of untreated illness was observed (9.01 ± 9.88 vs 4.81 ± 7.12; p < .001), along with a lower presence of insight (13.8 % vs. 7.5 %, p < .05).

CONCLUSIONS

The early-onset OCD subtype highlights a more severe clinical profile compared to the LO group. Exploring distinct manifestations and developmental trajectories of OCD can contribute to a better definition of homogeneous subtypes, useful for defining targeted therapeutic strategies for treatment.

Progress in the application of molecular imaging in psychiatric disorders

Psychiatric disorders have always attracted a lot of attention from researchers due to the difficulties in their diagnoses and treatments. Molecular imaging, as an emerging technology, has played an important role in the researchers of various diseases. In recent years, molecular imaging techniques including magnetic resonance spectroscopy, nuclear medicine imaging, and fluorescence imaging have been widely used in the study of psychiatric disorders. This review will briefly summarize the progression of molecular imaging in psychiatric disorders.

Radiotracers for the Central Serotoninergic System

This review lists the most important radiotracers described so far for imaging the central serotoninergic system. Single-photon emission computed tomography and positron emission tomography radiotracers are reviewed and critically discussed for each receptor.

Exploring Association Between Serotonin and Neurogenesis Related Genes in Obsessive-Compulsive Disorder in Chinese Han People: Promising Association Between DMRT2, miR-30a-5p, and Early-Onset Patients

Obsessive-compulsive disorder (OCD) is a deliberating disorder with complex genetic and environmental etiologies. Hypotheses about OCD mainly include dysregulated neurotransmitters, especially serotonin, and disturbed neurodevelopment. Single nucleotide polymorphism (SNP) association studies regarding OCD are often met with inconsistent results. However, stratification by age of onset may sometimes help to limit the heterogenicity of OCD patients. Therefore, we conducted a stratified SNP association study enrolling 636 patients and 612 healthy controls. Patients were stratified by age of onset as early-onset (EO-OCD) and late-onset (LO-OCD). Blood extracted from the patients was used to genotype 18 loci, including serotonin system genes, Slitrk1, Slitrk5, and DMRT2 and related miRNA genes. Logistic regression was used to compare allele and genotype frequencies of variants. A general linear model was used to evaluate the association between variants and trait anxiety. In our study, rs3824419 in DMRT2 was associated with EO-OCD, G allele was the risk allele. Rs2222722 in miR-30a-5p was associated with EO-OCD, with the C allele being the risk allele. Rs1000952 in HTR3D was found associated with trait anxiety in OCD patients. The significance disappeared after FDR correction. Our results supported neurodevelopment-related genes, DMRT2 and miR-30a-5p, to be related to EO-OCD. However, we cannot prove serotonin genes to be directly associated with EO-OCD. While an association between HTR3D and trait anxiety was discovered, comparisons based on biological or clinical traits may be helpful in future studies. As our detective powers were limited, more large-scale studies will be needed to confirm our conclusion.

Update on PET imaging biomarkers in the diagnosis of neuropsychiatric disorders

PURPOSE OF REVIEW

To give an update on recent imaging studies probing positron emission tomography (PET) as a tool for improving biomarker-guided diagnosis of neuropsychiatric disorders.

RECENT FINDINGS

Several studies confirmed the value of imaging of regional neuronal activity and imaging of dopaminergic, serotonergic, and other neuroreceptor function in the diagnostic process of neuropsychiatric disorders, particularly schizophrenia, depression/bipolar disorder, substance use disorders, obsessive compulsive disorders (OCD), and attention-deficit/hyperactivity disorder. Additionally, imaging brain microglial activation using translocator protein 18 kDa (TSPO) radiotracer allows for unique in-vivo insights into pathophysiological neuroinflammatory changes underlying schizophrenia, affective disorders, and OCD.

SUMMARY

The role of PET imaging in the biomarker-guided diagnostic process of neuropsychiatric disorders has been increasingly acknowledged in recent years. Future prospective studies are needed to define the value of PET imaging for diagnosis, treatment decisions, and prognosis in neuropsychiatric disorders.

Effect of Escitalopram on Serum GDNF and BDNF Levels and 5-HT Level of Brain Tissue of Obsessive-Compulsive Disorder Rats

The present study aims to discuss the effect of escitalopram in glial cell line-derived neurotrophic factor (GDNF), brain-derived neurotrophic factor (BDNF) levels, and 5-Hydroxytryptamine (5-HT) in obsessive-compulsive disorder rats. A total of 42 rats were divided into three groups randomly: control group (n = 14), model group (n = 14) (obsessive-compulsive disorder group), and escitalopram group (n = 14) (model + obsessive-compulsive disorder group + escitalopram treatment). The open-field method was used to test the rat behavior, enzyme-linked immunosorbent assay (ELISA) was used to determine the serum GDNF and BDNF levels. In addition, Western blot was used to determine the brain tissue protein levels of GDNF and BDNF and high-performance liquid chromatography + electrochemistry method to determine the 5-HT level of brain tissue. Visiting place was changed, rotational frequency and fixed duration enhanced in escitalopram group compared to model group (P < 0.05). Besides, GDNF and BDNF levels of serum and brain tissue were decreased in model group and escitalopram group compared to control group (P < 0.05), while GDNF and BDNF levels of serum and brain tissue were increased in escitalopram group compared to model group (P < 0.05). Moreover, the 5-HT level of brain tissue in escitalopram group was higher than that in model group (P < 0.05). Escitalopram could increase GDNF and BDNF levels and 5-HT content in serum and brain tissue in obsessive-compulsive disorder rats, which contributes to a function on the treatment of obsessive-compulsive disorder.

Functional connectivity of the raphe nucleus as a predictor of the response to selective serotonin reuptake inhibitors in obsessive-compulsive disorder

Selective serotonin reuptake inhibitors (SSRIs) are first-line pharmacological agents for treating obsessive-compulsive disorder (OCD). However, because nearly half of patients show insufficient SSRI responses, serotonergic dysfunction in heterogeneous OCD patients should be investigated for precision medicine. We aimed to determine whether functional connectivity (FC) of the raphe nucleus (RN), the major source of most serotonergic neurons, was altered in OCD patients and could predict the SSRI response. A total of 102 medication-free OCD patients and 101 matched healthy control (HC) subjects participated in resting-state functional magnetic resonance imaging. Among them, 54 OCD patients were treated with SSRIs for 16 weeks, resulting in 26 responders and 28 nonresponders. Seed-based whole brain FC with the RN as a seed region was compared between the OCD and HC groups, as well as between SSRI responders and nonresponders. FC cluster values showing significant group differences were used to investigate factors correlated with symptomatic severity before treatment and predictive of SSRI response. Compared to HCs, OCD patients exhibited significantly larger FC between the RN and temporal cortices including the middle temporal gyrus (MTG), paracingulate gyrus, amygdala, hippocampus, putamen, thalamus, and brain stem. Greater RN-left MTG FC was positively correlated with OC symptom severity at baseline. In addition, larger FC of the RN-left MTG was also found in SSRI nonresponders compared to responders, which was a significant predictor of SSRI response after 16 weeks. The FC of RN may reflect the neurobiological underpinning of OCD and could aid future precision medicine as a differential brain-based biomarker.

Current Enlightenment About Etiology and Pharmacological Treatment of Autism Spectrum Disorder

Autistic Spectrum Disorder (ASD) is a complex neurodevelopmental brain disorder characterized by two core behavioral symptoms, namely impairments in social communication and restricted/repetitive behavior. The molecular mechanisms underlying ASD are not well understood. Recent genetic as well as non-genetic animal models contributed significantly in understanding the pathophysiology of ASD, as they establish autism-like behavior in mice and rats. Among the genetic causes, several chromosomal mutations including duplications or deletions could be possible causative factors of ASD. In addition, the biochemical basis suggests that several brain neurotransmitters, e.g., dopamine (DA), serotonin (5-HT), gamma-amino butyric acid (GABA), acetylcholine (ACh), glutamate (Glu) and histamine (HA) participate in the onset and progression of ASD. Despite of convincible understanding, risperidone and aripiprazole are the only two drugs available clinically for improving behavioral symptoms of ASD following approval by Food and Drug Administration (FDA). Till date, up to our knowledge there is no other drug approved for clinical usage specifically for ASD symptoms. However, many novel drug candidates and classes of compounds are underway for ASD at different phases of preclinical and clinical drug development. In this review, the diversity of numerous aetiological factors and the alterations in variety of neurotransmitter generation, release and function linked to ASD are discussed with focus on drugs currently used to manage neuropsychiatric symptoms related to ASD. The review also highlights the clinical development of drugs with emphasis on their pharmacological targets aiming at improving core symptoms in ASD.