The serotonin transporter gene polymorphism (SLC6A4) and risk for psychiatric morbidity and comorbidity in the Baltimore ECA follow-up study

Pharmacogenetics of selective serotonin reuptake inhibitors (SSRI): A serotonin reuptake transporter (SERT)-based approach

Neuropsychiatric disorders are considered to be the most common cause of disability worldwide. Serotonin and its transporter is a prominent paradigm in mood disorders. Response to selective serotonin reuptake inhibitors (SSRI) is altered due to heterogeneity in the serotonin transporter gene, SLC6A4 (solute carrier family 6 member 4). The reported polymorphisms are found to be in different regions of the transporter gene: promoter region (5-HTTLPR and various single nucleotide polymorphisms within it), intron (STin2), and exon 9 (I425V). The long and short alleles of the 5-HTTLPR gene, which are prevalent among variations, may mediate differential effects. In long allelic variant carriers, an increased response to SSRI and timely recovery is due to increased availability of SERT. Whereas, SERT availability is significantly decreased in short allelic carriers, necessitating a reduction in SSRI dosage due to the increased risk of adverse drug reactions. Thus, pharmacogenetic investigations are required to understand the impact of functional variations on the efficacy and tolerability of SSRI. Identifying the carrier variants may aid in clear-decision making of the treatment regimen, aiding the approach of personalized medication.

Regional homogeneity in patients with obsessive-compulsive disorder and depression: A resting state functional magnetic resonance imaging study

OBJECTIVE

To explore the brain functional impairment of patients with obsessive-compulsive disorder (OCD) with and without depressive symptoms and analyze the correlation between the degree of impairment and the severity of symptoms.

METHOD

Fourteen patients with OCD who met the ICD-10 diagnostic criteria for OCD were included. The group having OCD with depression (OCDd) consisted of 15 patients, and 17 healthy controls (HC) matched for age and education were also included. The Yale-Brown OCD Scale (Y-BOCS) and the 24-item Hamilton Assessment of Depression Scale (HAMD) were administered to the OCD and OCDd groups. Resting-state functional brain magnetic resonance imaging was performed in the three groups of participants.

RESULT

The OCDd group had lower scores on the HAMD, Y-BOCS, and obsessive-compulsive thinking subscales compared with the OCD group (P < 0.05). The scores on the OCDd subscale were negatively correlated with the HAMD scores (R =  - 0.568, P = 0.027). The OCDd group had higher regional homogeneity (ReHo) values in the lingual gyrus than the OCD group. The OCDd group had higher ReHo values in the lingual gyrus than the HC group, and the OCDd group had higher ReHo values than the HC group. These differences were statistically significant (P < 0.05). After correction for multiple comparisons, significant difference was observed between the OCDd and HC groups (P＜0.05). In the OCD group, the ReHo value of the lingual gyrus was negatively correlated with the Y-BOCS total score and the compulsive behavior subscale score (R =  - 0.609, -0.552; P = 0.016, 0.033).

CONCLUSION

Abnormal ReHo values in the lingual gyrus and right medial superior frontal gyrus were found in the patients with OCDd. In the OCDd group, the ReHo values of the lingual gyrus were negatively correlated with the scores on the Y-BOCS total and obsessive-compulsive subscales, suggesting that abnormal local coherence of the lingual gyrus may be related to the severity of OCD.

The Relationship between Maternal Antibodies to Fetal Brain and Prenatal Stress Exposure in Autism Spectrum Disorder

Environmental and genetic factors contribute to the etiology of autism spectrum disorder (ASD), but their interaction is less well understood. Mothers that are genetically more stress-susceptible have been found to be at increased risk of having a child with ASD after exposure to stress during pregnancy. Additionally, the presence of maternal antibodies for the fetal brain is associated with a diagnosis of ASD in children. However, the relationship between prenatal stress exposure and maternal antibodies in the mothers of children diagnosed with ASD has not yet been addressed. This exploratory study examined the association of maternal antibody response with prenatal stress and a diagnosis of ASD in children. Blood samples from 53 mothers with at least one child diagnosed with ASD were examined by ELISA. Maternal antibody presence, perceived stress levels during pregnancy (high or low), and maternal 5-HTTLPR polymorphisms were examined for their interrelationship in ASD. While high incidences of prenatal stress and maternal antibodies were found in the sample, they were not associated with each other (p = 0.709, Cramér's V = 0.051). Furthermore, the results revealed no significant association between maternal antibody presence and the interaction between 5-HTTLPR genotype and stress (p = 0.729, Cramér's V = 0.157). Prenatal stress was not found to be associated with the presence of maternal antibodies in the context of ASD, at least in this initial exploratory sample. Despite the known relationship between stress and changes in immune function, these results suggest that prenatal stress and immune dysregulation are independently associated with a diagnosis of ASD in this study population, rather than acting through a convergent mechanism. However, this would need to be confirmed in a larger sample.

Relationships between fear of flying, loudness dependence of auditory evoked potentials and frontal alpha asymmetry

Previous research has suggested that fear of flying, which is defined as a situational, specific phobia, could overlap with depressive and anxiety disorders. Whether the neuronal dysfunctions including altered serotonergic activity in the brain and altered neural oscillations observed for depressive and anxiety disorders also overlap with alterations in fear of flying is unclear. Here, thirty-six participants with self-reported fear of flying (FF) and forty-one unaffected participants (NFF) were recruited. The participants completed the Beck Depression Inventory (BDI-II), the State-trait Anxiety Inventory (STAI) and the Fear of Flying Scale (FFS). EEG-recording was conducted during resting-state and during presentation of auditory stimuli with varying loudness levels for analysis of the Loudness Dependence of Auditory Evoked Potentials (LDAEP), which is suggested to be inversely related to central serotonergic activity. Participants with fear of flying did not differ from the control group with regard to BDI-II and STAI data. The LDAEP was higher over F4 electrode in the FF group compared to controls, whereas exploratory analysis suggest that differences between groups were conveyed by female participants. Moreover, the FF group showed relatively higher right frontal alpha activity compared to the control group, whereas no difference in frequency power (alpha, beta and theta) was observed. Thus, this study brought the first hint for reduced serotonergic activity in individuals with fear of flying and relatively higher right frontal activity. Thus, based on the preliminary findings, future research should aim to examine the boundaries with anxiety and depressive disorders and to clarify the distinct neural mechanisms.