A walk on the dark side: TMS over the right inferior frontal gyrus (rIFG) disrupts behavioral responses to infant stimuli

Improving social cognition following theta burst stimulation over the right inferior frontal gyrus in autism spectrum: an 8-week double-blind sham-controlled trial

BACKGROUND

The right inferior frontal gyrus (RIFG) is a potential beneficial brain stimulation target for autism. This randomized, double-blind, two-arm, parallel-group, sham-controlled clinical trial assessed the efficacy of intermittent theta burst stimulation (iTBS) over the RIFG in reducing autistic symptoms (NCT04987749).

METHODS

Conducted at a single medical center, the trial enrolled 60 intellectually able autistic individuals (aged 8-30 years; 30 active iTBS). The intervention comprised 16 sessions (two stimulations per week for eight weeks) of neuro-navigated iTBS or sham over the RIFG. Fifty-seven participants (28 active) completed the intervention and assessments at Week 8 (the primary endpoint) and follow-up at Week 12.

RESULTS

Autistic symptoms (primary outcome) based on the Social Responsiveness Scale decreased in both groups (significant time effect), but there was no significant difference between groups (null time-by-treatment interaction). Likewise, there was no significant between-group difference in changes in repetitive behaviors and exploratory outcomes of adaptive function and emotion dysregulation. Changes in social cognition (secondary outcome) differed between groups in feeling scores on the Frith-Happe Animations (Week 8, p = 0.026; Week 12, p = 0.025). Post-hoc analysis showed that the active group improved better on this social cognition than the sham group. Dropout rates did not vary between groups; the most common adverse event in both groups was local pain. Notably, our findings would not survive stringent multiple comparison corrections.

CONCLUSIONS

Our findings suggest that iTBS over the RIFG is not different from sham in reducing autistic symptoms and emotion dysregulation. Nonetheless, RIFG iTBS may improve social cognition of mentalizing others' feelings in autistic individuals.

Oxytocin-Receptor Gene Modulates Reward-Network Connection and Relationship with Empathy Performance

Introduction

Empathy traits are highly heritable and linked with reward processing. It is implicated that common variations of the oxytocin-receptor gene (OXTR) play a modulatory effect on empathic performance. However, it is unclear about the neural substrates underlying the modulatory effect of the OXTR genotype on empathic performance. This study aimed to characterize the modulatory effect of common OXTR variations on reward-circuitry function and its relationship with empathy.

Methods

Based on the seed of the nucleus accumbens (NAcc; a key hub of reward circuitry), we examined differences in spontaneous local activity and functional connectivity between OXTR rs2268493 genotype groups and their relationship with empathic performance among 402 high-homogeneity participants.

Results

Comparing with C carriers (CC/CT) group, the individuals with the rs2268493 TT genotype exhibited lower functional connectivity of the right NAcc with the medial prefrontal cortex (mPFC) and inferior frontal gyrus. Similarly lower functional connectivity was found between the left NAcc and mPFC. Consequently, no significant difference was found in the spontaneous local activity of NAcc.

Discussion

Our findings suggested that common OXTR variations have a modulatory effect on the connection of the NAcc with the hub of empathic networks (mPFC and IFG), which may provide insight on the neural substrate underlying the modulatory effect of OXTR on empathic behavior.

A randomized wait-list controlled trial to investigate the role of cognitive mechanisms in parenting interventions on mothers with substance use disorder

Background

Maternal substance use disorder (SUD) represents a risk condition for quality of parenting and child development. The current literature highlights the need to identify interventions that effectively enhance the quality of parenting and to better understand which mechanisms are involved in the process of change. The present study protocol describes a randomized wait-list controlled trial that aims to examine (1) the efficacy of the Video-feedback Intervention to promote Positive Parenting and Sensitive Discipline (VIPP-SD) in improving the quality of parenting (i.e., sensitive parenting and sensitive discipline) in mothers with SUD, (2) whether the intervention affects parental cognitive mechanisms (i.e., attentional disengagement to infant negative emotions, inhibitory control confronted with children’s affective expression, and parental reflective functioning), and (3) whether changes in these processes act as mechanisms of change, mediating the effect of the VIPP-SD program on quality of parenting. Moreover, the study aims (4) to explore whether the VIPP-SD has an effect on parenting stress and (5) to compare mothers with SUD to low-risk mothers on the outcome measures.

Methods

The study will involve 40 mothers with SUD and 20 low-risk mothers of children aged between 14 months and 6 years old. Mothers in the SUD group will be randomly divided into two groups, one receiving the intervention (SUD experimental group) and one undergoing treatment as usual (SUD control group). All the mothers will be assessed pre-test and post-test. Quality of parenting will be assessed through observed parenting behaviors, whereas parental cognitive mechanisms will be assessed through neuropsychological tasks and self-report measures.

Discussion

The results of the study will reveal whether an intervention that has been proven effective in other at-risk samples is also effective in improving parenting behaviors in the context of SUD. The results will also provide insight into potential cognitive mechanisms involved in the process of change.

Trial registration

ISRCTN registry ISRCTN63070968. Registered on 25 June 2021. Retrospectively registered

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06420-8.

High-definition transcranial direct current stimulation modulates eye gaze on emotional faces in college students with alexithymia: An eye-tracking study

BACKGROUND

Atypical eye gaze on emotional faces is a core feature of alexithymia. The inferior frontal gyrus (IFG) is considered to be the neurophysiological basis of alexithymia-related emotional face fixation. Our aim was to examine whether anodal high-definition transcranial direct current stimulation (HD-tDCS) administered to the right (r)IFG would facilitate eye gaze of emotional faces in alexithymia individuals.

METHOD

Forty individuals with alexithymia were equally assigned to anodal or sham HD-tDCS of the rIFG according to the principle of randomization. The individuals then completed a free-viewing eye tracking task (including happy, sad, and neutral faces) before and after 5 consecutive days of stimulation (twice a day).

RESULTS

The results showed that twice a day anodal HD-tDCS of the rIFG significantly increased the fixation time and fixation count of the eye area on happy and neutral faces, but there was no significant effect on sad faces. According to the temporal-course analysis, after the intervention, the fixation time on neutral faces increased significantly at almost all time points of the eye tracking task. For happy faces, the improvement was demonstrated between 500 and 1000 ms and between 2500 and 3500 ms. For sad faces, the fixation time improved but not significantly.

CONCLUSIONS

Applying high-dose anodal HD-tDCS to the rIFG selectively facilitated eye gaze in the eye area of neutral and happy faces in individuals with alexithymia, which may improve their face processing patterns.

DNA Methylation and Allelic Polymorphism at the Dopamine Transporter Promoter Affect Internalizing and Externalizing Symptoms in Preschoolers

The role of the dopamine transporter (DAT) in the onset and maintenance of emotional-behavioral difficulties is recognized in adults, adolescents and school-age children, whereas few studies in this field have focused on preschoolers. The study recruited 2-year old children (N = 152) in the general population assessing the possible effect of DAT methylation and allelic polymorphism on internalizing and externalizing symptoms, also exploring whether epigenetic and genetic variability interact. Our results showed that DAT methylation is significantly associated with all the dimensions of children's emotional/behavioral functioning in children carrying 10/10-3/3-8/10 polymorphisms but not in children carrying 9/10-9/9 allele repeats. Understanding the influence of genetic/epigenetic factors on maladaptive emotional/behavioral outcomes in young children, can be of great help in programming effective prevention and intervention plans and can be a valid aid to alleviate psychopathological symptoms before they crystalize into more severe clinical conditions in later life.

Mothers' alexithymia in the context of parental Substance Use Disorder: Which implications for parenting behaviors?

BACKGROUND

Maternal substance use disorder (SUD) represents a severe risk for caregiving, affecting diverse domains of parenting behaviors, such as sensitivity, structuring, intrusiveness, and hostility. Various studies highlighted that difficulties in parenting behaviors in the context of SUD are exacerbated by the co-occurrence of psychopathological symptoms. A large body of research points out the presence of high rates of alexithymia in individuals with SUD, and some studies provide evidence of an association between this psychopathological aspect and parenting. Nevertheless, no prior research has explored how alexithymic traits could affect quality of parenting behaviors in mothers with SUD.

OBJECTIVE

To investigate the impact of maternal alexithymia on parenting behaviors in mothers with SUD.

METHODS

Sixty women in residential treatment for SUD and their children participated in the study. The participants were assessed with respect to alexithymia, quality of parenting behaviors, and depressive symptoms.

RESULTS

Forty-three percent of the mothers reported the presence of alexithymia. These mothers presented with significantly low scores on sensitivity (β = -.25, p < .05) and structuring (β = -.32, p < .05). After controlling for depressive symptomatology, the effect of alexithymia on parenting behaviors remained only for structuring (β=.35, p < .05).

CONCLUSIONS

In the context of SUD, maternal alexithymia significantly impacts the quality of parenting behaviors, specifically structuring, indicating that difficulties in becoming aware of one's own feelings jeopardize the ability to scaffold interactions and set age-appropriate limits in an emotionally attuned way. Clinical implications of the findings are discussed.