The right hemisphere and psychopathology

Low-intensity transcranial ultrasound stimulation improves memory behavior in an ADHD rat model by modulating cortical functional network connectivity

Working memory in attention deficit hyperactivity disorder (ADHD) is closely related to cortical functional network connectivity (CFNC), such as abnormal connections between the frontal, temporal, occipital cortices and with other brain regions. Low-intensity transcranial ultrasound stimulation (TUS) has the advantages of non-invasiveness, high spatial resolution, and high penetration depth and can improve ADHD memory behavior. However, how it modulates CFNC in ADHD and the CFNC mechanism that improves working memory behavior in ADHD remain unclear. In this study, we observed working memory impairment in ADHD rats, establishing a corresponding relationship between changes in CFNCs and the behavioral state during the working memory task. Specifically, we noted abnormalities in the information transmission and processing capabilities of CFNC in ADHD rats while performing working memory tasks. These abnormalities manifested in the network integration ability of specific areas, as well as the information flow and functional differentiation of CFNC. Furthermore, our findings indicate that TUS effectively enhances the working memory ability of ADHD rats by modulating information transmission, processing, and integration capabilities, along with adjusting the information flow and functional differentiation of CFNC. Additionally, we explain the CFNC mechanism through which TUS improves working memory in ADHD. In summary, these findings suggest that CFNCs are important in working memory behaviors in ADHD.

A meta-analysis on the therapeutic efficacy of repetitive transcranial magnetic stimulation for cognitive functions in attention-deficit/hyperactivity disorders

BACKGROUND

Therapeutic efficacies of repetitive transcranial magnetic stimulation (rTMS) for improving cognitive functions in patients with deficit/hyperactivity disorder (ADHD) remained unclear. The aim of this meta-analysis was to investigate the therapeutic efficacy of rTMS focusing on different cognitive performances.

METHODS

Major databases were searched electronically from inception to February 2023 by using keywords mainly "rTMS" and "ADHD" to identify randomized controlled trials (RCTs) that investigated the therapeutic efficacy of rTMS for improving cognitive functions assessed by standardized tasks in patients with ADHD. The overall effect size (ES) was calculated as standardized mean difference (SMD) based on a random effects model.

RESULTS

Meta-analysis of five RCTs with 189 participants (mean age of 32.78 and 8.53 years in adult and child/adolescent populations, respectively) demonstrated that rTMS was more effective for improving sustained attention in patients with ADHD compared with the control groups (SMD = 0.54, p = 0.001).Our secondary analysis also showed that rTMS was more effective for improving processing speed than the control groups (SMD = 0.59, p = 0.002) but not for enhancing memory or executive function.

CONCLUSIONS

Our results supported the therapeutic efficacy of rTMS for improving sustained attention and processing speed. However, the limitation of available data warrants further studies to verify these findings.

Effects of Methylphenidate on the Dopamine Transporter and Beyond

The dopamine transporter (DAT) is the main target of methylphenidate (MPH), which remains the number one drug prescribed worldwide for the treatment of Attention-Deficit Hyperactivity Disorder (ADHD). In addition, abnormalities of the DAT have been widely associated with ADHD. Based on clinical and preclinical studies, the direction of DAT abnormalities in ADHD are, however, still unclear. Moreover, chronic treatment of MPH has been shown to increase brain DAT expression in both animals and ADHD patients, suggesting that findings of overexpressed levels of DAT in ADHD patients are possibly attributable to the effects of long-term MPH treatment rather than the pathology of the condition itself. In this chapter, we will discuss some of the effects exerted by MPH, which are related to its actions on catecholamine protein targets and brain metabolites, together with genes and proteins mediating neuronal plasticity. For this purpose, we present data from biochemical, proton nuclear magnetic resonance spectroscopy (¹H-NMR) and gene/protein expression studies. Overall, results of the studies discussed in this chapter show that MPH has a complex biological/pharmacological action well beyond the DAT.

A functional magnetic resonance imaging investigation of prefrontal cortex deep transcranial magnetic stimulation efficacy in adults with attention deficit/hyperactive disorder: A double blind, randomized clinical trial

ADHD is one of the most prevalent neurocognitive disorders. Deep Transcranial Magnetic Stimulation (dTMS) is a non-invasive neuromodulation tool that holds promise in treatment of neurocognitive disorders. Hypoactivity of the prefrontal cortex (PFC) has been observed in ADHD. This study examined the clinical, cognitive, and neural effects of dTMS to the PFC in adults with ADHD by using functional magnetic resonance imaging (fMRI). High frequency repetitive dTMS was applied to either the right or left PFC in 62 adults with ADHD in a randomized, double blind, placebo controlled protocol with 3 study groups: 2 treatment arms (rPFC, or lPFC) and a Sham arm. The study included 15 dTMS/cognitive training treatment sessions. Clinical effects were assessed with the Conners Adult ADHD Rating Scale (CAARS) self-report and the Clinical Global Impression score (CGI) as primary outcome measures. Self-report/observer questionnaires and computerized cognitive testing were also performed to assess clinical and cognitive effects. Neural effects were assessed with fMRI using working-memory (WM) and resting-state paradigms. While the study did not show improvement in the primary endpoints, significant improvements were observed in the CAARS (self-report) inattention/memory sub-scale, as well as increased activations in the rDLPFC, right parietal-cortex and right insula/IFG during WM conditions after treatment in the right stimulation group. Increased rDLPFC activation was associated with larger symptom improvement in the right stimulation group. This study indicates that dTMS is effective in modulating attention related brain networks, and is a feasible technique that may improve attention symptoms in adults with ADHD.

Quality of life in low-grade glioma patients receiving temozolomide

The purpose of this study was to describe the quality of life (QOL) of low-grade glioma (LGG) patients at baseline prior to chemotherapy and through 12 cycles of temozolomide (TMZ) chemotherapy. Patients with histologically confirmed LGG with only prior surgery were given TMZ for 12 cycles. QOL assessments by the Functional Assessment of Cancer Therapy-Brain (FACT-Br) were obtained at baseline prior to chemotherapy and at 2-month intervals while receiving TMZ. Patients with LGG at baseline prior to chemotherapy had higher reported social well-being scores (mean difference = 5.0; p < 0.01) but had lower reported emotional well-being scores (mean difference = 2.2; p < 0.01) compared to a normal population. Compared to patients with left hemisphere tumors, patients with right hemisphere tumors reported higher physical well-being scores (p = 0.01): 44% could not drive, 26% did not feel independent, and 26% were afraid of having a seizure. Difficulty with work was noted in 24%. Mean change scores at each chemotherapy cycle compared to baseline for all QOL subscales showed either no significant change or were significantly positive (p < 0.01). Patients with LGG on TMZ at baseline prior to chemotherapy reported QOL comparable to a normal population with the exception of social and emotional well-being, and those with right hemisphere tumors reported higher physical well-being scores compared to those with left hemisphere tumors. While remaining on therapy, LGG patients were able to maintain their QOL in all realms. LGG patients' QOL may be further improved by addressing their emotional well-being and their loss of independence in terms of driving or working.

The effect of brain tumour laterality on anxiety levels among neurosurgical patients

OBJECTIVES

The aim of this study was to investigate the level of anxiety in patients with a primary brain tumour and to analyse the effect of tumour laterality and histology on the level of anxiety. Recurrent measurements were assessed preoperatively, three months, and one year after operation.

METHODS

The study population consisted of 101 patients with a primary brain tumour from unselected and homogeneous population in northern Finland. The patients were studied preoperatively with CT or MRI to determine the location of the tumour. The histology of the tumour was defined according to WHO classification. The level of anxiety was obtained by Crown-Crisp Experiential Index (CCEI) scale.

RESULTS

The patients with a tumour in the right hemisphere had statistically significantly higher mean anxiety scores compared to the patients with a tumour in the left hemisphere before surgery of the tumour. By three months and by one year after surgical resection of the tumour, the level of anxiety declined in patients with a tumour in the right hemisphere. A corresponding decline was not found in patients with a tumour in the left hemisphere. According to laterality by tumour histology, the level of anxiety decreased significantly in male and female patients with a glioma in the right hemisphere, but a corresponding decline was not significant in the female patients with a meningioma in the right hemisphere. Decreased level of anxiety was not found in patients with gliomas or meningiomas in the left hemisphere by follow up measurements.

CONCLUSIONS

Primary brain tumour in right hemisphere is associated with anxiety symptoms. The laterality of anxiety seems to reflect the differentiation of the two hemispheres. The level of anxiety declined after operation of right tumour, approaching that of the general population. The effect of right hemisphere gliomas on anxiety symptoms deserves special attention in future research.

Recent developments in the application of the nonverbal learning disabilities model

Since the original work of Myklebust et al., the concept of a syndrome of nonverbal learning disabilities (NLD) has undergone considerable development and expansion, most notably in the work of Rourke. These authors have proposed a model of white matter dysfunction, predominantly in the right cerebral hemisphere, which is thought to underlie the cognitive and behavioral impairments seen in individuals with NLD. Recent research has focused on assessing the applicability of Rourke's conceptualization of the NLD syndrome and the white matter model to various neurologic, neurodevelopmental, and genetic disorders. This paper highlights recent investigations of the NLD model with respect to velocardiofacial syndrome, Klinefelter syndrome, high functioning autism, neuro-fibromatosis type I, and metachromatic leukodystrophy, and also provides a brief discussion of recent conceptualizations of the NLD model in the broader context of disorders of social and emotional functioning, and of other novel avenues of NLD research.