Structural and Functional Consequences of Hypercortisolism on Brain: Are the Brain and Psycho-neuro-cognitive Manifestations Reversible?

Using hypnotic suggestion in the rehabilitation of working memory capacity after acquired brain injury: study protocol for a randomized controlled trial

OBJECTIVES

Establishment of effective evidence-based interventions in rehabilitation of working memory (WM) deficits after acquired brain injury (ABI) is sorely needed. Despite robust evidence for the efficiency of clinical hypnosis in a wide range of clinical conditions, and improved understanding of mechanisms underlying its effects, the potential of clinical hypnosis in cognitive rehabilitation is underexplored. A recent study has shown large effects of hypnotic suggestion on WM capacity following ABI. This randomized controlled trial aims to evaluate and explore the replicability of these findings and examine the generalization of treatment effects. The study will also explore possible mechanisms of change.

METHODS

Ninety patients will be recruited from the Sunnaas Rehabilitation Hospital. Inclusion criteria are nonprogressive ABI, minimum 12-month post-injury, ongoing WM deficits, and age between 18 and 67 years. Patients will be randomized to either (a) an intervention group receiving four weekly 1-h sessions with induction and hypnosis, (b) an active control group receiving four weekly 1-h sessions of induction and mindfulness, or (c) a passive control group without intervention. The targeted procedure consists of suggestions about enhancing WM functions, for example through the instantiation of preinjury WM capacity in the present using age regression or through visualizations of brain plasticity. The non-targeted suggestions contain no explicit mention of ABI- or WM-related abilities. Each participant will be assessed at baseline, immediately after intervention, and 6 months after baseline. The primary outcome is the WM index from WAIS-IV and self- and informant-reported WM subscale from BRIEF-A, a questionnaire exploring executive functioning in everyday life. Secondary outcomes include a cognitive composite score derived from tests measuring processing speed, executive functions, learning capacity and memory, and self-reported measures of emotional distress, quality of life, and community integration. Exploratory measures include self-rated ABI and WM-related self-efficacy.

DISCUSSION

Rehabilitation of impaired WM after ABI has hitherto yielded limited transfer effects beyond the training material, i.e., improvement effects on everyday WM capacity, and clinical trials of new interventions are thus warranted. Long-standing empirical evidence demonstrates that hypnosis is an effective therapeutic technique in a wide range of conditions, and recent exploratory research has suggested a high efficacy of hypnosis in improving WM capacity in patients with ABI. However, these extraordinary findings need replication in studies applying scientifically rigorous designs. If successful, our ambition is to provide recommendations and materials to implement hypnotic suggestion as an adjunct treatment following ABI. Study findings may inform future studies exploring the use of clinical hypnosis in other areas of rehabilitation, such as mild TBI, and in other neurological conditions where WM deficit is prominent.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05287542. Registered on March 2022 PROTOCOL VERSION: Protocol version 2.0, December 2023.

Glymphatic transport is reduced in rats with spontaneous pituitary tumor

Background and objective

Pituitary tumor in patients induces adverse alterations in the brain, accompanied by cognitive deficits. Dysfunction of glymphatic waste clearance results in accumulation of neurotoxic products within the brain, leading to cognitive impairment. However, the status of glymphatic function in the brain with pituitary tumor is unknown. Using magnetic resonance imaging (MRI) and an advanced mathematical modeling, we investigated the changes of glymphatic transport in the rats carrying spontaneous pituitary tumor.

Methods

Rats (22-24 months, female, Wistar) with and without pituitary tumor (n = 7/per group) underwent the identical experimental protocol. MRI measurements, including T2-weighted imaging and dynamic 3D T1-weighted imaging with intracisternal administration of contrast agent, were performed on each animal. The contrast-induced enhancement in the circle of Willis and in the glymphatic influx nodes were observed on the dynamic images and verified with time-signal-curves (TSCs). Model-derived parameters of infusion rate and clearance rate that characterize the kinetics of glymphatic tracer transport were evaluated in multiple representative brain regions.

Results

Our imaging data demonstrated a higher incidence of partially enhanced circle of Willis (86 vs. 14%; p < 0.033) and a lower incidence of enhancement in glymphatic influx nodes of pituitary (71 vs. 100%) and pineal (57 vs. 86%) recesses in the rats with pituitary tumor than in the rats with normal appearance of pituitary gland, indicating an intensification of impaired peri-vascular pathway and impeded glymphatic transport due to the presence of pituitary tumor. Consistently, our kinetic modeling and regional cerebral tissue quantification revealed significantly lower infusion and clearance rates in all examined regions in rats with spontaneous pituitary tumor than in non-tumor rats, representing a suppressed glymphatic transport in the brain with pituitary tumor.

Conclusion

Our study demonstrates the compromised glymphatic transport in the rat brain with spontaneous pituitary tumor. The reduced efficiency in cerebral waste clearance increases the risk for neurodegeneration in the brain that may underlie the cognitive impairment commonly seen in patients with pituitary tumors.

General additive models address statistical issues in diffusion MRI: An example with clinically anxious adolescents

Statistical models employed to test for group differences in quantized diffusion-weighted MRI white matter tracts often fail to account for the large number of data points per tract in addition to the distribution, type, and interdependence of the data. To address these issues, we propose the use of Generalized Additive Models (GAMs) and supply code and examples to aid in their implementation. Specifically, using diffusion data from 73 periadolescent clinically anxious and no-psychiatric-diagnosis control participants, we tested for group tract differences and show that a GAM allows for the identification of differences within a tract while accounting for the nature of the data as well as covariates and group factors. Further, we then used these tract differences to investigate their association with performance on a memory test. When comparing our high versus low anxiety groups, we observed a positive association between the left uncinate fasciculus and memory overgeneralization for negatively valenced stimuli. This same association was not evident in the right uncinate or anterior forceps. These findings illustrate that GAMs are well-suited for modeling diffusion data while accounting for various aspects of the data, and suggest that the adoption of GAMs will be a powerful investigatory tool for diffusion-weighted analyses.