Brain Sciences

Background and Objectives: Obesity has been associated with structural brain alterations and an increased long-term risk of cognitive decline; however, the regional distribution and tissue specificity of these changes remain inconsistent across neuroimaging studies. This study investigated global and regional brain volume differences in neurologically asymptomatic and cognitively preserved adults with obesity using automated artificial intelligence-based MRI volumetric analysis. Materials and Methods: This cross-sectional study included 100 adults, comprising 50 participants with obesity (body mass index (BMI) ≥ 30 kg/m²) and 50 adults with normal-weight considered as controls (BMI 18.5–24.9 kg/m²) matched for age and sex. All participants underwent standardized brain MRI on the same 1.5 T scanner, including a high-resolution 3D T1-weighted sequence. Brain segmentation and volumetric analysis were performed using AIRS Medical SwiftSight-Brain. Primary analyses used volumes normalized to total intracranial volume (TIV). Group differences were evaluated using effect-size estimates and linear models adjusted for age and sex; exploratory region-of-interest analyses were corrected for multiple comparisons. Results: Participants with obesity had lower cerebral white matter volume than controls (29.43 ± 1.80% vs. 30.21 ± 1.21% TIV; p = 0.014; Hedges’ g = −0.50), and the difference remained significant after adjustment for age and sex (β = −0.768 percentage points, 95% CI −1.368 to −0.167; p = 0.013). Regionally, temporal white matter (4.69 ± 0.31% vs. 4.86 ± 0.23% TIV; adjusted p = 0.0018), parietal white matter (7.09 ± 0.48% vs. 7.34 ± 0.36% TIV; adjusted p = 0.0045), and cerebellar white matter (1.70 ± 0.13% vs. 1.77 ± 0.13% TIV; adjusted p = 0.009) were lower in the obesity group. Whole-brain/TIV was also lower after age and sex adjustment (β = −0.907 percentage points; 95% CI −1.655 to −0.158; p = 0.018), whereas cortical gray matter volume was virtually identical between groups (p = 0.960). No significant difference in hippocampal volume was observed. Conclusions: Neurologically asymptomatic and cognitively preserved adults with obesity exhibited subtle, regionally selective brain volume differences, with the most pronounced alterations involving cerebral white matter, particularly of temporal and parietal lobes. These findings suggest that obesity-related brain vulnerability may be detectable before clinically manifest cognitive impairment and may preferentially involve white matter rather than widespread cortical gray matter loss.

Background/Objectives: Virtual reality (VR) is increasingly being incorporated into neurorehabilitation to support functional training and participation in meaningful activities. However, the characteristics of VR interventions involving occupational therapists remain insufficiently described. This scoping review aimed to describe VR interventions involving occupational therapists for adults with neurological conditions. Methods: A scoping review was conducted following the PRISMA-ScR guidance. A systematic search was performed in PubMed, Scopus, Web of Science, Embase and CENTRAL. Randomized controlled trials and quasi-experimental studies examining VR interventions for adults with neurological conditions and involving at least one occupational therapist were included. Study selection and data charting were independently performed by two reviewers. Results: Seventy-one studies were included, of which 58 were randomized controlled trials. Most studies included 50 participants or fewer (n = 62), and the median study-level age was 58.6 years. Stroke was the neurological condition investigated exclusively in most studies (n = 60), and motor, sensory, and other body-function outcomes were the most frequently assessed (n = 65). Activities of daily living (ADL) and occupational performance were assessed in 48 studies, whereas participation was assessed in only 6. Interventions lasted a median of 4.8 weeks and non-immersive VR predominated (n = 62). Occupational therapists were most commonly involved in intervention or rehabilitation delivery, supervision, or configuration. Conclusions: VR interventions involving occupational therapists were predominantly non-immersive, focused on adults with stroke, with occupational therapist involvement most often comprising direct intervention or rehabilitation delivery, supervision, or configuration. Outcomes mainly addressed motor, sensory, and other body functions and ADL/occupational performance, while participation was rarely assessed, highlighting important gaps for future research. Future studies should broaden the range of technologies and neurological conditions, place greater emphasis on participation, and report the specific role of occupational therapists more clearly.

Inhibitory neurotransmission in the adult hippocampus is essential for regulating excitatory activity, synchronizing neuronal firing, and supporting cognitive function and emotional states. Brain damage such as traumatic brain injury (TBI) and ischemia disrupt this finely tuned inhibition, leading to excitation–inhibition imbalance further and pathological hyperexcitability. Here we review the populations of hippocampal inhibitory neurons, as well as the molecular and network-level alterations in inhibitory circuits following hippocampal damage. We detail how inhibitory neurotransmission progresses from acute synaptic dysfunction and interneuron vulnerability to chronic maladaptive remodeling and altered inhibitory signaling through time. These dynamic changes contribute to persistent network instability and cognitive deficits as well as emotional alterations. Understanding the temporal dynamics of inhibitory reorganization provides critical insights into mechanisms underlying post-injury hyperexcitability and identifies potential targets for therapeutic intervention aimed at restoring inhibitory control and hippocampal circuit function.