Cortical dopamine dysregulation in schizophrenia and its link to stress

Therapeutic potential of gamma entrainment using sensory stimulation for cognitive symptoms associated with schizophrenia

Schizophrenia is a complex neuropsychiatric disorder with significant morbidity. Treatment options that address the spectrum of symptoms are limited, highlighting the need for innovative therapeutic approaches. Gamma Entrainment Using Sensory Stimulation (GENUS) is an emerging treatment for neuropsychiatric disorders that uses sensory stimulation to entrain impaired oscillatory network activity and restore brain function. Aberrant oscillatory activity often underlies the symptoms experienced by patients with schizophrenia. We propose that GENUS has therapeutic potential for schizophrenia. This paper reviews the current status of schizophrenia treatment and explores the use of sensory stimulation as an adjunctive treatment, specifically through gamma entrainment. Impaired gamma frequency entrainment is observed in patients, particularly in response to auditory and visual stimuli. Thus, sensory stimulation, such as music listening, may have therapeutic potential for individuals with schizophrenia. GENUS holds novel therapeutic potential to improve the lives of individuals with schizophrenia, but further research is required to determine the efficacy of GENUS, optimize its delivery and therapeutic window, and develop strategies for its implementation in specific patient populations.

Structural and biochemical alterations in dendritic spines as key mechanisms for severe mental illnesses

Severe mental illnesses (SMI) collectively affect approximately 20% of the global population, as estimated by the World Health Organization (WHO). Despite having diverse etiologies, clinical symptoms, and pharmacotherapies, these diseases share a common pathophysiological characteristic: the misconnection of brain areas involved in reality perception, executive control, and cognition, including the corticolimbic system. Dendritic spines play a crucial role in excitatory neurotransmission within the central nervous system. These small structures exhibit remarkable plasticity, regulated by factors such as neurotransmitter tone, neurotrophic factors, and innate immunity-related molecules, and other mechanisms - all of which are associated with the pathophysiology of SMI. However, studying dendritic spine mechanisms in both healthy and pathological conditions in patients is fraught with technical limitations. This is where animal models related to these diseases become indispensable. They have played a pivotal role in elucidating the significance of dendritic spines in SMI. In this review, the information regarding the potential role of dendritic spines in SMI was summarized, drawing from clinical and animal model reports. Also, the implications of targeting dendritic spine-related molecules for SMI treatment were explored. Specifically, our focus is on major depressive disorder and the neurodevelopmental disorders schizophrenia and autism spectrum disorder. Abundant clinical and basic research has studied the functional and structural plasticity of dendritic spines in these diseases, along with potential pharmacological targets that modulate the dynamics of these structures. These targets may be associated with the clinical efficacy of the pharmacotherapy.

Case study on the treatment of dopamine dysregulation syndrome

BACKGROUND

The clinical manifestations of Parkinson's disease (PD) are bradykinesia and abnormal walking postures. Patients with PD are prone to complications such as drug addiction, which may not only lead to cognitive, behavioral, and affective disorders but also have irreversible impacts on patients' body indexes.

CASE DESCRIPTION

In this study, the treatment regimen for a patient with dopamine dysregulation syndrome was adjusted to allow for the withdrawal of Trastal, gradual decrease of Madopar, and the addition of Comtan and clozapine. While the body indexes effectively improved, the patient did not experience negative side effects.

CONCLUSION

Reducing the dosage of Madopar and reasonably applying the treatment regimen can improve the clinical treatment effect and improve the quality of life of patients.

Increased Functional Coupling between VTA and Hippocampus during Rest in First-Episode Psychosis

Animal models suggest that interactions between the hippocampus and ventral tegmental area (VTA) underlie the onset and etiology of psychosis. While a large body of research has separately characterized alterations in hippocampal and VTA function in psychosis, alterations across the VTA and hippocampus have not been characterized in first-episode psychosis (FEP). As the phase of psychosis most proximal to conversion, studies specifically focused on FEP are valuable to psychosis research. Here, we characterize alterations in VTA-hippocampal interactions across male and female human participants experiencing their first episode of psychosis using resting state functional magnetic resonance imaging (rsfMRI). In comparison to age and sex matched healthy controls (HCs), FEP individuals had significantly greater VTA-hippocampal functional coupling but significantly less VTA-striatal functional coupling. Further, increased VTA-hippocampal functional coupling in FEP correlated with individual differences in psychosis-related symptoms. Together, these findings demonstrate alterations in mesolimbic-hippocampal circuits in FEP and extend prominent animal models of psychosis.

Fine structure analysis of perineuronal nets in the ketamine model of schizophrenia

Perineuronal nets (PNNs) represent a highly condensed specialized form of brain extracellular matrix (ECM) enwrapping mostly parvalbumin-positive interneurons in the brain in a mesh-like fashion. PNNs not only regulate the onset and completion of the critical period during postnatal brain development, control cell excitability, and synaptic transmission but are also implicated in several brain disorders including schizophrenia. Holes in the perineuronal nets, harboring the synaptic contacts, along with hole-surrounding ECM barrier can be viewed as PNN compartmentalization units that might determine the properties of synapses and heterosynaptic communication. In this study, we developed a novel open-source script for Fiji (ImageJ) to semi-automatically quantify structural alterations of PNNs such as the number of PNN units, area, mean intensity of PNN marker expression in 2D and 3D, shape parameters of PNN units in the ketamine-treated Sprague-Dawley rat model of schizophrenia using high-resolution confocal microscopic images. We discovered that the mean intensity of ECM within PNN units is inversely correlated with the area and the perimeter of the PNN holes. The intensity, size, and shape of PNN units proved to be three major principal factors to describe their variability. Ketamine-treated rats had more numerous but smaller and less circular PNN units than control rats. These parameters allowed to correctly classify individual PNNs as derived from control or ketamine-treated groups with ≈85% reliability. Thus, the proposed multidimensional analysis of PNN units provided a robust and comprehensive morphometric fingerprinting of fine ECM structure abnormalities in the experimental model of schizophrenia.

Differentiating implicit and explicit theory of mind and associated neural networks in youth at Clinical High Risk (CHR) for psychosis

BACKGROUND

Theory of mind (ToM) has been shown to be impaired in Clinical High Risk (CHR) for psychosis populations and is linked to functional outcomes and symptom severity. Implicit versus explicit ToM has seldom been differentiated in this group, and underlying neural networks have also gone unexplored.

METHODS

24 CHR and 26 healthy volunteers (HV) completed a behavioral ToM measure called the Short Story Task (SST), as well as a resting state functional MRI scan. SST performance was correlated to attenuated psychosis symptoms. Interactions between group and ToM variables (implicit, explicit, and comprehension) on global efficiency in the Mentalizing (MENT) and Mirror Neuron System (MNS) were also examined.

RESULTS

CHR individuals made significantly fewer spontaneous mental state inferences. There were trend-level associations between ToM variables and symptoms, such that greater ToM performance predicted less severe symptoms. There was an interaction of group by spontaneous mental state inference within MENT bilateral dorsomedial prefrontal cortex (dmPFC), such that CHR individuals that made spontaneous mental state inferences showed greater global efficiency within the MENT network's bilateral dmPFC.

DISCUSSION

Findings suggest implicit ToM deficits are observable prior to psychotic disorder onset, and that these deficits implicate MENT network dmPFC efficiency. Explicit ToM performance was unaltered in the CHR group, and there were no interactions observed within MNS, suggesting specificity of implicit ToM associations with MENT network dmPFC global efficiency. Results identify potential treatment targets for the neural underpinnings of ToM, thus informing prevention and intervention efforts.