Depresssion, anxiety and other cognitive consequences of social isolation: Drug and non-drug treatments

Chronic cannabidiol administration modulates depressive and cognitive alterations induced by social isolation in male mice

Cannabidiol (CBD), a non-psychotropic compound derived from Cannabis sativa, is known for its potential therapeutic effects on central nervous system (CNS) disorders. This study investigates the effects of chronic CBD administration on depressive and cognitive alterations induced by social isolation in male C57BL/6 mice. The experimental design involved adult mice subjected to either group housing or 12 weeks of social isolation. Behavioral assessments, including the sucrose preference test, open field test, light/dark box, novel object recognition, and tail suspension test, were performed to evaluate the impact of CBD on emotional and cognitive alterations. Additionally, hippocampal gene expression for cannabinoid type 1 receptors (CB1R), serotonin type 1 A receptors (5HT1AR), and brain-derived neurotrophic factor (BDNF) were analyzed. Results indicate that CBD mitigated anhedonia in isolated mice and reduced immobility episodes in the TST. However, CBD did not exert significant anxiolytic effects and unexpectedly induced anxiety-like behavior in group-housed mice. The study also revealed that social isolation impaired recognition memory and reduced BDNF expression, while CBD treatment protected memory in isolated mice. These findings suggest that CBD has potential antidepressant and neuroprotective effects in social isolation-induced depressive models, although its anxiogenic effects in non-stressed mice warrant further investigation.

Differential effects of social isolation on oligodendrocyte development in different brain regions: insights from a canine model

Social isolation (SI) exerts diverse adverse effects on brain structure and function in humans. To gain an insight into the mechanisms underlying these effects, we conducted a systematic analysis of multiple brain regions from socially isolated and group-housed dogs, whose brain and behavior are similar to humans. Our transcriptomic analysis revealed reduced expression of myelin-related genes specifically in the white matter of prefrontal cortex (PFC) after SI during the juvenile stage. Despite these gene expression changes, myelin fiber organization in PFC remained unchanged. Surprisingly, we observed more mature oligodendrocytes and thicker myelin bundles in the somatosensory parietal cortex in socially isolated dogs, which may be linked to an increased expression of ADORA2A, a gene known to promote oligodendrocyte maturation. Additionally, we found a reduced expression of blood-brain barrier (BBB) structural components Aquaporin-4, Occludin, and Claudin1 in both PFC and parietal cortices, indicating BBB disruption after SI. In agreement with BBB disruption, myelin-related sphingolipids were increased in cerebrospinal fluid in the socially isolated group. These unexpected findings show that SI induces distinct alterations in oligodendrocyte development and shared disruption in BBB integrity in different cortices, demonstrating the value of dogs as a complementary animal model to uncover molecular mechanisms underlying SI-induced brain dysfunction.

Barriers and Facilitating Factors of Adherence to Antidepressant Treatments: An Exploratory Qualitative Study with Patients and Psychiatrists

This study examines the experiences and expectations of patients with depressive disorders regarding the disease and different antidepressants, as well as examining the barriers and facilitating factors that could affect their adherence to medications. An exploratory qualitative study was carried out. The study involved two focus groups made up of patients and caregivers and six semi-structured interviews with psychiatrists. In both cases, the participants were selected by intentional theoretical sampling, seeking maximum significance variation of social types. Prejudice about the side effects of medication was relevant. The importance of patients being well informed about the disease/treatments was noteworthy. The stigmatization of antidepressants by patients was identified as a barrier to medication adherence. The involvement of family members and the motivation of patients to be actively involved in the process to recover from the disease were identified as facilitating factors. The work carried out suggests the need for patients to have rigorous information about the disease/treatment to reduce the possible prejudices generated by beliefs. Maintaining greater contact and monitoring of patients/caregivers to help therapeutic adherence in patients with depressive disorders was also identified as being of great importance.

Protective Effects of Resveratrol on Adolescent Social Isolation-Induced Anxiety-Like Behaviors via Modulating Nucleus Accumbens Spine Plasticity and Mitochondrial Function in Female Rats

Social isolation (SI) is a major risk factor for mood disorders in adolescents. The nucleus accumbens (NAc) is an important reward center implicated in psychiatric disorders. Resveratrol (RSV) is one of the most effective natural polyphenols with anti-anxiety and depression effects. However, little is known about the therapeutic effects and mechanisms of RSV on behavioral abnormality of adolescent social stress. Therefore, this study aimed to investigate the underlying mechanism of RSV on the amelioration of SI-induced behavioral abnormality. We found that SI induced anxiety-like behavior and social dysfunction in isolated female rats. Moreover, SI reduced mitochondrial number and ATP levels and increased thin spine density in the NAc. RNA sequencing results showed that SI changed the transcription pattern in the NAc, including 519 upregulated genes and 610 downregulated genes, especially those related to mitochondrial function. Importantly, RSV ameliorated behavioral and spine abnormalities induced by SI and increased NAc ATP levels and mitochondria number. Furthermore, RSV increased the activity of cytochrome C oxidase (COX) and upregulated mRNA levels of Cox5a, Cox6a1 and Cox7c. These results demonstrate that the modulation of spine plasticity and mitochondrial function in the NAc by RSV has a therapeutic effect on mood disorders induced by social isolation.

Olfactory loss is a predisposing factor for depression, while olfactory enrichment is an effective treatment for depression

The loss of olfactory stimulation correlates well with at least 68 widely differing neurological disorders, including depression, and we raise the possibility that this relationship may be causal. That is, it seems possible that olfactory loss makes the brain vulnerable to expressing the symptoms of these neurological disorders, while daily olfactory enrichment may decrease the risk of expressing these symptoms. This situation resembles the cognitive reserve that is thought to protect people with Alzheimer’s neuropathology from expressing the functional deficit in memory through the cumulative effect of intellectual stimulation. These relationships also resemble the functional response of animal models of human neurological disorders to environmental enrichment, wherein the animals continue to have the induced neuropathology, but do not express the symptoms as they do in a standard environment with restricted sensorimotor stimulation.

Childhood social isolation causes anxiety-like behaviors via the damage of blood-brain barrier in amygdala in female mice

Social interaction plays an essential role in species survival for socialized animals. Previous studies have shown that a lack of social interaction such as social isolation, especially in the early-life phase, increases the risk of developing mental diseases in adulthood. Chronic social stress alters blood-brain barrier (BBB) integrity and increases peripheral cytokines to infiltrate the brain, which is linked to the development of depressive-like behaviors in mice, suggesting that BBB function is crucial in environmental stimuli-driven mood disorders via increased neuroinflammation in the brain. However, the precise mechanisms of inflammation and BBB integrity underlying the behavioral profiles induced by social isolation remain poorly understood. Here we showed that chronic childhood social isolation from post-weaning for consecutive 8 weeks in female but not male C57BL/6J mice induces anxiety-like behaviors. The levels of peripheral inflammatory cytokines including interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α in the plasma of socially isolated female mice were increased. Importantly, we found decreased expression of the endothelial cell tight junction protein Claudin-5, increased BBB breakdown and microglial activation in the amygdala of isolated but not group-housed female mice. Moreover, the neuronal activity in the amygdala was increased as evidenced by c-fos positive cells, and the levels of IL-1β in the amygdala, a critical brain region for regulating social processing and interaction, were also higher in female mice exposed to social isolation. Finally, down-regulation of Claudin-5 induced anxiety-like behaviors in group-housed females and overexpression of Claudin-5 with adeno-associated virus in the amygdala to restore BBB integrity decreased subsequent anxiety-like behaviors. Together, these findings suggest that chronic childhood social isolation impaired BBB permeability and caused neuroinflammation in the amygdala by recruiting peripheral cytokines into the brain and activating microglia, consequently triggering the development of anxiety-like behaviors in female mice.

Alone, in the dark: The extraordinary neuroethology of the solitary blind mole rat

On the social scale, the blind mole rat (BMR; Spalax ehrenbergi) is an extreme. It is exceedingly solitary, territorial, and aggressive. BMRs reside underground, in self-excavated tunnels that they rarely leave. They possess specialized sensory systems for social communication and navigation, which allow them to cope with the harsh environmental conditions underground. This review aims to present the blind mole rat as an ideal, novel neuroethological model for studying aggressive and solitary behaviors. We discuss the BMR's unique behavioral phenotype, particularly in the context of 'anti-social' behaviors, and review the available literature regarding its specialized sensory adaptations to the social and physical habitat. To date, the neurobiology of the blind mole rat remains mostly unknown and holds a promising avenue for scientific discovery. Unraveling the neural basis of the BMR's behavior, in comparison to that of social rodents, can shed important light on the underlying mechanisms of psychiatric disorders in humans, in which similar behaviors are displayed.

SARS‐CoV‐2 Omicron variant: Why global communities should take it seriously?

Introduction

In November 26th, 2021 a new strain of SARS‐CoV‐2 was designated by the World Health Organization as a variant of concern and named Omicron. The news broadcasted a global wave of panic and anxiety while many, like 2 years ago, were making themselves ready for the holiday season. After almost a month of its designation, countries from all 6 continents have been reported Omicron from their genomic sequences. This triggered an international alarm about a new era in the Covid‐19 pandemic, where despite the vast amount of vaccinations, a surge in new cases and hospitalizations are reported from all over the world.

Methods

Scientific literature published from November 26, 2021 to March 21, 2022 have been searched and retrieved by using “SARS‐COV‐2”, “Omicron”, “B.1.1.529”, “Covid‐19”, and “global community” keywords from “PubMed”, "Web o “Google Scholar”, and “MedRxiv” databases.

Results

Omicron have been evolved to spread faster than previous variants of concern, but it infects people lesser than other variants, Delta for example. Omicron can also escape vaccine‐induced immunity more than previous SARS‐CoV‐2 variants.

Discussion

Despite possible lower lethal risks than previous strains, Omicron may provide populations with a higher community transmission and a higher hospitalization load, which potentially overwhelm already exhausted health care systems. Therefore, we need to get used to the “New Normal” and maintain health recommendations to help decrease spreading of the virus and buy more time for the scientists to dive deeper into potential ways of tackling Covid‐19, more than ever.