Anhedonia in cocaine use disorder is associated with inflammatory gene expression

Cocaine Destroys Gray Matter Brain Cells and Accelerates Brain Aging

Introduction: Cocaine use disorder (CUD) is a substance use disorder characterized by a strong desire to obtain, consume, and misuse cocaine. Little is known about how cocaine affects the structure of the brain. In this study, we first investigated the anatomical brain changes in individuals with CUD compared to their matched healthy controls, and then explored whether these anatomical brain abnormalities contribute to considerably accelerated brain aging among this population. Methods: At the first stage, we used anatomical magnetic resonance imaging (MRI) data, voxel-based morphometry (VBM), and deformation-based morphometry techniques to uncover the morphological and macroscopic anatomical brain changes in 74 CUD patients compared to 62 age- and sex-matched healthy controls (HCs) obtained from the SUDMEX CONN dataset, the Mexican MRI dataset of patients with CUD. Then, we computed brain-predicted age difference (i.e., brain-PAD: the brain-predicted age minus the actual age) in CUD and HC groups using a robust brain age estimation framework. Using a multiple regression analysis, we also investigated the regional gray matter (GM) and white matter (WM) changes associated with the brain-PAD. Results: Using a whole-brain VBM analysis, we observed widespread gray matter atrophy in CUD patients located in the temporal lobe, frontal lobe, insula, middle frontal gyrus, superior frontal gyrus, rectal gyrus, and limbic lobe regions compared to the HCs. In contrast, we did not observe any swelling in the GM, changes in the WM, or local brain tissue atrophy or expansion between the CUD and HC groups. Furthermore, we found a significantly higher brain-PAD in CUD patients compared to matched HCs (mean difference = 2.62 years, Cohen's d = 0.54; t-test = 3.16, p = 0.002). The regression analysis showed significant negative changes in GM volume associated with brain-PAD in the CUD group, particularly in the limbic lobe, subcallosal gyrus, cingulate gyrus, and anterior cingulate regions. Discussion: The results of our investigation reveal that chronic cocaine use is linked to significant changes in gray matter, which hasten the process of structural brain aging in individuals who use the drug. These findings offer valuable insights into the impact of cocaine on the composition of the brain.

Interaction between maternal immune activation and peripubertal stress in rats: impact on cocaine addiction-like behaviour, morphofunctional brain parameters and striatal transcriptome

Substance use disorders are more prevalent in schizophrenia, but the causal links between both conditions remain unclear. Maternal immune activation (MIA) is associated with schizophrenia which may be triggered by stressful experiences during adolescence. Therefore, we used a double-hit rat model, combining MIA and peripubertal stress (PUS), to study cocaine addiction and the underlying neurobehavioural alterations. We injected lipopolysaccharide or saline on gestational days 15 and 16 to Sprague-Dawley dams. Their male offspring underwent five episodes of unpredictable stress every other day from postnatal day 28 to 38. When animals reached adulthood, we studied cocaine addiction-like behaviour, impulsivity, Pavlovian and instrumental conditioning, and several aspects of brain structure and function by MRI, PET and RNAseq. MIA facilitated the acquisition of cocaine self-administration and increased the motivation for the drug; however, PUS reduced cocaine intake, an effect that was reversed in MIA + PUS rats. We found concomitant brain alterations: MIA + PUS altered the structure and function of the dorsal striatum, increasing its volume and interfering with glutamatergic dynamics (PUS decreased the levels of NAA + NAAG but only in LPS animals) and modulated specific genes that could account for the restoration of cocaine intake such as the pentraxin family. On its own, PUS reduced hippocampal volume and hyperactivated the dorsal subiculum, also having a profound effect on the dorsal striatal transcriptome. However, these effects were obliterated when PUS occurred in animals with MIA experience. Our results describe an unprecedented interplay between MIA and stress on neurodevelopment and the susceptibility to cocaine addiction.

The impacts of anhedonia on brain functional alterations in patients with major depressive disorder: A resting-state functional magnetic resonance imaging study of regional homogeneity

BACKGROUND

Anhedonia, as one of the core manifestations of major depressive disorder (MDD), has an effect on prognosis of the disease. However, the neuropathology of MDD is complex and the neural basis of anhedonia remains unclear. The aim of the present study was to investigate the impacts of anhedonia on brain functional alterations in patients with MDD.

METHODS

A total of 62 individuals including MDD patients with anhedonia (n = 22), MDD patients without anhedonia (n = 20), and healthy controls (HCs, n = 20) were recruited. All participants underwent resting-state functional magnetic resonance imaging scanning and intrinsic brain function was explored by using regional homogeneity (ReHo) method. A two-sample t-test was performed to explore ReHo differences between MDD patients and HCs, then analysis of variance (ANOVA) was introduced to obtain brain regions with significant differences among three groups, and finally post hoc tests were calculated for inter-group comparisons. Correlations between ReHo values of each survived area and clinical characteristics in MDD patients were further analyzed.

RESULTS

Compared with HCs, MDD showed increased ReHo in the left superior temporal gyrus (STG) and bilateral inferior frontal gyrus (IFG), as well as decreased ReHo in the left superior frontal gyrus (SFG). Interestingly, this relationship was attenuated and no longer significant after consideration for the effect of anhedonia in MDD patients. MDD patients with anhedonia were more likely to exhibit decreased ReHo in the left SFG and left middle cingulate gyrus (MCG) when comparing to HCs. No significant difference was found between MDD patients without anhedonia and HCs, either the two groups of MDD patients. There was no significant association between ReHo values of each survived area and clinical characteristics in MDD patients.

CONCLUSIONS

The present results suggest that the impacts of anhedonia on brain functional alterations in MDD should be emphasized and disturbed intrinsic brain function in the frontal-limbic regions may be associated with anhedonia in MDD patients.

Mass Spectrometry-Based Proteome Profiling of Extracellular Vesicles Derived from the Cerebrospinal Fluid of Adult Rhesus Monkeys Exposed to Cocaine throughout Gestation

Cocaine use disorder has been reported to cause transgenerational effects. However, due to the lack of standardized biomarkers, the effects of cocaine use during pregnancy on postnatal development and long-term neurobiological and behavioral outcomes have not been investigated thoroughly. Therefore, in this study, we examined extracellular vesicles (EVs) in adult (~12 years old) female and male rhesus monkeys prenatally exposed to cocaine (n = 11) and controls (n = 9). EVs were isolated from the cerebrospinal fluid (CSF) and characterized for the surface expression of specific tetraspanins, concentration (particles/mL), size distribution, and cargo proteins by mass spectrometry (MS). Transmission electron microscopy following immunogold labeling for tetraspanins (CD63, CD9, and CD81) confirmed the successful isolation of EVs. Nanoparticle tracking analyses showed that the majority of the particles were <200 nm in size, suggesting an enrichment for small EVs (sEV). Interestingly, the prenatally cocaine-exposed group showed ~54% less EV concentration in CSF compared to the control group. For each group, MS analyses identified a number of proteins loaded in CSF-EVs, many of which are commonly listed in the ExoCarta database. Ingenuity pathway analysis (IPA) demonstrated the association of cargo EV proteins with canonical pathways, diseases and disorders, upstream regulators, and top enriched network. Lastly, significantly altered proteins between groups were similarly characterized by IPA, suggesting that prenatal cocaine exposure could be potentially associated with long-term neuroinflammation and risk for neurodegenerative diseases. Overall, these results indicate that CSF-EVs could potentially serve as biomarkers to assess the transgenerational adverse effects due to prenatal cocaine exposure.

Increased plasma levels of IL-6 are associated with striatal structural atrophy in major depressive disorder patients with anhedonia

BACKGROUND

Anhedonia, as the core endophenotype of major depressive disorder (MDD), is closely related to poor prognosis, but the mechanism of this feature remains to be understood. The aim of this study was to investigate the inflammatory factors and brain structural alterations in MDD patients with anhedonia and evaluate the relationship between these factors.

METHODS

We assessed the plasma levels of interleukin-1 beta (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) in MDD patients with anhedonia (n = 22), MDD patients without anhedonia (n = 20), and age- and sex-matched healthy controls (HCs, n = 20) by enzyme-linked immunosorbent assay kits. All participants underwent high-resolution brain magnetic resonance imaging (MRI) scans, and voxel-based morphometry (VBM) was used to evaluate their gray matter volume (GMV). We compared inflammatory factors and GMV among the three groups and explored their relationships in MDD patients with anhedonia.

RESULTS

Compared with those of HCs, plasma levels of IL-1β were increased in patients with MDD independent of anhedonia features, while plasma levels of IL-6 were elevated in MDD patients with anhedonia only. Meanwhile, MDD patients with anhedonia exhibited reduced GMV in the left striatal structures compared to MDD patients without anhedonia and HCs. Moreover, a significant association was observed between increased plasma levels of IL-6 and decreased GMV of the left putamen in MDD patients with anhedonia.

CONCLUSIONS

The present research outcomes suggest that anhedonia is associated with increased plasma levels of IL-6 and decreased GMV in the left striatal structures. In addition, this study demonstrates that GMV loss in the left putamen is related to increased plasma levels of IL-6 in MDD with anhedonia, which provides further insights into the possible mechanisms of anhedonia.

Genetics of substance use disorders in the era of big data

Substance use disorders (SUDs) are conditions in which the use of legal or illegal substances, such as nicotine, alcohol or opioids, results in clinical and functional impairment. SUDs and, more generally, substance use are genetically complex traits that are enormously costly on an individual and societal basis. The past few years have seen remarkable progress in our understanding of the genetics, and therefore the biology, of substance use and abuse. Various studies - including of well-defined phenotypes in deeply phenotyped samples, as well as broadly defined phenotypes in meta-analysis and biobank samples - have revealed multiple risk loci for these common traits. A key emerging insight from this work establishes a biological and genetic distinction between quantity and/or frequency measures of substance use (which may involve low levels of use without dependence), versus symptoms related to physical dependence.

Inflammatory cytokines, complement factor H and anhedonia in drug-naïve major depressive disorder

OBJECTIVE

Anhedonia is a core symptom of major depressive disorder (MDD) and often associated with poor prognosis. The main objective of the present study was to explore the relationship between complement factor H (CFH), inflammatory cytokines and anhedonia in drug-naïve MDD patients.

METHODS

A total of 215 participants (61 MDD patients with anhedonia, 78 MDD patients without anhedonia, and 76 control subjects) were included. Severity of depression and levels of anhedonia were evaluated by Hamilton Rating Scale for Depression-17 (HAMD-17) and SHAPS (Snaith-Hamilton Pleasure Scale). Plasma levels of CFH, interleukin-6 (IL-6), IL-10 and tumor necrosis factor-α (TNF-α) were measured.

RESULTS

The plasma levels of CFH, IL-10 and TNF-α were higher in drug-naïve MDD patients than control subjects. Compared to MDD patients without anhedonia, patients with anhedonia showed higher levels of CFH and IL-6. The stepwise regression analysis revealed that IL-10, TNF-α, as well as IL-10 × TNF-α were associated with depressive symptoms measured by HAMD-17 in drug-naïve MDD patients, while only CFH levels were identified as a mediator factor for the severity of anhedonia in the patients.

CONCLUSION

MDD patients with anhedonia showed different inflammatory characteristics compared to patients without anhedonia. Our results provide novel evidence suggesting that increased plasma CFH levels may be a potential biomarker of anhedonia of subtyping MDD.

Peripheral blood microRNA levels in females with cocaine use disorder

BACKGROUND

There is growing emphasis in the field of psychiatry on the need to identify candidate biomarkers to aid in diagnosis and clinical management of addictive disorders. MicroRNAs (miRNAs) are small nucleotide sequences with the ability to regulate gene expression at the transcriptomic level. However, the role of miRNAs as potential biomarkers for addiction is still underexplored. Based on translational and clinical findings, we compared the expression levels of microRNA-124 (miR-124), microRNA-181 (miR-181), and microRNA-212 (miR-212) between a group of females with cocaine use disorder (CUD; n = 30) and a group of healthy female controls (HC; n = 20).

METHODS

Blood expression levels of miR-124, miR-181, and miR-212 in the HC and CUD group were determined by qPCR, using two miRNAs as endogenous controls (miR-24 and miR-126). Substance use behavior was assessed by self-report using the Addiction Severity Index (ASI-6) and depressive symptoms severity was measured using the Beck Depressive Inventory (BDI-II). Urine screen test was performed to detect cocaine metabolites.

RESULTS

Mir-124 and miR-181 were upregulated in the CUD group (p > 0.01). Furthermore, increased cognitive/affective depression symptoms were identified among a CUD subgroup with the higher miR-181 expression levels (p > 0.05). No significant difference in expression levels was found for miR-212.

CONCLUSIONS

MiR-124 and miR-181 show promise as biomarkers for CUD when assessed in the peripheral blood. Further investigation is needed to elucidate the molecular mechanisms underlying these associations and to validate target genes regulated by these miRNAs.