Cognitive efficiency is associated with endogenous cytokine levels in patients with chronic hepatitis C

Hepatitis C Virus (HCV) Infection and Neurocognitive Impairment in Subjects with Mild Liver Disease

Hepatitis C virus (HCV) infection is a leading cause of liver cirrhosis, hepatocellular carcinoma, and liver-related deaths. It is estimated that 40-74% of patients with hepatitis C will experience at least one extrahepatic manifestation within their lifetime. The finding of HCV-RNA sequences in post-mortem brain tissue raises the possibility that HCV infection may affect the central nervous system and be the source of subtle neuropsychological symptoms, even in non-cirrhotic. Our investigation aimed to evaluate whether asymptomatic, HCV-infected subjects showed cognitive dysfunctions. Twenty-eight untreated asymptomatic HCV subjects and 18 healthy controls were tested using three neuropsychological instruments in a random sequence: Symbol Digit Modalities Test (SDMT), Controlled Oral Word Association Test (COWAT), and Continuous Visual Attention Test (CVAT). We performed depression screening, liver fibrosis assessment, blood tests, genotyping, and HCV-RNA viral load. A MANCOVA and univariate ANCOVAS were performed to examine group differences (HCV vs. healthy controls) in four scores of the CVAT (omission errors, commission errors, reaction time-RT, and variability of RT-VRT), and the scores derived from the SDMT, and the COWAT. A discriminant analysis was performed to identify which test variables effectively discriminate HCV-infected subjects from healthy controls. There were no group differences in the scores of the COWAT, SDMT, and in two variables of the CVAT (omission and commission errors). In contrast, the performance of the HCV group was poorer than the controls in RT (p = 0.047) and VRT (p = 0.046). The discriminant analysis further indicated that the RT was the most reliable variable to discriminate the two groups with an accuracy of 71.7%. The higher RT exhibited by the HCV group may reflect deficits in the intrinsic-alertness attention subdomain. As the RT variable was found to be the best discriminator between HCV patients and controls, we suggest that intrinsic-alertness deficits in HCV patients may affect the stability of response times increasing VRT and leading to significant lapses in attention. In conclusion, HCV subjects with mild disease showed deficits in RT and intraindividual VRT as compared to healthy controls.

Neuropsychological effects of direct-acting antiviral treatment for Hepatitis C virus subjects: A systematic review

Direct-acting antivirals (DAAs) have been approved in recent years to treat patients infected by the Hepatitis C virus (HCV). The DAAs treatment is well tolerated and increases sustained virological responses, but there is no consensus about the neuropsychological functioning related to the treatment. This systematic review aims to provide an overview of the recent findings exploring the cognitive effects of DAAs treatment in patients with HCV. After a systematic search on PubMed, Embase, Scopus and LILACS, studies that assessed neuropsychological data related to DAAs treatment were included. We found nine articles, considering the inclusion and exclusion criteria. Three other manuscripts were included after searching for the references listed in the previously mentioned articles. We observed methodological heterogeneity in terms of neuropsychological tests used, cognitive domain explored and the sample characteristic presented between the studies. Studies presented data from HCV subjects monoinfected with or without cirrhosis, advanced liver disease and post-transplant patients; and HCV subjects coinfected with human immunodeficiency virus (HIV). Most results from the 12 studies that explored the effect of DAAs treatment in HCV subjects' neurocognitive functioning demonstrated cognitive improvement following treatment. In general, HCV and HCV/HIV subjects improved processing speed, verbal fluency and verbal/visual episodic memory. The DAAs treatment is effective for neurocognitive functioning in HCV monoinfected and coinfected subjects, with or without advanced liver disease, since neuropsychological scores increased after treatment. Further studies, however, are needed to confirm these findings.

Serum Tumor Necrosis Factor-Alpha Levels Correlate with Cognitive Function Scales Scores in Multiple Sclerosis Patients

BACKGROUND

Cognitive dysfunction is an important feature and source of disability for patients with multiple sclerosis (MS). The correlation of cognitive function scales' scores and serum levels of the proinflammatory cytokine tumor necrosis factor-alpha (TNF-α) in MS is not well established. We aim to investigate the correlation of TNF-α serum levels with cognitive function as measured by multiple cognitive scales in patients with MS.

METHODS

Eligible sequential MS patients attending neurology clinics between October 2018 and June 2019 at King Abdulla University Hospital (KAUH) in Jordan were included. Demographic data were collected from all participants. Motor disability was measured using the Expanded Disability Status Score (EDSS), the Functional System Score (FSS), as well as the Patient Determined Disease Steps (PDDS). The Brief International Cognitive Assessment for Multiple Sclerosis (BICAMS) and the Montreal Cognitive Assessment (MOCA) were used to evaluate the cognitive status. TNF-α serum levels were measured for each patient. Correlations of TNF-α levels with cognitive function scales' scores and motor disability scores were statistically analyzed.

RESULTS

A total of 88 MS patients were included in the study. The mean age (± SD) was 35.78 (± 10.30) years, and 72.7% were females. The majority of patients (82) had relapsing multiple sclerosis (RMS). Serum TNF-α levels were significantly correlated with scores of motor disability scales in the whole patient cohort (EDSS: Pearson correlation coefficient r = 0.230, p=0.031; FSS: r = 0.260, p=0.022; and PDDS: r = 0.261, p=0.014) and in females, but not in males. In the whole cohort, the correlation between TNF-α and EDSS score was also statistically significant (r = 0.216, p=0.047) after adjustment for confounding factors including age, disease duration, and type of MS. Likewise, Serum TNF-α levels were correlated with the scores of cognitive function scales in the whole patient cohort (BICAMS: r = -0.328, p=0.002; and MOCA: r = -0.256, p=0.016). After adjusting for age, gender, education, type of MS, and EDSS score, cognitive performance was still negatively correlated with TNF-α levels (p<0.05).

CONCLUSION

Our findings confirm the presence of a significant correlation between TNF-α levels and different cognitive scales' scores in MS patients.

Relationships among neurotransmitters, cytokines and cognitive performance for individuals with hepatitis C achieving sustained virologic response: A pilot study

An important extrahepatic consequence of Hepatitis C is its adverse impact on the central nervous system and cognitive performance. We aimed to determine whether there is a significant relationship between selected neurotransmitters and cytokines and cognitive performance in patients with Chronic Hepatitis C before and after achieving sustained virologic response (SVR). Pre-SVR, elevated kynurenine was associated with increased immediate and delayed visual memory, whereas post-SVR the positive associations are between kynurenine and immediate and delayed verbal memory. TGF-B was consistently negatively associated with both immediate and delayed visual memory pre- and post-SVR. These concomitant changes may have important clinical relevance.

Cognitive impairment in HTLV-1-associated myelopathy, proviral load and inflammatory markers

OBJECTIVES

Myelopathy is a well-established long-term clinical manifestation of HTLV-1 infection. Besides motor dysfunction, cognitive impairment may be another consequence of HTLV-1 infection. Moreover, inflammatory markers may be associated with cognitive impairment in these patients. The present study compared the cognitive performance of HAM/TSP patients with healthy controls and investigated the associations between cognitive performance, proviral load and blood inflammatory markers.

METHODS

Eighty-three patients fulfilling diagnostic criteria for HAM/TSP were submitted to a comprehensive clinical, cognitive and functional evaluation, brain magnetic resonance imaging and determination of levels of IL-1β, IL-6, TNF-α, immunoglobulins and HTLV-1 proviral load in blood and cerebrospinal fluid. The control group was composed of 88 cognitively healthy subjects, matched for age, sex and educational level.

RESULTS

Compared to healthy subjects, HAM/TSP patients displayed significant global cognitive impairment and executive function deficits. HAM/TSP cognitive impairment was significantly associated with altered levels of IgM, IgG, IL-6 and TNF-α in blood. There was no association between HAM/TSP cognitive impairment and HTLV-1 proviral load.

CONCLUSIONS

This study suggests cognitive impairment may be a long-term clinical manifestation of HTLV-1 infection, which seems to be linked to the persistent inflammatory activity that is found in the disease.

Functional MRI and delay discounting in patients infected with hepatitis C

Hepatitis C virus-infected (HCV+) adults evidence increased rates of psychiatric and cognitive difficulties. This is the first study to use functional magnetic resonance imaging (fMRI) to examine brain activation in untreated HCV+ adults. To determine whether, relative to non-infected controls (CTLs), HCV+ adults exhibit differences in brain activation during a delay discounting task (DDT), a measure of one's tendency to choose smaller immediate rewards over larger delayed rewards-one aspect of impulsivity. Twenty adults with HCV and 26 CTLs completed an fMRI protocol during the DDT. Mixed effects regression analyses of hard versus easy trials of the DDT showed that, compared with CTLs, the HCV+ group exhibited less activation in the left lateral occipital gyrus, precuneus, and superior frontal gyrus. There were also significant interactive effects for hard-easy contrasts in the bilateral medial frontal gyrus, left insula, left precuneus, left inferior parietal lobule, and right temporal occipital gyrus; the CTL group evidenced a positive relationship between impulsivity and activation, while the HCV+ group exhibited a negative relationship. Within the HCV+ group, those with high viral load chose immediate rewards more often than those with low viral load, regardless of choice difficulty; those with low viral load chose immediate rewards more often on hard choices relative to easy choices. Results show that HCV+ patients exhibit greater impulsive behavior when presented with difficult choices, and impulsivity is negatively related to activation in regions important for cognitive control. Thus, interventions that decrease impulsive choice may be warranted with some HCV+ patients.

Chronic curcumin treatment improves spatial working memory but not recognition memory in middle-aged rhesus monkeys

Studies of both humans and non-human primates have demonstrated that aging is typically characterized by a decline in cognition that can occur as early as the fifth decade of life. Age-related changes in working memory are particularly evident and mediated, in part, by the prefrontal cortex, an area known to evidence age-related changes in myelin that is attributed to inflammation. In recent years, several nutraceuticals, including curcumin, by virtue of their anti-inflammatory and antioxidant effects, have received considerable attention as potential treatments for age-related cognitive decline and inflammation. Accordingly, we assessed for the first time in a non-human primate model of normal aging the efficacy of dietary intervention using the natural phenol curcumin to ameliorate the effects of aging on spatial working and recognition memory. Results revealed that monkeys receiving daily administration of curcumin over 14-18 months demonstrated a greater improvement in performance on repeated administration of a task of spatial working memory compared to monkeys that received a control substance.

Aerobic Activity in the Healthy Elderly Is Associated with Larger Plasticity in Memory Related Brain Structures and Lower Systemic Inflammation

Cognitive abilities decline over the time course of our life, a process, which may be mediated by brain atrophy and enhanced inflammatory processes. Lifestyle factors, such as regular physical activities have been shown to counteract those noxious processes and are assumed to delay or possibly even prevent pathological states, such as dementing disorders. Whereas the impact of lifestyle and immunological factors and their interactions on cognitive aging have been frequently studied, their effects on neural parameters as brain activation and functional connectivity are less well studied. Therefore, we investigated 32 healthy elderly individuals (60.4 ± 5.0 SD; range 52–71 years) with low or high level of self-reported aerobic physical activity at the time of testing. A higher compared to a lower level in aerobic physical activity was associated with an increased encoding related functional connectivity in an episodic memory network comprising mPFC, thalamus, hippocampus precuneus, and insula. Moreover, encoding related functional connectivity of this network was associated with decreased systemic inflammation, as measured by systemic levels of interleukin 6.

Deep sequencing of hepatitis C virus reveals genetic compartmentalization in cerebrospinal fluid from cognitively impaired patients

BACKGROUND & AIMS

Hepatitis C virus (HCV) causes neuropsychiatric impairment and fatigue with recent studies suggesting HCV invasion of the central nervous system (CNS). Our previous finding that endothelial cells from the blood-brain barrier support HCV infection warrants further investigation to elucidate whether the CNS can serve as a reservoir for independent HCV evolution.

METHODS

Cerebrospinal fluid (CSF) and plasma from six HCV-infected patients without liver disease or co-morbidities together with plasma from six healthy subjects were profiled for markers of immune activation and viral quasispecies measured by deep sequencing. Unsupervised data analyses were used to identify any associations between cytokine activation markers and clinical outcomes.

RESULTS

Four of six HCV-infected patients showed significant evidence of cognitive dysfunction and fatigue. Deep sequencing revealed independent viral evolution within the CNS of two cognitively impaired patients. Principal component analysis of peripheral cytokines demonstrated that individuals without cognitive impairment clustered together while a distinct cytokine pattern emerged with patients exhibiting cognitive dysfunction and fatigue.

CONCLUSIONS

Deep sequencing demonstrated unique viral variants in the CSF of two cognitively impaired patients consistent with CNS replication or sequestration. Meanwhile, compartmentalization was absent in infected patients with no neurocognitive impairment. Examination of cytokine profiles in HCV-infected patients with cognitive dysfunction revealed elevated peripheral cytokine levels resulting in a distinct cytokine profile that may be related to cognitive impairment or viral penetration into the CNS. Further studies to determine the significance of unique HCV variants within the CNS are warranted.

Effects of Viral Eradication With Ledipasvir and Sofosbuvir, With or Without Ribavirin, on Measures of Fatigue in Patients With Chronic Hepatitis C Virus Infection

BACKGROUND & AIMS

Fatigue is a disturbing symptom of chronic hepatitis C virus (HCV) infection. We assessed the effects of sustained virologic response 12 weeks after the end of therapy (SVR12) on fatigue.

METHODS

We performed a retrospective analysis of 100 patients with chronic HCV infection who achieved an SVR12 after treatment with ledipasvir and sofosbuvir, with or without ribavirin. Data were collected on fatigue-related patient-reported outcomes (PROs) and assessed by using the Functional Assessment of Cancer Therapy-Fatigue scoring system and the Vitality subscale of Short Form 36. We measured levels of cytokines and growth factors in frozen serum samples collected at baseline, week 12 of treatment, and 4 weeks after treatment. Central fatigue and peripheral or muscle fatigue (PF) were determined by using items from PROs. Serum levels of cytokines, growth factors, serotonin, alanine aminotransferase, and aspartate aminotransferase were measured by using the Bio-Plex, enzyme-linked immunosorbent, and enzymatic assays.

RESULTS

Compared with baseline, 4 weeks after the end of treatment, all fatigue-associated PROs improved significantly. Baseline PROs correlated inversely with serum level of interferon-γ; level of platelet-derived growth factor correlated with PF, central fatigue, and total fatigue score. Only PF correlated with serum level of serotonin. At baseline, high PF scores correlated with high serum levels of serotonin and low levels of interleukin-10 and tumor necrosis factor-α. In multivariate analysis, serum level of interleukin-8 was associated with greater fatigue (P < .02). Reductions in levels of chemokine (C-C motif) ligand 2 (also called monocyte chemotactic protein 1) were associated with fatigue after treatment (P = .0165).

CONCLUSIONS

In an analysis of data from patients with chronic HCV infection participating in a clinical trial of ledipasvir and sofosbuvir, SVR12 was associated with reduced fatigue, compared with baseline. High baseline serum levels of interferon-γ were associated with fatigue. Reductions in levels of chemokine (C-C motif) ligand 2 were associated with persistent fatigue after SVR12. Central and peripheral fatigue each associated with different biomarkers, suggesting different pathogenic pathways.

Cognitive function and endogenous cytokine levels in children with chronic hepatitis C

Little is known about how hepatitis C (HCV) infection affects cognitive function in children. The aim of the study was to assess the impact of HCV infection on cognitive function of children with normal liver functions and their relationships to endogenous IFN-α, IL-6 and TNF-α. IFN-α, IL-6 and TNF-α were measured and the Arabic version of the Stanford-Binet test used to assess cognitive functions in 35 children with HCV infection and 23 controls. Serum levels of IL-6 and IFN-α were significantly higher in patients compared to controls. There was a significant effect on vocabulary, comprehension, and abstract visual reasoning, quantitative reasoning and bead memory tests, as well as total short-term memory and intelligence quotient in patients compared to controls. There was a significant positive correlation between IFN-α and IL-6. Also there were significant negative correlations between IFN-α and Abstract visual reasoning test, Quantitative reasoning test, Bead memory test, Total short-term memory and Intelligence quotient; and between IL-6 and Abstract visual reasoning test, Quantitative reasoning test and Intelligence quotient. There was no significant correlation between TNF-α and any of the cognitive functions. Cytokine levels were not related to demographic characteristics of the patients or viral load (PCR). Children with chronic hepatitis C infection in its early stages showed signs of cognitive impairment, with the memory tasks being mostly affected. There was a significant correlation between endogenous cytokines and cognitive impairment in these children. Further studies are needed to define the effect of successful antiviral treatment.

A review of the neuro- and systemic inflammatory responses in post concussion symptoms: Introduction of the "post-inflammatory brain syndrome" PIBS

Post-concussion syndrome is an aggregate of symptoms that commonly present together after head injury. These symptoms, depending on definition, include headaches, dizziness, neuropsychiatric symptoms, and cognitive impairment. However, these symptoms are common, occurring frequently in non-head injured controls, leading some to question the existence of post-concussion syndrome as a unique syndrome. Therefore, some have attempted to explain post-concussion symptoms as post-traumatic stress disorder, as they share many similar symptoms and post-traumatic stress disorder does not require head injury. This explanation falls short as patients with post-concussion syndrome do not necessarily experience many key symptoms of post-traumatic stress disorder. Therefore, other explanations must be sought to explain the prevalence of post-concussion like symptoms in non-head injury patients. Many of the situations in which post-concussion syndrome like symptoms may be experienced such as infection and post-surgery are associated with systemic inflammatory responses, and even neuroinflammation. Post-concussion syndrome itself has a significant neuroinflammatory component. In this review we examine the evidence of neuroinflammation in post-concussion syndrome and the potential role systemic inflammation plays in post-concussion syndrome like symptoms. We conclude that given the overlap between these conditions and the role of inflammation in their etiologies, a new term, post-inflammatory brain syndromes (PIBS), is necessary to describe the common outcomes of many different inflammatory insults. The concept of post-concussion syndrome is in its evolution therefore, the new term post-inflammatory brain syndromes provides a better understanding of etiology of its wide-array of symptoms and the wide array of conditions they can be seen in.

Relationship between inflammation and oxidative stress and cognitive decline in the institutionalized elderly

Objective. Cognitive impairment reduces quality of life and is related to vascular and neurodegenerative disorders. However, there is also a close relationship between these diseases and oxidative stress. Thus, the purpose of this study was to assess whether inflammation and oxidative damage are associated with low cognitive performance in the elderly with different housing conditions. Methods. The study groups consisted of 32 institutionalized and 25 noninstitutionalized Brazilian elderly subjects. Oxidative damage, inflammation markers, and cognitive function were evaluated. Results. The results demonstrated pronounced oxidative stress in the institutionalized elderly group, which also had a lower antioxidant status compared to noninstitutionalized subjects. High levels of proinflammatory cytokines were also observed in the institutionalized elderly. Furthermore, the raised levels of inflammatory markers were correlated with increased oxidative stress, and both were associated with low cognitive performance. However, based on multiple linear regression analysis, oxidative stress appears to be the main factor responsible for the cognitive decline. Conclusions. The findings suggest that individuals with lower antioxidant status are more vulnerable to oxidative stress, which is associated with cognitive function, leading to reduced life quality and expectancy.

Cognitive impairment in relation to depression, anxiety and virological response in hepatitis C patients in Egypt

OBJECTIVE

Cognitive impairment commonly occurs in hepatitis C virus (HCV) patients. The objective of this study was to estimate the prevalence and sociodemographic and clinical correlates of cognitive impairment in HCV patients before and after 12 weeks of interferon treatment in comparison with a control group.

METHODS

Hundred and sixteen consecutive HCV patients were included in the study and divided into treated and untreated groups. All patients were assessed using sociodemographic and clinical questionnaire, Montreal Cognitive Assessment Scale (MOCA) and Hospital Anxiety and Depression Scale (HADS) before and after 12 weeks of treatment or observation.

RESULTS

Thirty-eight percent of treated patients showed cognitive impairment at baseline, which increased to 69% after 12 weeks of interferon treatment. This cognitive impairment was reflected in the total MOCA score and in visuo-constructional skills, attention, concentration, working memory, language, and short-term memory, which was not shown by untreated group after 12 weeks of observation. Cognitive impairment was associated with low education, but not with depression, anxiety, or virological response.

CONCLUSIONS

Cognitive impairment is common in HCV patients and increases significantly after interferon treatment. It is not related to depression or anxiety in HCV patients. Future research should focus on prevention, treatment and outcome of cognitive impairment in HCV patients, particularly those receiving interferon therapy.

Multi-analyte profile analysis of plasma immune proteins: altered expression of peripheral immune factors is associated with neuropsychiatric symptom severity in adults with and without chronic hepatitis C virus infection

BackgroundThe purpose of this study was to characterize hepatitis C virus (HCV)-associated differences in the expression of 47 inflammatory factors and to evaluate the potential role of peripheral immune activation in HCV-associated neuropsychiatric symptoms-depression, anxiety, fatigue, and pain. An additional objective was to evaluate the role of immune factor dysregulation in the expression of specific neuropsychiatric symptoms to identify biomarkers that may be relevant to the treatment of these neuropsychiatric symptoms in adults with or without HCV. MethodsBlood samples and neuropsychiatric symptom severity scales were collected from HCV-infected adults (HCV+, n = 39) and demographically similar noninfected controls (HCV-, n = 40). Multi-analyte profile analysis was used to evaluate plasma biomarkers. ResultsCompared with HCV- controls, HCV+ adults reported significantly (P < 0.050) greater depression, anxiety, fatigue, and pain, and they were more likely to present with an increased inflammatory profile as indicated by significantly higher plasma levels of 40% (19/47) of the factors assessed (21%, after correcting for multiple comparisons). Within the HCV+ group, but not within the HCV- group, an increased inflammatory profile (indicated by the number of immune factors > the LDC) significantly correlated with depression, anxiety, and pain. Within the total sample, neuropsychiatric symptom severity was significantly predicted by protein signatures consisting of 4-10 plasma immune factors; protein signatures significantly accounted for 19-40% of the variance in depression, anxiety, fatigue, and pain. ConclusionsOverall, the results demonstrate that altered expression of a network of plasma immune factors contributes to neuropsychiatric symptom severity. These findings offer new biomarkers to potentially facilitate pharmacotherapeutic development and to increase our understanding of the molecular pathways associated with neuropsychiatric symptoms in adults with or without HCV.

Neurocognitive deficits associated with the hepatitis C virus among incarcerated men

The purpose of this preliminary study was to examine cognitive functioning in inmates with the hepatitis C virus (HCV) and to investigate relationships among performance on the Repeatable Battery for the Assessment of Neuropsychological Status-Form A (RBANS; Randolph, 1998). Data from 43 HCV+ inmates were reviewed retrospectively and compared with a sample of HCV- inmates. Significant differences were found on two of five indices (Attention: U = 537.5, p = .003; r = -.32; Total: U = 643.0, p = .048; r = -.22) and four subtests: Coding (U = 326.0, p <.001, r = -.53), Digit Span (U = 634.0, p = .038, r = -.22), Story Memory (U = 625.5, p = .032, r = -.24), and Story Recall (U = 548.5, p = .004, r = -.31), with the HCV group scoring lower on all significant measures. In this study the RBANS proved to be an efficient measure with clinical utility among an HCV population. Within this incarcerated population patterns of performance were "typical" of current literature, with impaired attention appearing earlier in the disease process, and the study invites further exploration into proposed cognitive deficits among this population where HCV is highly prevalent.

Cognitive dysfunction with aging and the role of inflammation

As the average lifespan continues to climb because of advances in medical care, there is a greater need to understand the factors that contribute to quality of life in the elderly. The capacity to live independently is highly significant in this regard, but is compromised by cognitive dysfunction. Aging is associated with decreases in cognitive function, including impairments in episodic memory and executive functioning. The prefrontal cortex appears to be particularly vulnerable to the effects of advancing age. Although the mechanism of age-related cognitive decline is not yet known, age-related inflammatory changes are likely to play a role. New insights from preclinical and clinical research may give rise to novel therapeutics which may have efficacy in slowing or preventing cognitive decline with advancing age.

Butyrylcholinesterase genotype and gender influence Alzheimer's disease phenotype

Retrospective data are presented to support a spectrum of early Alzheimer's disease (AD) along a continuum defined by gender and genotype. The putative neurodegenerative mechanisms driving distinct phenotypes at each end of the spectrum are glial hypoactivity associated with early failure of synaptic cholinergic neurotransmission and glial overactivation associated with loss of neural network connectivity due to accelerated age-related breakdown of myelin. In early AD, male butyrylcholinesterase K-variant carriers with one or two apolipoprotein ɛ4 alleles have prominent medial temporal atrophy, synaptic failure, cognitive decline, and accumulation of aggregated beta-amyloid peptide. Increasing synaptic acetylcholine in damaged but still functional cholinergic synapses improves cognitive symptoms, whereas increasing the ability of glia to support synapses and to clear beta-amyloid peptide might be disease-modifying. Conversely, chronic glial overactivation can also drive degenerative processes and in butyrylcholinesterase K-variant negative females generalized glial overactivation may be the main driver from mild cognitive impairment to AD. Females are more likely than males to have accelerated age-related myelin breakdown, more widespread white matter loss, loss of neural network connectivity, whole brain atrophy, and functional decline. Increasing extracellular acetylcholine levels blocks glial activation, reduces myelin loss and damage to neural network connectivity, and is disease-modifying. Between extremes characterized by gender, genotype, and age, pathophysiology may be mixed and this spectrum may explain much of the heterogeneity of amnestic mild cognitive impairment. Preservation of the functional integrity of the neural network may be an important component of strengthening cognitive reserve and significantly delaying the onset and progression of dementia, particularly in females. Prospective confirmation of these hypotheses is required. Implications for future research and therapeutic opportunities are discussed.

Methamphetamine causes persistent immune dysregulation: a cross-species, translational report

Methamphetamine (MA) dependence causes serious cognitive impairments that can persist during abstinence and negatively affect recovery outcomes. Evidence suggests that immune factors, such as cytokines, chemokines, and cellular adhesion molecules, contribute to MA-induced immune dysfunction, neuronal injury, and persistent cognitive impairments, yet the role of MA-induced brain inflammation remains unclear. To address this question, we used a cross-species, translational approach. Thirty-two male C57BL/6J mice were administered MA (1 mg/kg) or saline subcutaneously for seven consecutive days. Mice were euthanized at 72 h or 3 weeks after the last drug dose, and blood and brain samples were collected. In addition, 20 adults in remission from MA dependence and 20 non-dependent controls completed neuropsychological assessments and a blood draw. Multiplex assays were used to measure cytokine, chemokine, and intercellular adhesion molecule (ICAM-1) expression in mouse and human samples. A number of significant MA-induced changes in neuroimmune factors were observed. Of particular interest were the chemokine monocyte chemoattractant protein 1 (MCP-1) and the cellular adhesion molecule ICAM-1, which were similarly increased in the plasma of MA exposed mice as well as humans. In human participants, MA-induced changes in the cytokine and chemokine milieu were accompanied by increased cognitive impairments. Mice showing MA-induced changes in peripheral immune molecule expression also had significant brain-region specific changes in pro-inflammatory cytokines, chemokines, and ICAM-1. This cross-species, translational study suggests that chronic CNS immune dysregulation may in part contribute to the longlasting neuropsychiatric consequences of MA dependence.

Parallel declines in cognition, motivation, and locomotion in aging mice: association with immune gene upregulation in the medial prefrontal cortex

Aging in humans is associated with parallel changes in cognition, motivation, and motoric performance. Based on the human aging literature, we hypothesized that this constellation of age-related changes is mediated by the medial prefrontal cortex and that it would be observed in aging mice. Toward this end, we performed detailed assessments of cognition, motivation, and motoric behavior in aging mice. We assessed behavioral and cognitive performance in C57Bl/6 mice aged 6, 18, and 24 months, and followed this with microarray analysis of tissue from the medial prefrontal cortex and analysis of serum cytokine levels. Multivariate modeling of these data suggested that the age-related changes in cognition, motivation, motor performance, and prefrontal immune gene expression were highly correlated. Peripheral cytokine levels were also correlated with these variables, but less strongly than measures of prefrontal immune gene upregulation. To determine whether the observed immune gene expression changes were due to prefrontal microglial cells, we isolated CD11b-positive cells from the prefrontal cortex and subject them to next-generation RNA sequencing. Many of the immune changes present in whole medial prefrontal cortex were enriched in this cell population. These data suggest that, as in humans, cognition, motivation, and motoric performance in the mouse change together with age and are strongly associated with CNS immune gene upregulation.