Interplay Between the Immune and Nervous Cognitive Systems in Homeostasis and in Malaria.

The immune and nervous systems can be thought of as cognitive and plastic systems, since they are both involved in cognition/recognition processes and can be architecturally and functionally modified by experience, and such changes can influence each other's functioning. The immune system can affect nervous system function depending on the nature of the immune stimuli and the pro/anti-inflammatory responses they generate. Here we consider interactions between the immune and nervous systems in homeostasis and disease, including the beneficial and deleterious effects of immune stimuli on brain function and the impact of severe and non-severe malaria parasite infections on neurocognitive and behavioral parameters in human and experimental murine malaria. We also discuss the effect of immunization on the reversal of cognitive deficits associated with experimental non-severe malaria in a model susceptible to the development of the cerebral form of the illness. Finally, we consider the possibility of using human vaccines, largely exploited as immune-prophylactics for infectious diseases, as therapeutic tools to prevent or mitigate the expression of cognitive deficits in infectious and chronic degenerative diseases.

Long-term effect of uncomplicated Plasmodium berghei ANKA malaria on memory and anxiety-like behaviour in C57BL/6 mice.

BACKGROUND: Cerebral malaria, the main complication of Plasmodium falciparum infection in humans, is associated with persistent neurocognitive sequels both in human disease and the murine experimental model. In recent years, cognitive deficits related to uncomplicated (non-cerebral) malaria have also been reported in chronically exposed residents of endemic areas, but not in some murine experimental models of non-cerebral malaria. This study aimed at evaluating the influence of uncomplicated malaria on different behavioural paradigms associated with memory and anxiety-like parameters in a murine model that has the ability to develop cerebral malaria. METHODS: Plasmodium berghei ANKA-infected and non-infected C57BL/6 mice were used. Development of cerebral malaria was prevented by chloroquine treatment starting on the fourth day of infection. The control group (non-infected mice) were treated with PBS. The effect of uncomplicated malaria infection on locomotor habituation, short and long-term memory and anxious-like behaviour was evaluated 64 days after parasite clearance in assays including open field, object recognition, Y-maze and light/dark tasks. RESULTS: Plasmodium berghei ANKA-infected mice showed significant long-lasting disturbances reflected by a long-term memory-related behaviour on open field and object recognition tasks, accompanied by an anxious-like phenotype availed on open field and light-dark tasks. CONCLUSIONS: Long-term neurocognitive sequels may follow an uncomplicated malaria episode in an experimental model prone to develop cerebral malaria, even if the infection is treated before the appearance of clinical signs of cerebral impairment.

Measuring the Effect of Soil-Transmitted Helminth Infections on Cognitive Function in Children: Systematic Review and Critical Appraisal of Evidence.

Recently the role of soil-transmitted helminth (STH) infections in children's cognitive developmental impairment has been under scrutiny. We conducted a systematic review of the evidence for associations between STH infections and cognitive function of children using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol. We aimed to identify the domains of cognitive function in three age strata (<24months, 24-59months and ≥60months) and critically appraise the general design protocol of the studies, with a focus on the cognitive function measurement tools used. A total of 42 papers fulfilled the inclusion criteria, including 10 studies from a recent Cochrane review. Our findings demonstrate variation in tested domains, lack of consistency in the use of measurement tools and analysis of results. Cognitive function measures in children aged under 59months have been mainly limited to domains of gross motor, fine motor and language skills, whereas in children aged 60months and above most studies tested domains such as memory and processing speed. Even within the same age group the results on the association between STH infections and measures of cognitive development were often conflicting. The current study highlights the need for methodological consensus in the use of measurement tools and data analysis protocols if the effect of STH infections on cognitive function domains in children is to be correctly established. This will be an imperative next step to generate conclusive evidence of the role of STH infections in cognitive development in children.

Cognitive performance of children living in endemic areas for Plasmodium vivax.

BACKGROUND: The role of repeated episodes of malaria on the cognitive development of children is a relevant issue in endemic areas since it can have a long-lasting impact on individual lifespan. The aim of the current paper was to investigate whether the history of malaria can impair the verbal and performance skills of children living in an endemic area with low transmission of Plasmodium vivax malaria. METHODS: A cross-sectional study was conducted with children living in an endemic area of P. vivax malaria in Brazilian Amazon basin. The history of episodes of malaria was used as criteria for inclusion of children in the groups. The cognitive performance was assessed by the Wechsler intelligence scale for children-III edition (WISC-III), which was applied to the participants of study by two trained psychologists. RESULTS: A total of 17 cases and 26 controls was included in the study. A significant low score of verbal quotient was found in the cases (p = 0.005), however, the performance IQ was similar in both groups (p = 0.304). The full-scale IQ was significantly lower in the cases when compared to the controls (p = 0.042). The factorials index showed significant difference only in the subtest of verbal comprehension with the lower values in the cases (p = 0.0382), compared to the controls. The perceptual organization (p = 0.363), freedom from distractability (p = 0.180) and processing speed (p = 0.132) were similar in both groups. CONCLUSIONS: Children with a history of vivax malaria has a significant impairment of verbal and full-scale quotients as well as a significant low index of verbal comprehension. These findings are likely due to the absenteeism caused by malaria and by the low parental education, which impairs an adequate response to the environmental stimulus.

[Rehabilitation treatment in child and youth patients with acquired brain injury]. / Tratamiento rehabilitador en el paciente infantojuvenil con daño cerebral adquirido.

Brain injury is one of the most frequent causes of death and disability in the child and adolescent. The improvement in patient care in the acute moment and the evolution of health care has meant and increase in the survival of these patients and also of the sequelae. Physical, cognitive-behavioral or organic symptoms are usually. The second is being one of the most frequent and most limiting in these patients. The brain injury affects the patient but involves the whole family because of the disability and the dependence it entails. The team is multidisciplinary and the rehabilitation physician performs the coordination functions. The family should receive assistance from the first day and are an important part in the proper evolution of patients. The treatment must be individualized and adapted for each patient and usually last between 6 and 18 months.

TITLE: Tratamiento rehabilitador en el paciente infantojuvenil con daño cerebral adquirido.El daño cerebral es una de las causas mas frecuentes de muerte y discapacidad en la poblacion infantojuvenil. La mejoria en la atencion a los pacientes en el momento agudo y la evolucion de la asistencia sanitaria han supuesto un aumento de la supervivencia de estos pacientes y tambien de las secuelas. Secuelas fisicas, cognitivo-conductuales u organicas son frecuentes, y las segundas son unas de las mas frecuentes y mas limitantes en estos pacientes. El daño cerebral afecta al paciente, pero involucra a toda la familia por la discapacidad que implica y por la dependencia que conlleva. El equipo es multidisciplinar, y el medico rehabilitador hace las funciones de coordinacion. La familia debe recibir asistencia desde el primer dia y es parte importante en la evolucion adecuada de los pacientes. El tratamiento debe ser individualizado y adaptado para cada paciente, y suele durar entre 6 y 18 meses.

Elevated cerebrospinal fluid tumour necrosis factor is associated with acute and long-term neurocognitive impairment in cerebral malaria.

Systemic tumour necrosis factor-α (TNF-α) may contribute to the pathogenesis of cerebral malaria (CM) by promoting endothelial activation and parasite sequestration. However, less is known about the role of central nervous system (CNS) TNF-α in CM. We assessed plasma (n=249) and cerebrospinal fluid (CSF) (n=167) TNF-α levels in Ugandan children with CM, plasma TNF-α in Ugandan community control children (n=198) and CSF TNF-α in North American control children who had recovered from leukaemia (n=13). Plasma and CSF TNF-α were measured by magnetic bead assay. We compared plasma and CSF TNF-α levels in children with CM to mortality, acute and chronic neurologic deficits and long-term neurocognitive impairment. Plasma and CSF TNF-α levels were higher in CM than control children (P<.0001 for both). CSF TNF-α levels were higher in children who had neurologic deficits at discharge or 6-month follow-up (P≤.05 for both). Elevated CSF but not plasma TNF-α was associated with longer coma duration (Spearman's rho .18, P=.02) and deficits in overall cognition in children 5 years and older (ß coefficient -.74, 95% CI -1.35 to -0.13, P=.02). The study findings suggest that CNS TNF-α may be involved in the development of acute and chronic neurologic and cognitive sequelae in children with CM.

Optimal trajectories of brain state transitions.

The complexity of neural dynamics stems in part from the complexity of the underlying anatomy. Yet how white matter structure constrains how the brain transitions from one cognitive state to another remains unknown. Here we address this question by drawing on recent advances in network control theory to model the underlying mechanisms of brain state transitions as elicited by the collective control of region sets. We find that previously identified attention and executive control systems are poised to affect a broad array of state transitions that cannot easily be classified by traditional engineering-based notions of control. This theoretical versatility comes with a vulnerability to injury. In patients with mild traumatic brain injury, we observe a loss of specificity in putative control processes, suggesting greater susceptibility to neurophysiological noise. These results offer fundamental insights into the mechanisms driving brain state transitions in healthy cognition and their alteration following injury.

Nerolidol-loaded nanospheres prevent behavioral impairment via ameliorating Na+, K+-ATPase and AChE activities as well as reducing oxidative stress in the brain of Trypanosoma evansi-infected mice.

The aim of this study was to investigate the effect of nerolidol-loaded nanospheres (N-NS) on the treatment of memory impairment caused by Trypanosoma evansi in mice, as well as oxidative stress, and Na+, K+-ATPase and acetylcholinesterase (AChE) activities in brain tissue. Animals were submitted to behavioral tasks (inhibitory avoidance task and open-field test) 4 days postinfection (PI). Reactive oxygen species (ROS) and thiobarbituric acid-reactive substance (TBARS) levels and catalase (CAT), superoxide dismutase (SOD), Na+, K+-ATPase and AChE activities were measured on the fifth-day PI. T. evansi-infected mice showed memory deficit, increased ROS and TBARS levels and SOD and AChE activities, and decreased CAT and Na+, K+-ATPase activities compared to uninfected mice. N-NS prevented memory impairment and oxidative stress parameters (except SOD activity), while free nerolidol (N-F) restored only CAT activity. Also, N-NS treatment was able to prevent alterations in Na+, K+-ATPase and AChE activities caused by T. evansi infection. A significantly negative correlation was observed between memory and ROS production (p < 0.001; r = -0.941), as well as between memory and AChE activity (p < 0.05; r = -0.774). On the contrary, a significantly positive correlation between memory and Na+, K+-ATPase activity was observed (p < 0.01; r = 0.844). In conclusion, N-NS was able to reverse memory impairment and to prevent increased ROS and TBARS levels due to amelioration of Na+, K+-ATPase and AChE activities and to activation of the antioxidant enzymes, respectively. These results suggest that N-NS treatment may be a useful strategy to treat memory dysfunction and oxidative stress caused by T. evansi infection.

Early and long-term outcome of infants born extremely preterm.

There is no question that birth at extremely low gestational ages presents a significant threat to an infant's survival, health and development. Growing evidence suggests that gestational age may be conceptualised as a continuum in which births before 28 weeks of gestation (extremely preterm: EP) represent the severe end of a spectrum of health and developmental adversity. Although comprising just 1%-2% of all births, EP deliveries pose the greatest challenge to neonatal medicine and to health, education and social services for the provision of ongoing support for survivors with additional needs. Studying the outcomes of these infants remains critical for evaluating and enhancing clinical care, planning long-term support and for advancing our understanding of the life-course consequences of immaturity at birth. Here we review literature relating to early and long-term neurodevelopmental, cognitive, behavioural and educational outcomes following EP birth focusing on key themes and considering implications for intervention.

Infectious disease burden and cognitive function in young to middle-aged adults.

Prior research has suggested an association between exposure to infectious disease and neurocognitive function in humans. While most of these studies have explored individual viral, bacterial, and even parasitic sources of infection, few have considered the potential neurocognitive burden associated with multiple infections. In this study, we utilized publically available data from a large dataset produced by the Centers for Disease Control and Prevention that included measures of neurocognitive function, sociodemographic variables, and serum antibody data for several infectious diseases. Specifically, immunoglobulin G antibodies for toxocariasis, toxoplasmosis, hepatitis A, hepatitis B, and hepatitis C, cytomegalovirus, and herpes 1 and 2 were available in 5662 subjects. We calculated an overall index of infectious-disease burden to determine if an aggregate measure of exposure to infectious disease would be associated with neurocognitive function in adults aged 20-59 years. The index predicted processing speed and learning and memory but not reaction time after controlling for age, sex, race-ethnicity, immigration status, education, and the poverty-to-income ratio. Interactions between the infectious-disease index and some sociodemographic variables were also associated with neurocognitive function. In summary, an index aggregating exposure to several infectious diseases was associated with neurocognitive function in young- to middle-aged adults.

Got worms? Perinatal exposure to helminths prevents persistent immune sensitization and cognitive dysfunction induced by early-life infection.

The incidence of autoimmune and inflammatory diseases has risen dramatically in post-industrial societies. "Biome depletion" - loss of commensal microbial and multicellular organisms such as helminths (intestinal worms) that profoundly modulate the immune system - may contribute to these increases. Hyperimmune-associated disorders also affect the brain, especially neurodevelopment, and increasing evidence links early-life infection to cognitive and neurodevelopmental disorders. We have demonstrated previously that rats infected with bacteria as newborns display life-long vulnerabilities to cognitive dysfunction, a vulnerability that is specifically linked to long-term hypersensitivity of microglial cell function, the resident immune cells of the brain. Here, we demonstrate that helminth colonization of pregnant dams attenuated the exaggerated brain cytokine response of their offspring to bacterial infection, and that combined with post-weaning colonization of offspring with helminths (consistent with their mothers treatment) completely prevented enduring microglial sensitization and cognitive dysfunction in adulthood. Importantly, helminths had no overt impact on adaptive immune cell subsets, whereas exaggerated innate inflammatory responses in splenic macrophages were prevented. Finally, helminths altered the effect of neonatal infection on the gut microbiome; neonatal infection with Escherichia coli caused a shift from genera within the Actinobacteria and Tenericutes phyla to genera in the Bacteroidetes phylum in rats not colonized with helminths, but helminths attenuated this effect. In sum, these data point toward an inter-relatedness of various components of the biome, and suggest potential mechanisms by which this helminth might exert therapeutic benefits in the treatment of neuroinflammatory and cognitive disorders.

Prediction of Alzheimer's Disease Dementia: Data from the GuidAge Prevention Trial.

In therapeutic trials, it is crucial to identify Alzheimer's disease (AD) at its prodromal stage. We assessed the accuracy of the free and cued selective reminding test (FCSRT) compared to other cognitive tests to predict AD dementia in subjects with subjective cognitive decline or mild cognitive impairment. Subjects from the placebo group of the GuidAge trial over 70 years old and without clinical signs of dementia at baseline who completed the 5-year follow-up free of dementia (n = 840) or developed AD dementia (n = 73) were included in our study. Among all the tests, the sum of the 3 free recall of the FCSRT (FCSRT-FR) and the sum of free and cued recall (FCSRT-TR) yielded the best results to predict AD dementia occurrence (all p values <0.05 for comparison of FCSRT-FR ROC and MMSE, CDRsb, and CVF ROCs). FCSRT-FR had an area under the ROC curve of 0.799 (95% CI 0.738-0.85) and the optimal cut-off was 20 (se 68.06% , sp 81.43% , PPV 23.90% , NPV 96,75%). Concerning FCSRT-TR, the AUC was 0.776 and the optimal cut-off was 42 (se 62.5% , sp 82.26% , PPV 23.20% and NPV 96.24%). This study sets the framework for implementing the FCSRT in clinical and therapeutic trials for efficient subject selection.

Interaction between Helicobacter pylori and latent toxoplasmosis and demographic variables on cognitive function in young to middle-aged adults.

Helicobacter pylori and latent toxoplasmosis are widespread diseases that have been associated with cognitive deficits and Alzheimer's disease. We sought to determine whether interactions between Helicobacter pylori and latent toxoplasmosis, age, race-ethnicity, educational attainment, economic status, and general health predict cognitive function in young and middle-aged adults. To do so, we used multivariable regression and multivariate models to analyze data obtained from the United States' National Health and Nutrition Examination Survey from the Centers for Disease Control and Prevention, which can be weighted to represent the US population. In this sample, we found that 31.6 percent of women and 36.2 percent of men of the overall sample had IgG Antibodies against Helicobacter pylori, although the seroprevalence of Helicobacter pylori varied with sociodemographic variables. There were no main effects for Helicobacter pylori or latent toxoplasmosis for any of the cognitive measures in models adjusting for age, sex, race-ethnicity, educational attainment, economic standing, and self-rated health predicting cognitive function. However, interactions between Helicobacter pylori and race-ethnicity, educational attainment, latent toxoplasmosis in the fully adjusted models predicted cognitive function. People seropositive for both Helicobacter pylori and latent toxoplasmosis - both of which appear to be common in the general population - appear to be more susceptible to cognitive deficits than are people seropositive for either Helicobacter pylori and or latent toxoplasmosis alone, suggesting a synergistic effect between these two infectious diseases on cognition in young to middle-aged adults.

Cognitive and behaviour dysfunction of children with neurocysticercosis: a cross-sectional study.

Eighty-three confirmed cases of neurocysticercosis diagnosed as per modified delBrutto criteria were enrolled in the study (Group-I) to observe cognitive and behavioural changes. Controls consisted of two groups: children with idiopathic generalized tonic-clonic seizure (Group-II) and normal children with non-specific cough (Group-III). Cases and controls were subjected to cognitive and behaviour assessment. There was significant difference in the intelligence quotient (IQ) of cases in domains of visual perception, immediate recall, analysis synthesis and reasoning, verbal ability, memory and spatial ability. In the age group of 6-18 years, cases had significantly more behaviour problems than control without seizure, in domains of anxious depressed, withdrawn depressed, somatic problems, social problems and rule-breaking behaviour. Neurocysticercosis causes decline in cognitive function and behaviours in older children, which should be recognized early for appropriate management and to avoid undue parental anxiety.

Cerebral malaria retinopathy predictors of persisting neurocognitive outcomes in Malawian children.

BACKGROUND: Neuropsychological sequelae from pediatric cerebral malaria (CM) have been well-documented. Although malaria-specific retinopathy during acute illness has become a defining criterion for CM, its relationship to neurocognitive sequelae has not been documented. This relationship is important if malaria-specific retinopathy reflects the possible brain neuropathogenesis leading to long-term neurocognitive deficits. METHODS: From 2008 to 2012, 49 Malawian children 4.5-12 years of age surviving retinopathy-positive CM (CM-R) were tested 1-6 yrs after illness with the Kaufman Assessment Battery for Children, 2 edition, the tests of variables of attention and the Achenbach Child Behavior Checklist. In an observational study of a cohort of cerebral malaria survivors, these neurocognitive and behavioral outcomes were statistically related to types and severity of retinopathy measures, while controlling for age, sex, body mass index, socioeconomic status and time interval between illness and testing. RESULTS: Worse scores for hemorrhages, papilledema, optic disk hyperemia, retinal whitening of macula and foveal annulus were associated with poorer Kaufman Assessment Battery for Children, 2 edition mental processing index and global scale scores. Disk hyperemia was also predictive of tests of variables of attention D prime overall attention performance (inattention) and commission errors (impulsivity). Few associations were found between retinopathy scores and Achenbach Child Behavior Checklist (emotional and behavioral) outcomes. CONCLUSIONS: We are the first to report the relationship between severity of malaria-specific retinopathy during acute illness in CM survivors and persisting neurocognitive problems. These findings support earlier studies documenting that severity of retinopathy during acute illness is medically prognostic in CM survivors. We extend these findings to include long-term neurocognitive outcomes.

Measuring the positive and negative aspects of the caring role in community versus aged care setting.

AIM: To investigate the positive and negative aspects of family caregiving in two settings: community and aged care facility. METHODS: Postal questionnaires included the short Zarit Burden Interview (ZBI) and a scale developed for this study: Positive Aspects of Caring Scale (PACS). RESULTS: Analysis of responses of 90 carers showed high burden levels, with no difference between care settings. Carers of an older person with a cognitive condition showed higher burden. There was no association between carer burden and positive attitudes. Carers in community settings recorded lower levels of positive attitudes. CONCLUSION: The two measures (ZBI and PACS) may be a useful clinical tool to provide a balanced assessment of carers' experiences. The high burden found in both carer groups indicates the need for greater awareness, and improved support for carers, across the care continuum, from home to aged care facility.

Neurocognitive sequelae of cerebral malaria in adults: a pilot study in Benguela Central Hospital, Angola.

OBJECTIVE: To characterize the neurocognitive sequelae of cerebral malaria (CM) in an adult sample of the city of Benguela, Angola. METHODS: A neuropsychological assessment was carried out in 22 subjects with prior history of CM ranging from 6 to 12 months after the infection. The obtained results were compared to a control group with no previous history of cerebral malaria. The study was conducted in Benguela Central Hospital, Angola in 2011. RESULTS: CM group obtained lower results on the two last trials of a verbal learning task and on an abstract reasoning test. CONCLUSIONS: CM is associated to a slower verbal learning rate and to difficulties in the ability to discriminate and perceive relations between new elements.

Asymptomatic Plasmodium infection and cognition among primary schoolchildren in a high malaria transmission setting in Uganda.

Asymptomatic parasitemia is common among schoolchildren living in areas of high malaria transmission, yet little is known about its effect on cognitive function in these settings. To investigate associations between asymptomatic parasitemia, anemia, and cognition among primary schoolchildren living in a high malaria transmission setting, we studied 740 children enrolled in a clinical trial in Tororo, Uganda. Parasitemia, measured by thick blood smears, was present in 30% of the children. Infected children had lower test scores for abstract reasoning (adjusted mean difference [AMD] -0.6, 95% confidence interval [CI] -1.01 to -0.21) and sustained attention (AMD -1.6 95% CI -2.40 to -0.81) compared with uninfected children. There was also evidence for a dose-response relationship between parasite density and scores for sustained attention. No associations were observed between anemia and either test of cognition. Schoolchildren in high transmission settings may experience cognitive benefits, from interventions aimed at reducing the prevalence of asymptomatic parasitemia.

Extra-intestinal and long term consequences of Giardia duodenalis infections.

Giardiasis is the most common waterborne parasitic infection of the human intestine worldwide. The etiological agent, Giardia duodenalis (syn. G. intestinalis, G. lamblia), is a flagellated, binucleated protozoan parasite which infects a wide array of mammalian hosts. Human giardiasis is a true cosmopolitan pathogen, with highest prevalence in developing countries. Giardiasis can present with a broad range of clinical manifestations from asymptomatic, to acute or chronic diarrheal disease associated with abdominal pain and nausea. Most infections are self-limiting, although re-infection and chronic infection can occur. Recent evidence indicating that Giardia may cause chronic post-infectious gastrointestinal complications have made it a topic of intense research. The causes of the post-infectious clinical manifestations due to Giardia, even after complete elimination of the parasite, remain obscure. This review offers a state-of-the-art discussion on the long-term consequences of Giardia infections, from extra-intestinal manifestations, growth and cognitive deficiencies, to post-infectious irritable bowel syndrome. The discussion also sheds light on some of the novel mechanisms recently implicated in the production of these post-infectious manifestations.