Higher Cerebrospinal Fluid Soluble Urokinase-type Plasminogen Activator Receptor, But Not Interferon γ-inducible Protein 10, Correlate With Higher Working Memory Deficits

BACKGROUND

We hypothesized that the induction of monocyte activation biomarkers, especially soluble urokinase-type plasminogen activator receptor (suPAR) and interferon γ-inducible protein 10 (IP-10), is lower in HIV-1C than HIV-1B, owing to a defective Tat cysteine dimotif (C30S).

METHODS

A total of 68 paired cerebrospinal fluid (CSF) and blood samples from people with HIV (PWH), free of CNS opportunistic infections, from a Southern Brazil outpatient HIV clinic were evaluated such as HIV-1B subtype (n = 27), HIV-1C (n = 26), other (n = 15), and 19 HIV-negative controls. The levels of suPAR, IP-10, neopterin, and β2 microglobulin (β2m) in the CSF and serum were quantified using different immunoassays.

RESULTS

Overall, in PWH, increases in CSF suPAR, CSF/serum suPAR, and CSF/serum β2m correlated with worse working memory deficits (r = 0.303, 0.353, and 0.289, respectively, all P < 0.05). The medians of IP-10, suPAR, neopterin, and β2m in CSF and serum and the CSF/serum ratio and suPAR index were comparable between the HIV-1B and HIV-1C subtypes. CSF IP-10 and neopterin and serum IP-10 and suPAR levels were higher in PWH than the HIV-negative controls (P = 0.015, P = 0.001, P < 0.0001, and P < 0.001, respectively). The serum β2m level was higher in HIV-associated dementia than neuropsychologically normal or asymptomatic (P = 0.024).

DISCUSSION

We observed that higher levels of CSF suPAR and the suPAR quotient correlated with worse working memory deficit. Elevated levels of monocyte activation were similar in both HIV-1 B and C subtypes, providing no evidence of reduced neuropathogenicity of HIV-1 subtype C Tat compared with subtype B.

Preliminary comparative study of cortical thickness in HIV-infected patients with and without working memory deficit

Purpose

Changes in cerebral cortical regions occur in HIV-infected patients, even in those with mild neurocognitive disorders. Working memory / attention is one of the most affected cognitive domain in these patients, worsening their quality of life. Our objective was to assess whether cortical thickness differs between HIV-infected patients with and without working memory deficit.

Methods

Forty-one adult HIV-infected patients with and without working memory deficit were imaged on a 1.5 T scanner. Working memory deficit was classified by composite Z scores for performance on the Digits and Letter-Number Sequencing subtests of the Wechsler Adult Intelligence Scale (third edition; WAIS-III). Cortical thickness was determined using FreeSurfer software. Differences in mean cortical thickness between groups, corrected for multiple comparisons using Monte-Carlo simulation, were examined using the query design estimate contrast tool of the FreeSurfer software.

Results

Greater cortical thickness in left pars opercularis of the inferior frontal gyrus, and rostral and caudal portions of the left middle frontal gyrus (cluster 1; p = .004), and left superior frontal gyrus (cluster 2; p = .004) was observed in HIV-infected patients with working memory deficit compared with those without such deficit. Negative correlations were found between WAIS-III–based Z scores and cortical thickness in the two clusters (cluster 1: ρ = –0.59; cluster 2: ρ = –0.47).

Conclusion

HIV-infected patients with working memory deficit have regions of greater thickness in the left frontal cortices compared with those without such deficit, which may reflect increased synaptic contacts and/or an inflammatory response related to the damage caused by HIV infection.

Neuropsychological and psychiatric outcomes in encephalitis: A multi-centre case-control study

Objectives

Our aim was to compare neuropsychological and psychiatric outcomes across three encephalitis aetiological groups: Herpes simplex virus (HSV), other infections or autoimmune causes (Other), and encephalitis of unknown cause (Unknown).

Methods

Patients recruited from NHS hospitals underwent neuropsychological and psychiatric assessment in the short-term (4 months post-discharge), medium-term (9–12 months after the first assessment), and long-term (>1-year). Healthy control subjects were recruited from the general population and completed the same assessments.

Results

Patients with HSV were most severely impaired on anterograde and retrograde memory tasks. In the short-term, they also showed executive, IQ, and naming deficits, which resolved in the long-term. Patients with Other or Unknown causes of encephalitis showed moderate memory impairments, but no significant impairment on executive tests. Memory impairment was associated with hippocampal/medial temporal damage on magnetic resonance imaging (MRI), and naming impairment with left temporal and left frontal abnormalities. Patients reported more subjective cognitive complaints than healthy controls, with tiredness a significant problem, and there were high rates of depression and anxiety in the HSV and the Other encephalitis groups. These subjective, self-reported complaints, depression, and anxiety persisted even after objectively measured neuropsychological performance had improved.

Conclusions

Neuropsychological and psychiatric outcomes after encephalitis vary according to aetiology. Memory and naming are severely affected in HSV, and less so in other forms. Neuropsychological functioning improves over time, particularly in those with more severe short-term impairments, but subjective cognitive complaints, depression, and anxiety persist, and should be addressed in rehabilitation programmes.

Zika Virus Infection in Hypothalamus Causes Hormone Deficiencies and Leads to Irreversible Growth Delay and Memory Impairment in Mice

Zika virus (ZIKV) can cause microcephaly in the fetus. However, its effects on body growth and the development of children with postnatal ZIKV infection are largely unknown. To examine this, we intraperitoneally challenged mouse pups with ZIKV. Infection causes an irreversible growth delay and deficits in spatial learning and memory, with growth-relevant hormones significantly reduced during infection. These effects are associated with ZIKV RNA expression in the hypothalamus, blood, and brain but not in the pituitary and thyroid. Infection is also associated with hypothalamic inflammation, and ZIKV antigen is detectable in neuroendocrine cells producing thyrotropin-releasing hormone. Moreover, early administration of growth hormone could significantly improve growth delay. Our results demonstrate that ZIKV can infect the hypothalamus, causing multi-hormone deficiencies and delayed growth and development in a mouse model. Therefore, prospective multidisciplinary follow-up of ZIKV-infected children may be necessary to understand potential effects of this virus on childhood development.

Neurological Complications of Ebola Virus Infection

Ebola virus disease is one of the deadliest pathogens known to man, with a mortality rate between 25-90% depending on the species and outbreak of Ebola. Typically, it presents with fever, headache, voluminous vomiting and diarrhea, and can progress to a hemorrhagic illness; neurologic symptoms, including meningoencephalitis, seizures, and coma, can also occur. Recently, an outbreak occurred in West Africa, affecting > 28,000 people, and killing > 11,000. Owing to the magnitude of this outbreak, and the large number (>17,000) of Ebola survivors, the medical and scientific communities are learning much more about the acute manifestations and sequelae of Ebola. A number of neurologic complications can occur after Ebola, such as seizures, memory loss, headaches, cranial nerve abnormalities, and tremor. Ebola may also persist in some immunologically privileged sites, including the central nervous system, and can rarely lead to relapse in disease. Owing to these findings, it is important that survivors are evaluated and monitored for neurologic symptoms. Much is unknown about this disease, and treatment remains largely supportive; however, with ongoing clinical and basic science, the mechanisms of how Ebola affects the central nervous system and how it persists after acute disease will hopefully become more clear, and better treatments and clinical practices for Ebola patients will be developed.

A new model for CD8+ T cell memory inflation based upon a recombinant adenoviral vector

CD8(+) T cell memory inflation, first described in murine CMV (MCMV) infection, is characterized by the accumulation of high-frequency, functional Ag-specific CD8(+) T cell pools with an effector-memory phenotype and enrichment in peripheral organs. Although persistence of Ag is considered essential, the rules underpinning memory inflation are still unclear. The MCMV model is, however, complicated by the virus's low-level persistence and stochastic reactivation. We developed a new model of memory inflation based on a β-galactosidase (βgal)-recombinant adenovirus vector. After i.v. administration in C57BL/6 mice, we observed marked memory inflation in the βgal96 epitope, whereas a second epitope, βgal497, undergoes classical memory formation. The inflationary T cell responses show kinetics, distribution, phenotype, and functions similar to those seen in MCMV and are reproduced using alternative routes of administration. Memory inflation in this model is dependent on MHC class II. As in MCMV, only the inflating epitope showed immunoproteasome independence. These data define a new model for memory inflation, which is fully replication independent, internally controlled, and reproduces the key immunologic features of the CD8(+) T cell response. This model provides insight into the mechanisms responsible for memory inflation and, because it is based on a vaccine vector, also is relevant to novel T cell-inducing vaccines in humans.

A diffusion tensor imaging and neuropsychological study of prospective memory impairment in South African HIV positive individuals

HIV-associated prospective memory (ProM) impairment has emerged, in earlier studies as a significant predictor of medication management and independence in activities of daily living. The relationship between ProM and white matter integrity in HIV has not previously been investigated. Participants, including 128 HIV-infected individuals and 32 healthy controls, were assessed using a comprehensive neuropsychological evaluation and both objective and subjective measures of ProM. Diffusion tensor imaging (DTI) was utilized to investigate the relationship of white matter integrity to ProM in a randomly selected subsample of 40 HIV positive subjects, using a whole brain voxel-based approach to define fractional anisotrophy (FA) and mean diffusion (MD). Total prospective memory was significantly poorer in the HIV positive group when compared with healthy controls (p = 0.023). Time-based ProM was poorer in the HIV group compared to healthy controls both without prompts (p = 0.001) and with prompts (p = 0.001). Poor Total ProM score correlated with performance on neuropsychological tests of executive functioning, information processing speed, learning, and working memory (p < 0.05). Those HIV positive participants with poor ProM had significantly decreased FA in the regions of superior corona radiata (p = 0.0035), the corpus collosum (p = 0.006) and the cingulum (p = 0.0033) when compared to those who were HIV positive with good ProM. This study reinforces the importance of ProM assessment in HIV.

Disturbance in cerebral spinal fluid sphingolipid content is associated with memory impairment in subjects infected with the human immunodeficiency virus

Despite widespread use of antiretroviral therapies to control replication of the human immunodeficiency virus (HIV), dysfunctions of cognition that are collectively termed HIV-associated neurocognitive disorders (HAND) still occur in approximately 50% of those infected by the virus. Currently there is not a biomarker that can identify HIV-infected people who are at risk for the development of HAND. Previous studies have identified particular sphingolipid species that are dysregulated in HAND, but the neurocognitive correlates of these biochemical findings are not currently understood. To address this question, we compared cerebrospinal fluid (CSF) levels of sphingomyelin, ceramide, and sterol species with performance on standard neurological tests designed to assess the function of multiple cognitive and motor domains in HIV-infected subjects. We found that sphingomyelin:ceramide ratios for acyl chain lengths of C16:0, C18:0, C22:0, and C24:0 were associated with worse performance on several indices of memory. The most striking finding was for the acyl chain of C18:0 that consistently associated with performance on multiple tests of memory. These findings suggest that the sphingomyelin:ceramide ratio for C18:0 may be a reasonable surrogate marker for memory dysfunction in HIV-infected subjects.

HIV-associated prospective memory impairment in the laboratory predicts failures on a semi-naturalistic measure of health care compliance

HIV-associated neurocognitive impairment, particularly in the domain of prospective memory (ProM), increases the risk of poor everyday functioning outcomes, including medication non-adherence. However, whether ProM plays a role in health care compliance outside of the realm of medication adherence remains to be determined. This study evaluated the hypothesis that ProM is an independent predictor of failure to comply with non-medication-related instructions akin to those commonly given by health care providers. Participants were 139 HIV-infected adults who underwent medical, psychiatric, and neuropsychological assessments, including a laboratory-based measure of ProM. To assess real-world compliance, participants were instructed to call the examiner 24 hours after the evaluation and report how many hours they had slept. Individuals who failed to correctly comply with these instructions (n = 104) demonstrated significantly lower performance on both time- and event-based ProM at baseline than the compliant group (n = 35), an effect that was primarily driven by errors of omission. ProM remained a significant predictor of noncompliance after controlling for potential confounders, including demographics (e.g., education), traditional cognitive measures of retrospective memory and executive functions, and psychiatric factors (e.g., depression). Results support the hypothesis that ProM plays a unique role in compliance with health care instructions for HIV disease management and may inform interventions designed to improve treatment outcomes.

[Impaired cognitive function in hepatitis C virus infection]

Impaired cognitive function is commonly seen in patients with hepatitis C-virus (HCV). This might be due to a toxic effect of the virus itself or to neuroinflammatory processes with a direct damaging cerebral effect. The symptoms appear in the pre-cirrhotic stage and impair the patient's level of functioning. Therefore, doctors in contact with HCV patients should be up to date on the existing knowledge in the field to be able to inform patients about their cognitive deficits and take them into consideration. It is unknown if the cognitive deficits decline when the virus is eradicated.

Impairments in memory and hippocampal function in HIV-positive vs HIV-negative women: a preliminary study

OBJECTIVE

Neurocognitive studies of HIV typically target executive functions dependent on frontostriatal circuitry. The integrity of medial temporal systems has received considerably less attention despite high hippocampal viral load. Studies also predominately involve HIV+ men, though HIV+ women may be at increased risk for cognitive dysfunction due to the high prevalence of psychosocial/mental health problems and lower educational attainment. Our aim was to conduct a preliminary investigation of episodic memory and its neural correlates in HIV-infected and at-risk uninfected women.

METHODS

Participants included 54 HIV+ and 12 HIV- women (mean age = 43 years; 86% African American) recruited from the Chicago site of the Women's Interagency HIV Study. Participants completed standardized tests of verbal and visual episodic memory, working memory, and executive function. A subset of 11 women also underwent functional MRI during a delayed verbal episodic memory task.

RESULTS

HIV serostatus predicted significantly lower immediate and delayed verbal episodic memory, working memory, and visual memory. Preliminary neuroimaging findings revealed group differences in bilateral hippocampal function, with HIV+ women showing decreased activation during encoding and increased activation during delayed recognition. These alterations correlated with worse episodic verbal memory.

CONCLUSIONS

Verbal episodic memory deficits are evident in HIV+ women and may be associated with hippocampal dysfunction at both encoding and retrieval.

Changes in neuronal protein expression in LP-BM5-infected mice

Murine acquired immunodeficiency syndrome (MAIDS) induced by LP-BM5 murine leukemia virus is used as a model of human immunodeficiency virus (HIV)-related neurologic dysfunction. Mice infected with LP-BM5 have mnemonic abnormalities (i.e., spontaneous alternation behavior in the Y-maze and performance in the Morris water maze) and biochemical alternations (i.e., cytokines, platelet-activating factor, quinolinate, glutamate and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor) that produce neurologic symptoms similar to those observed in HIV-related neurologic dysfunction. To identify proteins associated with dysmnesia in the MAIDS model, we examined the expression of neuronal proteins in LP-BM5-infected mice using two-dimensional polyacrylamide gel electrophoresis (2-DE). Neuronal protein expression in LP-BM5-infected mice was compared with that in non-infected mice using the Image Master 2D. We detected approximately 800 protein spots, of which 35 were distinguishable between non-infected and LP-BM5-infected mice. Most of these spots were downregulated in LP-BM5-infected mice. Three of the spots were identified as 14-3-3 protein zeta/delta, synapsin 2 and protein disulfide isomerase using a capillary nanoliquid chromatography tandem mass spectrometric system. We verified the expression levels of these proteins by Western blot. Analysis of these 35 spots could provide insight into mechanisms of dysmnesia in the MAIDS model of HIV-related neuronal dysfunction.

Disrupted spatial memory is a consequence of picornavirus infection

Picornaviruses are a socioeconomically important family of viruses that includes the rhinoviruses and enteroviruses. Many of these viruses, including the "common cold" Coxsackie virus A21, maintain neurovirulent potential and may induce hippocampal injury. The behavioral implications of this injury have not been adequately explored. Using C57BL/6J mice infected with Theiler's murine encephalomyelitis virus, we examined the formation of spatial memories using the Morris water maze test. Virus-infected mice had greater search error compared to sham-infected animals during the location of a hidden platform and were unable to discriminate the location of the training quadrant during the final probe trial. Furthermore, sham-infected mice were place responders whereas virus-infected mice were cue responders, indicating a lack of spatial memory formation in infected animals. Importantly, the degree of memory impairment was correlated to the extent of hippocampal injury. This suggests that picornavirus infection of the human CNS may also result in at least some degree of neurologic deficit. An important implication of such subclinical virus-induced neurologic deficit is that the injury may accumulate over the lifetime of the individual, eventually leading to the manifestation of clinical cognitive or memory deficits.

Altered hippocampal-prefrontal activation in HIV patients during episodic memory encoding

OBJECTIVE

To investigate the integrity of hippocampal-prefrontal circuitry during episodic encoding in patients with HIV.

METHODS

Functional MRI was used to observe changes in blood oxygenation level-dependent (BOLD) signal in 14 HIV-positive participants and 14 age- and education-matched control subjects while performing an episodic encoding task. Subjects also completed neuropsychological measures of attention and memory.

RESULTS

Behavioral results revealed no significant differences in neuropsychological performance. The fMRI results revealed that while both groups recruited brain regions known to be important for successful encoding, including bilateral medial temporal lobes and inferior prefrontal gyri, the HIV group demonstrated significantly reduced signal intensity changes in the right posterior hippocampus, right inferior frontal gyrus, and left lingual gyrus. Additionally, the HIV group exhibited more activity within lateral frontal and posterior parietal regions.

CONCLUSIONS

This study demonstrates altered integrity of hippocampal-prefrontal regions during episodic encoding in HIV-positive patients. These results extend previous studies that have documented the effects of HIV on fronto-striatal circuits, and suggest the virus functionally impacts the hippocampal system as well.

Antiretroviral Therapy in HIV Infection

BACKGROUND

The effect on neuropsychological function of antiretroviral drugs that are able to penetrate into the brain in effective concentration (neuroactive drugs) remains unclear.

OBJECTIVE

To investigate whether highly active antiretroviral therapy (HAART) containing neuroactive drugs is associated with better neuropsychological performance in patients with human immunodeficiency virus disease.

DESIGN

Cross-sectional survey.

SETTING

Tertiary referral hospital outpatient clinics.

PATIENTS

The study population consisted of 97 individuals positive for human immunodeficiency virus (stage C3, 1993 Centers for Disease Control and Prevention classification) whose condition had been stable on their current HAART regimen for a mean +/- SD of 18.5 +/- 16.5 months and who were aged 48.14 +/- 9.38 years. The patient groups were analyzed according to whether their regimen contained 3 or more neuroactive drugs (neuroHAART group; n = 41) or not (HAART group; n = 56). Thirty seronegative men matched for age and education were recruited as controls.

MAIN OUTCOME MEASURE

Neuropsychological performance on 7 cognitive domains.

RESULTS

The neuroHAART and HAART groups did not differ from one another on neuropsychological performance, but both patient groups were impaired compared with controls. Impaired patients in each treatment group were compared, and the neuroHAART group showed significantly better memory performance, unrelated to plasma viral load, than the HAART group.

CONCLUSION

No direct benefit of neuroactive HAART therapy was found in patients with advanced human immunodeficiency virus infection. However, in neuropsychologically impaired patients, there was a benefit in memory function. This suggests that a threshold of neuropsychological impairment is required for the benefit of neuroactive HAART.

Memory Implications of a “Fornix White Line” in HIV Infection

The "fornix white line" (FWL) is a brain abnormality detected on magnetic resonance imaging (MRI) in some people with human immunodeficiency virus (HIV) infection. This finding has previously been associated with clinical findings of cognitive disturbance, particularly regarding memory. The current study provides preliminary substantiation of the previously reported clinical finding of FWL-associated memory disturbance through formal psychometric evaluation over time. Specifically, despite comparable baseline performances, 8-10 months later subjects without the FWL improved performance on neuropsychological verbal memory testing, while subjects with the FWL declined; the magnitude of this dissociation on follow-up was 1.5 to 2.2 standard deviations. In contrast, general cognitive status, as assessed through performance on the Mini-Mental State Exam, remained comparable between groups and stable over time. Further, the comparable CD4 count and Karnofsky scores at baseline counters the argument that the FWL is simply a marker of HIV disease progression. These preliminary findings suggest the need for future research of the hypotheses raised thereby; particularly salient is the hypothesis that the FWL may serve as an earlier marker indicating anti-CMV treatment before memory impairment is clinically apparent.

Cognitive outcome in acute sporadic encephalitis

Acute encephalitis is an inflammation of the brain parenchyma. In the United States, 20,000 cases occur yearly. A variety of cognitive deficits, often the sole cause of disability, may persist after the acute stage. Still, infectious diseases tend to be covered only briefly in neuropsychological handbooks. Recent literature demonstrates the heterogeneity of both amnestic disorders and the outcome following encephalitides. Herpes Simplex virus (HSV), the most common single etiology of sporadic encephalitis, usually causes the most severe symptoms. Modern antiviral medication, however, seems to improve the cognitive outcome. Much less is known about non-HSV encephalitides, where both mild and severe defects have been observed. This article summarizes the current knowledge and also calls upon a more active neuropsychological research in the area.

Neuropsychiatric correlates of memory-metamemory dissociations in HIV-infection

Ninety-one adults with HIV-infection who varied in the concordance between their subjective memory complaints (or metamemory) on the Patient's Assessment of Own Functioning (Chelune, Heaton, & Lehman, 1986) and their memory performance on the California Verbal Learning Test (CVLT), were compared on the Beck Depression Inventory (BDI), and on neuropsychological (NP) tests of attention, language, psychomotor speed, and conceptual problem-solving. Subjects with low memory complaints and normal CVLT performance (n = 29) had low BDI scores and were normal in all other NP abilities. Subjects with high memory complaints and impaired CVLT performance (n = 20) had elevations on the BDI as well as NP impairments in psychomotor speed and category fluency. Subjects with low memory complaints but impaired CVLT performance (n = 16) had low BDI scores and were selectively impaired in conceptual problem-solving. Subjects with high memory complaints but normal CVLT performance (n = 26) had high BDI scores and normal NP functioning in all other abilities. These results suggest that there are at least two key determinants to metamemory inaccuracy in HIV-infection, namely, frontal executive impairments and mood disturbance.

Characterization of learning and memory deficits in C57BL/6 mice infected with LP-BM5, a murine model of AIDS

Mice infected with an immunosuppressive murine leukemia virus mixture, LP-BM5 show a profound immunosuppression described as murine acquired immune deficiency syndrome (AIDS). In the present study, we characterized learning and memory deficits in C57BL/6 mice infected with LP-BM5. Spontaneous alternation behavior in a Y-maze and latent learning (spatial attention) in a water-finding test, as well as spatial reference and reversal learning in a water maze test, were significantly impaired in the mice infected with LP-BM5. These deficits appeared in the absence of any motoric and visual impairment as assessed by open-field, rotarod and visual water maze tests. These results suggest that cognitive functions are impaired in the mice infected with LP-BM5. Furthermore, LP-BM5-infected mice may be useful as a model for the AIDS dementia complex.

Complicated varicella zoster infection in 8 paediatric patients and review of literature

BACKGROUND

This is a study of complicated varicella zoster infection in paediatric patients.

AIM

To find out the number of patients with such complications, the types of complications and their outcome.

METHOD

This involved a retrospective review of the case records of 8 patients who presented to our unit over a 12-month period (Jan-Dec 96). All patients were previously well without any underlying immunodeficiency. Varicella zoster (VZ) infection was confirmed by VZ immunofluorescence from vesicular fluid.

RESULTS

CMS complications accounted for 6 of the 8 cases. Of these, 3 presented with encephalitis, 2 with cerebella ataxia and 1 with aseptic meningitis and cerebella ataxia. Of the non-CNS cases, 1 presented with glomerulonephritis with superimposed staphylococcus infection of skin ulcers; the other had disseminated VZ infection with haemorrhagic vesicles, hepatitis, ileus with mesenteric adenitis and disseminated intravascular coagulation.

OUTCOME

The patient with disseminated VZ infection and multiple organ involvement died 5 days after a stormy course. One patient with encephalitis who had status epilepticus for 2 hours had behavioural problems and poor memory. The remaining 6 patients had no sequelae.

CONCLUSION

VZ infection usually a minor illness, can result in serious life-threatening complications in previously healthy patients.