Preliminary report of a genetic basis for cognitive decline after cardiac operations. The Neurologic Outcome Research Group of the Duke Heart Center

Exploring the combined effects of sleep apnea and APOE-e4 on biomarkers of Alzheimer's disease

Objective

We determined the interactive associations of apolipoprotein e4 (APOE-e4), and obstructive sleep apnea (OSA) on biomarkers of Alzheimer's disease and examined for racial/ethnic differences of this association.

Methods

We used data from the National Alzheimer's Coordinating Center Uniform Dataset (NACC UDS). All participants undergo annual observations, including demographic survey, battery of neuropsychological tests, blood draw (with genotyping), and a clinical evaluation with medical and cognitive/dementia status assessment, while a subset of participants have cerebrospinal fluid (CSF) biomarkers and neuroimaging data. Biomarkers of AD were characterized as the presence of abnormally low amyloid in CSF, via validated Aβ42 cut off protocols, and total segmented hippocampal volume, and volume of white matter hyper intensities (WMH). While clinical markers (to preview cognitive relationships) were characterized via the Montreal Cognitive Assessment (MOCA).

Results

Biomarker and clinical marker data were derived from 1,387 participants at baseline (mean age = 69.73 ± 8.32; 58.6% female; 13.7% Black/African American), 18.4% of the sample had sleep apnea, and 37.9% were APOE-e4 carriers. Our results confirmed previous reports that OSA and APOE-e4 were independently associated with AD through abnormal levels of amyloid (F (1,306) = 4.27; p = 0.040; F (1,285) = 60.88; p < 0.000, respectively), WMH volume (F (1,306) = 4.27; p = 0.040; F (1,285) = 60.88; p < 0.000, respectively), and MOCA scores (F (1,306) = 4.27; p = 0.040; F (1,285) = 60.88; p < 0.000, respectively). No significant interaction between OSA and APOE-e4 relative to amyloid emerged, however, race stratified analyses indicated the interaction of OSA and APOE-e4 and was significantly associated with WMH and hippocampal volume in Black/African American, but not white participants.

Conclusion

OSA and APOE-e4 are interactively associated with WHM in Black/African Americans. This interaction may partially explicate increased levels of risk in this population.

ABCA7 rs3764650 Polymorphism is Associated with Delayed Neurocognitive Recovery

Background

Several studies have shown that ATP-binding cassette transporter A7 (ABCA7) gene variation is associated with cognitive impairment. This study was aimed to investigate the relationship between ABCA7 rs3764650 polymorphism and perioperative neurocognitive disorder (pNCD).

Methods

A total of 132 elderly patients aged 65 and over who underwent elective non-cardiac surgery were enrolled in the study, while 28 healthy volunteers matching age and sex were recruited as the control group. A battery of neuropsychological tests was conducted 1 day before, 7 days, and 3 months after surgeries. Delayed neurocognitive recovery (dNCR) and postoperative mild or major neurocognitive disorder (POCD) were determined using the Z value method. The venous blood sample of the surgical patients was taken before the operation. Genotyping of rs3764650 was performed using polymerase chain reaction amplification and restriction fragment length polymorphism analysis.

Results

The incidences of dNCR and POCD were 29.7% and 16.8% at 7 days and 3 months after surgery, respectively. The G allele frequency and GG frequency of dNCR patients were significantly higher than that of non-dNCR patients (43.3% vs 28.2%, P=0.035; 23.3% vs 4.2%, P=0.013, respectively) at 7 days following surgery. No significant differences in ABCA7 alleles between POCD and non-POCD patients were observed 3 months postoperatively.

Conclusion

ABCA7 rs3764650 gene polymorphism is associated with dNCR and GG genotype might be a predisposing factor for postoperative cognitive impairment in Chinese Han elderly populations.

The New Frontier of Perioperative Cognitive Medicine for Alzheimer's Disease and Related Dementias

This is a review of preoperative cognitive assessment and other healthcare gaps in the care of older adults at risk for Alzheimer's disease and related dementias (ADRD) who have elected surgery with anesthesia. It summarizes concerns regarding ADRD perioperative healthcare, perioperative cognitive, and neuronal domains of vulnerability. It also offers a plan for phased preoperative cognitive screening and perioperative cognitive intervention opportunities. An argument is made for why medical professionals in the perioperative setting need fundamental training in cognitive-behavioral principles, an understanding of neurodegenerative diseases of aging, and an appreciation of the immediate and long-term medical risks for such patients undergoing anesthesia. The author's goal is to encourage readers to consider perioperative cognitive medicine as a new frontier for generating evidence-based care approaches for at-risk older adults with neurodegenerative disorders who require procedures with anesthesia.

Volatile and Intravenous Anesthetics for Brain Protection in Cardiac Surgery: Does the Choice of Anesthesia Matter?

Postoperative neurologic complications have a significant effect on morbidity, mortality, and long-term disability in patients undergoing cardiac surgery. The etiology of brain injury in patients undergoing cardiac surgery is multifactorial and remains unclear. There are several perioperative causative factors for neurologic complications, including microembolization, hypoperfusion, and systemic inflammatory response syndrome. Despite technologic advances and the development of new anesthetic drugs, there remains a high rate of postoperative neurologic complications. Moreover, despite the strong evidence that volatile anesthesia exerts cardioprotective effects in patients undergoing cardiac surgery, the neuroprotective effects of volatile agents remain unclear. Several studies have reported an association of using volatile anesthetics with improvement of biochemical markers of brain injury and postoperative neurocognitive function. However, there is a need for additional studies to define the optimal anesthetic drug for protecting the brain in patients undergoing cardiac surgery.

Association between BDNF rs6265 polymorphisms and postoperative cognitive dysfunction in Chinese Han Population

INTRODUCTION

Brain-derived neurotrophic factor (BDNF) plays a critical role in the pathogenesis of postoperative cognitive dysfunction (POCD). In present study, we aimed to assess the possible association between POCD and BDNF rs6265 polymorphisms.

METHODS

124 patients aged 60 years or older scheduled for elective surgery under general anesthesia and 25 age- and gender-matched healthy volunteers were recruited. POCD was identified using a neuropsychological test battery administered preoperatively, 7 days, and 3 months after surgery. Genotyping of rs6265 was performed using polymerase chain reaction amplification and restriction fragment length polymorphism analysis.

RESULTS

99 patients and 25 healthy controls were finally enrolled in the analysis. 29(29.3%) and 18(18.2%) of 99 patients had POCD at 7 days and 3 months after surgery, respectively. The patients carrying a G allele at the rs6265 locus showed a lower risk for POCD than an A allele carriers on postoperative 7 days, but not 3 months after surgery (OR = 0.67; 95% CI: 0.47-0.96; p = .017; OR = 0.69; 95% CI: 0.42-1.13; p = .14, respectively). The risk of POCD at 7 days following surgery was significantly lower in additive model (OR = 0.41; 95% CI: 0.2-0.84; p = .015) and dominant model (OR = 0.35; 95% CI: 0.13-0.96; p = .042).

CONCLUSION

We tentatively demonstrate that BDNF rs6265 polymorphisms might be associated with occurrence of POCD at 7 days after surgery and the A > G mutant at the rs6265 locus be likely a protective factor for early POCD in Chinese Han population.

Strategies to Protect the Brain During Cardiac Surgery

Despite significant advances in cardiopulmonary by pass (CPB) technology, surgical techniques, and anes thetic management, central nervous system (CNS) com plications remain a common and costly problem after CPB. Stroke is often considered a rare and unprevent able complication of cardiac surgery. Recent studies have shown that through the use of echocardiography and historical risk stratification strategies, we can de fine which patients are at substantially greater risk for CNS injury. Through enhanced understanding of the etiology of stroke and perioperative factors, which are associated with potential for neuroprotection or injury extension, there now exists a greater potential than ever to substantially reduce neurological injury associ ated with cardiac surgery. Strategies and theories of stratifying patients at risk and secondarily reducing that risk are described, as well as consideration for early postoperative assessment to allow treatment when events occur.

Deep Hypothermia and Circulatory Arrest in Adults

Brain protection during cardiopulmonary bypass has been the subject of intense research. Deep hypothermic circulatory arrest (DHCA) continues to be used for that goal during complex aortic arch and large intracranial aneurysm surgeries. The anesthetic management for adult patients undergoing these types of procedures requires specific knowledge and expertise. Based on our experience and review of the current literature, the authors highlight the key areas of the anesthetic plan, discussing the risk factors associated with adverse neurologic outcome as well as the rationale for decisions regarding specific monitors and medications. In the conclusion an anesthetic protocol for adult patients undergoing DHCA is suggested.

Cognitive Dysfunction After Cardiac Surgery: Revisiting Etiology

Cognitive dysfunction remains a frequent complication of cardiac surgery. Despite many years of research, few preventive strategies and no definitive therapeutic options exist for the management of this troublesome clinical problem. This shortcoming may be secondary to an incomplete understanding of the pathophysiology and etiology of cognitive loss after cardiac surgery; a better understanding of the etiology is essential to finding new therapies. The etiology of cognitive dysfunction after cardiac surgery is multifactorial and includes cerebral microembolization, global cerebral hypoperfusion, systemic and cerebral inflammation, cerebral temperature perturbations, cerebral edema, and possible blood-brain barrier dysfunction, all superimposed on genetic differences in patients that may make them more susceptible to injury or unable to repair from injury once it has occurred. This review expands on these potential etiologies in detailing the evidence for their existence.

Genetic Influences on Cerebral Outcome After Cardiac Surgery

Just as the influence of genetic variation on patient outcomes is being discussed in many other areas of medicine, so too are its effects on cerebral outcome after cardiac surgery now being described. Whereas early studies focused on neurocognitive outcome, where the single nucleotide polymorphisms of APOE4 and PLA2 were the first investigated genetic targets, stroke is now being elaborated on with related single and multi-gene single nucleotide polymorphisms having been identified. Our work has established key links between post-cardiac surgery stroke and C-reactive protein (3’UTR 1846C/T) and interleukin-6 (-174 G/C) single nucleotide polymorphisms.

Genetic Predictors of Perioperative Neurologic and Neuropsychological Injury and Recovery

Central nervous system (CNS) dysfunction after cardio pulmonary bypass represents a continuum from coma and focal stroke to cognitive deficits after surgery. Despite the marked increase in investigation of neuro logic and neurocognitive deficits after cardiac surgery, causative factors fail to predict the majority of the variance in the observed incidence of both early and late neurocognitive decline pointing to some inherent indi vidual susceptibility to injury. The authors' investigative team recently discovered a genetic association be tween late-onset Alzheimer's disease and the apolipo protein E (APOE, gene; apoE, protein) ∈-4 gene. This finding triggered many recent studies that have shown an important role of apoE in the determination of neurologic injury and recovery following a variety of acute ischemic insults including intracerebral hemor rhage, closed-head injury, as well as acute stroke and dementia pugilistica. Most important to the current discussion is the authors' recent report documenting preliminary evidence of an association of APOE4 with neurocognitive decline after cardiac surgery. This re view discusses the authors' hypothesis that the bio chemical products coded by this gene are not available to protect and repair the neurons of the CNS during cardiac surgery resulting in deficits of memory, atten tion, and concentration. Potential mechanisms of apoE's association with acute neurologic injury are discussed including regulation of the inflammatory response. The authors have recently determined that apoE, in vivo, modulates the release of nitric oxide and tumor necro sis factor a. This may compound the autonomic dysreg ulation recently reported in the aging population. The authors' preliminary data associating APOE4 with cogni tive impairment after cardiac surgery support this hy pothesis. The different potential mechanisms of apoE function in neuronal injury and recovery are not mutu ally exclusive, and it is likely that apoE modulates the CNS injury response at several functional levels.

Organizational topology of brain and its relationship to ADHD in adolescents with d-transposition of the great arteries

OBJECTIVE

Little is currently known about the impact of congenital heart disease (CHD) on the organization of large-scale brain networks in relation to neurobehavioral outcome. We investigated whether CHD might impact ADHD symptoms via changes in brain structural network topology in a cohort of adolescents with d-transposition of the great arteries (d-TGA) repaired with the arterial switch operation in early infancy and referent subjects. We also explored whether these effects might be modified by apolipoprotein E (APOE) genotype, as the APOE ε2 allele has been associated with worse neurodevelopmental outcomes after repair of d-TGA in infancy.

METHODS

We applied graph analysis techniques to diffusion tensor imaging (DTI) data obtained from 47 d-TGA adolescents and 29 healthy referents to construct measures of structural topology at the global and regional levels. We developed statistical mediation models revealing the respective contributions of d-TGA, APOE genotype, and structural network topology on ADHD outcome as measured by the Connors ADHD/DSM-IV Scales (CADS).

RESULTS

Changes in overall network connectivity, integration, and segregation mediated worse ADHD outcomes in d-TGA patients compared to healthy referents; these changes were predominantly in the left and right intrahemispheric regional subnetworks. Exploratory analysis revealed that network topology also mediated detrimental effects of the APOE ε4 allele but improved neurobehavioral outcomes for the APOE ε2 allele.

CONCLUSION

Our results suggest that disruption of organization of large-scale networks may contribute to neurobehavioral dysfunction in adolescents with CHD and that this effect may interact with APOE genotype.

Is the APOE ∊4 Allele a Risk to Person-Environment Fit?

This study uses Lawton’s model of “the good life” to examine whether the Apolipoprote in E-∊4 genotype functions as a risk factor not only for specific diseases but also for a misfit between elders’ personal needs and their physical and social environments. A biracial cohort of communitydwelling elders from five North Carolina Piedmont counties was assessed annually for 10 years. Six-year survivors (N = 2,076) were genotyped for this retrospective-prospective cohort study. Compared to those in whom this allele was absent, participants with the 4 allele were not different in social or residential resources, social behavioral competence, or perceived quality of resources. Exposed elders had an excess 10-year adjusted risk of institutionalization of 1.72 (95% CI = 1.29, 2.29), totally mediated by cognitive problems. The threat of the APOE 4 genotype to person-environment fit is mediated by cognitive problems, a finding that has focused but important implications for residential decision making in late life.

Apolipoprotein epsilon 4 genotype is associated with less improvement in cognitive function five years after cardiac surgery: a retrospective cohort study

PURPOSE

Cognitive performance after cardiac surgery can be impaired, and genetic risk factors have previously been suggested. When compared with other isoforms of the gene, the apolipoprotein epsilon 4 (APOE4) allele is associated with worse outcomes in many neurologic disorders. We hypothesized that the APOE4 allele is associated with less favourable cognitive function five years after surgery.

METHODS

Caucasian patients enrolled in previously reported prospective cognitive trials in both cardiac and non-cardiac surgery participated in this retrospective cohort study. Neuropsychological function was assessed at baseline and five years postoperatively. The relationship between change in cognitive index score and APOE was evaluated using multivariable linear regression. An additive genetic model toward the epsilon 4 allele was applied with adjustment for baseline cognition, years of education, age, presence of diabetes in both cohorts, and presence of coronary artery disease in the non-cardiac surgery cohort.

RESULTS

A total of 357 patients were included in this study. In the cardiac surgery group (n = 233), baseline cognitive index (P < 0.001), years of education (P = 0.04), age at time of surgery (P < 0.001), and the APOE4 allele (P = 0.009), were associated with a five-year change in cognitive index. Patients carrying the APOE4 allele showed less improvement in cognitive index scores five years after cardiac surgery compared with patients without the APOE4 allele. In the non-cardiac surgery (n = 124) group, no association was found between APOE4 allele status and change in cognitive index.

CONCLUSION

We report an association between APOE4 and neurocognitive function five years following cardiac surgery. Preoperative identification of patients with the APOE4 genotype may improve stratification of cardiac surgery patients at risk for a less favourable cognitive trajectory.

Apolipoprotein E genotype and outcome in infants with hypoxic-ischemic encephalopathy

BACKGROUND

Adults with the apolipoprotein E (APOE) gene alleles e4 and e2 are at high risk of poor neurological outcome after brain injury. The e4 allele has been associated with cerebral palsy (CP), and the e2 allele has been associated with worse neurological outcome with congenital heart disease. This study was done to test the hypothesis that the APOE genotype is associated with outcome among neonates who survive after hypoxic-ischemic encephalopathy (HIE).

METHODS

We conducted a cohort study of infants who survived HIE and had 18-22 mo standardized neurodevelopmental evaluations to assess associations between disability and the APOE genotypes e3/e3, e4/-, and e2/-.

RESULTS

A total of 139 survivors were genotyped. Of these, 86 (62%) were of the e3/e3, 41 (29%) were of the e4/-, and 14 (10%) were of the e2/- genotypes. One hundred and twenty-nine infants had genotype and follow-up data; 26% had moderate or severe disabilities. Disability prevalence was 30 and 19% among those with and without the e3/e3 genotype, 25 and 26% among those with and without the e2 allele, and 18 and 29% among those with and without the e4 allele, respectively. None of the differences were statistically significant. CP prevalence was also similar among genotype groups.

CONCLUSION

Disability was not associated with the APOE genotype in this cohort of HIE survivors.

Hereditary vulnerabilities to post-operative cognitive dysfunction and dementia

In view of multiple prospective investigations reporting an incidence of 10% or greater in elderly patients after cardiac and non-cardiac procedures, it is surprising that no families, twins or even individual cases have been reported with persistent post-operative cognitive dysfunction (POCD) or post-operative dementia (POD) that is otherwise unexplained. As POCD and POD research has shifted in recent years from surgical and anesthetic variables to predictors of intrinsic, patient-specific susceptibility, a number of markers based on DNA sequence variation have been investigated. Nevertheless, no heritable, genomic indices of persistent POCD or post-operative dementia lasting 3 months or longer after surgery have been identified to date. The present manuscript surveys challenges confronting the search for markers of heritable vulnerability to POCD and POD, and proposes steps forward to be taken now, including the addition of surgical and anesthetic descriptors to ongoing longitudinal dementia protocols and randomized clinical trials (RCTs) comprising serial psychometric testing, and a fresh focus on phenotypes and genotypes shared between outliers with "extreme" POCD and POD traits.

Effect of piracetam on the cognitive performance of patients undergoing coronary bypass surgery: A meta-analysis

Cognitive impairments are observed in numerous patients following coronary bypass surgery, and piracetam are nootropic compounds that modulate cerebral functions by directly enhancing cognitive processes. The present meta-analysis was conducted to evaluate the protective effect of piracetam on the cognitive performance of patients undergoing coronary bypass surgery. The relevant studies were identified by searching Medline, EMBASE, PubMed and the Cochrane Library up to June 2013 and the pertinent bibliographies from the retrieved studies were reviewed. Data were selected from the studies according to predefined criteria. The meta-analysis included two randomized control trials involving 184 patients and including the Syndrom-Kurz test (SKT). Findings of the meta-analysis showed that following treatment the change from baseline observed in five SKT subtest scores, conducted with piracetam patients, indicated a significant advantage over those patients that were in the placebo group. The subtests included immediate pictured object recall, weighted mean difference (WMD)=0.91, 95% confidence interval (CI) 0.51–1.31, P<0.00001; delayed pictured object recall, WMD=0.74, 95% CI 0.19–1.28, P=0.008; delayed picture recognition, WMD=0.82, 95% CI 0.31–1.31, P=0.001; immediate word recall, WMD=0.87, 95% CI 0.47–1.28, P<0.0001; and letter interference, WMD=3.46, 95% CI −5.69 to −1.23, P=0.002. These results indicated that piracetam may have been effective in improving the short-term cognitive performance of patients undergoing coronary bypass surgery. High quality, well-controlled and longer randomized trials are required to corroborate this result.

Association between APOE epsilon 4 allele and postoperative cognitive dysfunction: a meta-analysis

BACKGROUND

Carriers of the apolipoprotein E epsilon 4 allele (APOEε4) may be at increased risk of postoperative cognitive dysfunction (POCD), but this association has not been reported consistently. We conducted a meta-analysis to derive a more precise conclusion.

METHODS

The PubMed, EBSCO and EMBASE databases were searched for eligible studies published in English before March 2013. The association between APOEε4 and POCD was expressed by the odds ratio (OR) with 95% confidence interval (CI). Funnel plots were constructed and publication bias assessed by Egger's test.

RESULTS

Nine studies encompassing 1063 APOEε4 carriers and 2983 noncarriers were included. At about 1-week postsurgery, a significant association between APOEε4 and POCD was found (OR 1.83, 95% CI: 1.18-2.85), but the association was no longer significant after removing one large study (OR 1.35, 95% CI: 0.92-1.97). Stratified analysis of cardiac/vascular surgery patients also yielded no significant correlation (OR 1.62, 95% CI: 0.80-3.28). One to three months postsurgery, neither the overall analysis (OR 1.56, 95% CI: 0.87-2.81) nor the stratified analysis of cardiac/vascular surgery patients (OR 3.33, 95% CI: 0.55-20.22) indicated a significant correlation. APOEε4 was also not correlated with POCD at 1-year postsurgery (OR 1.15, 95% CI: 0.71-1.86). No evidence of publication bias was revealed by Egger's test.

CONCLUSIONS

The APOEε4 allele was associated with a significantly increased POCD risk about 1-week postsurgery, but the association depended on one large study. No association was found 1-3 months and 1-year postsurgery.

Cognitive dysfunction after cardiac surgery: Pathophysiological mechanisms and preventive strategies

Despite improvements in surgical techniques and the implementation of effective brain protection strategies, the incidence of brain injury after cardiac surgery has remained relatively constant over the years as patients have become older and sicker. Cognitive dysfunction is the most common clinical manifestation of brain injury after cardiac surgery. Its occurrence is related to a combination of three factors that are often associated with cardiopulmonary bypass (CPB): embolism, hypoperfusion, and the inflammatory response. However, such factors and their potential cerebral consequences are not exclusive to CPB. Postoperative cognitive dysfunction also afflicts patients who undergo cardiac surgery without CPB as well as nonsurgery patients who undergo transcatheter interventions. There is growing evidence that patient-related factors such as the presence of (cerebro)vascular risk factors play an important role in both early and late postoperative cognitive dysfunction.

Open-heart surgery increases cerebrospinal fluid levels of Alzheimer-associated amyloid β

BACKGROUND

Neurocognitive dysfunction occurs frequently after open-heart surgery. It has been suggested that cognitive decline after cardiac surgery with cardiopulmonary bypass (CPB) could be a functional consequence of Alzheimer's disease (AD)-like neuropathological changes. The aim of the present study was to evaluate the cerebrospinal fluid (CSF) levels of amyloid β peptide (Aβ(1-42) ) and soluble fragments of amyloid precursor protein (sAPP) as well as the cerebral inflammatory response to open-heart surgery.

METHODS

Ten patients undergoing aortic valve replacement with CPB were included. CSF was obtained the day before and 24 h after surgery for assessment of CSF levels of Aβ(1-42) α-cleaved sAPP and β-cleaved sAPP (sAPP-β). Furthermore, CSF and serum levels of the inflammatory cytokines: tumour necrosis factor alpha (TNF-α), interleukin-6 (IL-6) and interleukin-8 (IL-8) were also assessed.

RESULTS

Cardiac surgery with CPB increased CSF levels of Aβ(1-42) from 447 ± 92 to 641 ± 83 ng/l (P = 0.011), while CSF levels of sAPP-β decreased from 276 ± 35 to 192 ± 21 ng/ml (P = 0.031). CSF levels of TNF-α increased from ≤ 0.60 to 0.79 ± 0.26 ng/l (P = 0.043), IL-6 from 1.89 ± 0.53 to 22.8 ± 6.9 ng/l (P = 0.003) and IL-8 from 39.8 ± 7.8 to 139 ± 18.3 ng/l (P < 0.001).

CONCLUSIONS

Cardiac surgery with CPB causes a profound cerebral inflammatory response, which was accompanied by increased post-operative CSF levels of the AD biomarker Aβ(1-42) . We hypothesize that these changes may be relevant to Alzheimer-associated amyloid build-up in the brain and cognitive dysfunction after cardiac surgery with CPB.

Results of genome-wide analyses on neurodevelopmental phenotypes at four-year follow-up following cardiac surgery in infancy

BACKGROUND

Adverse neurodevelopmental sequelae are reported among children who undergo early cardiac surgery to repair congenital heart defects (CHD). APOE genotype has previously been determined to contribute to the prediction of these outcomes. Understanding further genetic causes for the development of poor neurobehavioral outcomes should enhance patient risk stratification and improve both prevention and treatment strategies.

METHODS

We performed a prospective observational study of children who underwent cardiac surgery before six months of age; this included a neurodevelopmental evaluation between their fourth and fifth birthdays. Attention and behavioral skills were assessed through parental report utilizing the Attention Deficit-Hyperactivity Disorder-IV scale preschool edition (ADHD-IV), and Child Behavior Checklist (CBCL/1.5-5), respectively. Of the seven investigated, three neurodevelopmental phenotypes met genomic quality control criteria. Linear regression was performed to determine the effect of genome-wide genetic variation on these three neurodevelopmental measures in 316 subjects.

RESULTS

This genome-wide association study identified single nucleotide polymorphisms (SNPs) associated with three neurobehavioral phenotypes in the postoperative children ADHD-IV Impulsivity/Hyperactivity, CBCL/1.5-5 PDPs, and CBCL/1.5-5 Total Problems. The most predictive SNPs for each phenotype were: a LGALS8 intronic SNP, rs4659682, associated with ADHD-IV Impulsivity (P=1.03 × 10(-6)); a PCSK5 intronic SNP, rs2261722, associated with CBCL/1.5-5 PDPs (P=1.11 × 10(-6)); and an intergenic SNP, rs11617488, 50 kb from FGF9, associated with CBCL/1.5-5 Total Problems (P=3.47 × 10(-7)). 10 SNPs (3 for ADHD-IV Impulsivity, 5 for CBCL/1.5-5 PDPs, and 2 for CBCL/1.5-5 Total Problems) had p<10(-5).

CONCLUSIONS

No SNPs met genome-wide significance for our three neurobehavioral phenotypes; however, 10 SNPs reached a threshold for suggestive significance (p<10(-5)). Given the unique nature of this cohort, larger studies and/or replication are not possible. Studies to further investigate the mechanisms through which these newly identified genes may influence neurodevelopment dysfunction are warranted.

APOE gene polymorphisms and diabetic peripheral neuropathy

Genetic factors may influence the natural course of diabetic peripheral neuropathy and explain some of its variability. The aim of this review was to examine the association between apolipoprotein E (apoE) gene polymorphisms and diabetic peripheral neuropathy. Four relevant studies were identified. The two earlier works provided evidence that the ɛ4 allele is a risk factor for this complication, while the two more recent studies were negative. Important differences in the methodology used and in the populations included are obvious, rendering difficult the comparison between studies. In conclusion, the association between APOE gene polymorphisms and diabetic peripheral neuropathy is still unclear. Available evidence is rather limited and results have so far been contradictory. Future studies should employ more robust methodology, adjusting for potential confounders and for the prevalence of neuropathy in the general population with diabetes.

Ondasetron versus haloperidol for the treatment of postcardiotomy delirium: a prospective, randomized, double-blinded study

Background

To investigate the controlling efficacy of ondasetron and haloperidol in regard to the postcardiotomy delirium.

Methods

We included in this prospective, randomized, double-blinded study 80 patients who developed delirium after heart surgery with the application of heart lung-machine. The patients were divided into two, equally-sized groups, which on detection of delirium received ondasetron 8 mg iv or haloperidol 5 mg iv respectively. The statistical analysis compared the baseline and demographic characteristics of the two groups (age, gender, comorbidities, years of education, type of surgery etc.).

Results

Both ondasetron and haloperidol had very good delirium controlling effects, without statistically significant differences.

Discussion-Conclusions

Ondasetron and haloperidol are efficient agents as far as the treatment of postcardiotomy delirium is concerned. As, in addition, ondasetron bares milder side-effects, we believe this could be the agent of choice in patients developing postcardiotomy delirium in the future.

Can postoperative cognitive dysfunction be avoided?

Postoperative cognitive dysfunction (POCD) refers to a postoperative decline in cognitive function compared with preoperative cognitive function. Diagnosis requires pre- and postoperative testing, the latter of which is usually performed both 7 days and 3 months postoperatively. Although several risk factors for POCD have been described, age is the only consistently reported risk factor. Postoperative cognitive dysfunction is often transient. It may last several months, and is associated with leaving the labor market prematurely and increased mortality. As the pathophysiology of POCD is still a matter of debate and is likely to be multifactorial, there are no widely accepted prophylactic and therapeutic interventions. In this article, we discuss POCD's definition, risk factors, long-term significance, and pathophysiology. We also present data on prophylactic interventions that have been investigated in clinical trials.

Neurocognitive correlates of nocturnal oxygen desaturation in a memory clinic population

Previous studies suggested that sleep apnea is associated with neurocognitive impairments but did not examine populations most likely to have clinically relevant impairments. Cross-sectional, retrospective analyses were performed on 108 patients (65 with mild cognitive impairment, 43 with dementia) seen in an academic medical center. Results indicated that severity of oxygen desaturation was associated with cognitive impairments in attention and executive function domains, even after controlling for age, sex, education, and depressive symptoms. Strength of associations was influenced by cardiovascular disease. Screening for nocturnal oxygen desaturation may be a useful procedure to assess for a potentially reversible cause of cognitive impairment.

Neurological biomarkers in the perioperative period

The rapid detection and evaluation of patients presenting with perioperative neurological dysfunction is of great clinical relevance. Biomarkers have been defined as biological molecules that can be used as an indicator of new onset or progression of a biological process or effect of treatment. Biomarkers have become increasingly important in this setting to supplement other modalities of diagnosis such as EEG, sensory- or motor-evoked potential, transcranial Doppler, near-infrared spectroscopy, or imaging methods. A number of neuro-proteins have been identified and are currently under investigation for potential to provide insights into injury severity, outcome, and the ability to monitor cellular damage and molecular events that occur during neurological injury. S100B is a protein released by glial cells and is considered a marker of blood-brain barrier dysfunction. Clinical studies in patients undergoing cardiac and non-cardiac surgery indicate that serum levels of S100B are increased intraoperatively and after operation. The neurone-specific enolase has also been extensively investigated as a potential marker of neuronal injury in the context of cardiac and non-cardiac surgery. A third biomarker of interest is the Tau protein, which has been linked to neurodegenerative disorders. Tau appears to be more specific than the previous two biomarkers since it is only found in the central nervous system. The metalloproteinase and ubiquitin C terminal hydroxylase-L1 (UCH-L1) are the most recently researched markers; however, their usefulness is still unclear. This review presents a comprehensive overview of S100B, neuronal-specific enolase, metalloproteinases, and UCH-L1 in the perioperative period.

APOE ε 4 allele and CSF APOE on cognition in HIV-infected subjects

The significance of the cerebrospinal fluid (CSF) Apolipoprotein E (APOE) level and whether it might have differential effects on brain function due to the presence of APOE ε 4 allele(s) in HIV-infected patients are unknown. However, APOE ε 4 allele has been associated with greater incidence of HIV-associated dementia and accelerated progression of HIV infection. Here, we show further evidence for the role of APOE ε 4 in promoting cognitive impairment. We measured the APOE levels in the CSF of HIV-infected individuals. HIV+ subjects showed lower CSF APOE proteins than SN controls (-19%, p= 0.03). While SN subjects with or without ε 4 allele showed no difference in CSF APOE levels, ε 4+ HIV+ subjects had similar levels to the SN subjects but higher levels than ε 4- HIV+ subjects (+34%, p= 0.01). Furthermore, while HIV+ subjects with ε 2 or ε 3 allele(s) showed a positive relationship between their CSF APOE levels and cognitive performance on the speed of processing domain (r= +0.35, p= 0.05), ε 4+ HIV+ subjects, in contrast, exhibited a negative relationship such that those with higher levels of CSF APOE(4) performed worse on the HIV Dementia Scale (r= -0.61, p= 0.02), had lower Global Cognitive Scores (r= -0.57, p= 0.03), and had poorer performance on tests involving learning (ε 4 allele x [APOE] interaction, p = 0.01). Our findings also suggest that the relatively higher levels of CSF APOE in ε 4+ HIV+ (having primarily APOE4 isoforms) may negatively impact the brain and lead to poorer cognitive outcomes, while those individuals without the ε 4 allele (with primarily APOE2 or APOE3 isoforms) may show compensatory responses that lead to better cognitive performance.

Central neurotoxicity in cancer chemotherapy: pharmacogenetic insights

Central neurotoxicity of chemotherapy is likely to be multifactorial. There are two hypotheses regarding endogenous mechanisms that may be involved, namely the target and the blood-brain barrier transporter hypotheses. Here, we will review candidate genetic determinants for the risk of chemotherapy-induced neurotoxicity, such as polymorphisms involved in the target mechanism. These include polymorphisms in folate metabolizing enzymes and apolipoprotein E, as well as those in blood-brain barrier transporter genes. Currently, the exact role of pharmacogenetics in mechanisms that lead to central neurotoxicity of chemotherapy has not been fully unraveled. Larger, prospective, longitudinal and more uniform studies are needed, with prechemotherapy and follow-up measurements of neuropsychological performance, MRI, PET, genetic profiles and biomarkers relevant for the proposed target and transporter mechanisms.

Mitochondrial dysfunction and Alzheimer's disease

To date, one of the most discussed hypotheses for Alzheimer's disease (AD) etiology implicates mitochondrial dysfunction and oxidative stress as one of the primary events in the course of AD. In this review we focus on the role of mitochondria and mitochondrial DNA (mtDNA) variation in AD and discuss the rationale for the involvement of mitochondrial abnormalities in AD pathology. We summarize the current data regarding the proteins involved in mitochondrial function and pathology observed in AD, and discuss the role of somatic mutations and mitochondrial haplogroups in AD development.

Long-term post-operative cognitive decline in the elderly: the effects of anesthesia type, apolipoprotein E genotype, and clinical antecedents

Cognitive dysfunction in the elderly commonly observed following anesthesia has been attributed to age-related neuronal changes exacerbated by pharmacotoxic effects. However, the extent to which these changes may persist following recovery from surgery is still largely unknown. This study investigates the long-term effects of anesthesia on cognitive functioning after orthopedic surgery in 270 elderly patients over the age of 65 who completed a computerized cognitive battery before and 8 days, 4 and 13 months after surgery. Their performance was compared to those of 310 elderly controls who completed the same neuropsychiatric evaluation at baseline and one-year interval. Multivariate analyses adjusted for socio-demographic variables, depressive symptomatology, vascular pathology as well as baseline cognitive performance. We found early and transient post-operative decline in reaction time and constructional praxis. With regard to long-term changes we observed improvement compared to controls in most verbal tasks (probably due to learning effects). On the other hand, a clear dissociation effect was observed for several areas of visuospatial functioning which persisted up to the 13-month follow-up. This specific pattern of visuospatial deficit was found to be independent of apolipoprotein E genotype and closely resembles what has recently been termed vascular mild cognitive impairment, in turn associated with subtle sub-cortical vascular changes. The observation of only minor differences between persons operated by general and regional anesthesia makes it difficult to attribute these changes directly to the anesthetic agents themselves, suggesting that cognitive dysfunction may be attributable at least in part to peri-operative conditions, notably stress and glucocorticoid exposure.

Neurocognitive dysfunction following cardiac surgery

Postoperative neurocognitive decline (POCD) is the most frequently reported form of brain injury in the cardiac surgery setting. Even though most patients recover over a period of several months, recovery is variable and often transient, and early decline may be a marker of neurocognitive dysfunction after several years. Recent studies, however, suggest that late neurocognitive decline after coronary artery bypass graft surgery may not be specific to the use of cardiopulmonary bypass. Large prospective, longitudinal trials with appropriate controls remain necessary to identify how patient characteristics, disease progression, and surgical and anesthetic technique contribute to aging-related neurocognitive decline. This article reviews the current literature on the etiology of POCD following cardiac surgery, discusses strategies to reduce patient risk, and provides some insight into some controversies that merit continued investigation.

Cognitive function after major noncardiac surgery, apolipoprotein E4 genotype, and biomarkers of brain injury

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a significant cause of morbidity after noncardiac surgery. Identified risk factors are largely limited to demographic characteristics. We hypothesized that POCD was associated with apolipoprotein E4 (APOE4) genotype and plasma biomarkers of brain injury and inflammation.

METHODS

Three hundred ninety-four patients older than 55 yr undergoing major elective noncardiac surgery were enrolled in this prospective observational study. Apolipoprotein E genotyping was performed at baseline. Plasma was collected at baseline and end of surgery and at 4.5, 24, and 48-h postoperatively. Six protein biomarkers were assayed (B-type natriuretic peptide, C-reactive protein, D-dimer, matrix metalloproteinase-9, neuron-specific enolase, and S-100B). Neurocognitive testing was conducted at baseline and at 6 weeks and 1 yr after surgery; scores were subjected to factor analysis. The association of APOE4 and biomarkers with POCD was tested using multivariable regression modeling.

RESULTS

Three hundred fifty patients (89%) completed 6-week neurocognitive testing. POCD occurred in 54.3% of participants at 6 weeks and 46.1% at 1 yr. There was no difference in POCD between patients with or without the APOE4 allele (56.6 vs. 52.6%; P = 0.58). The continuous cognitive change score (mean +/- SD) was similar between groups (APOE4: 0.05 +/- 0.27 vs. non-APOE4: 0.07 +/- 0.28; P = 0.53). Two hundred ninety-one subjects (74%) completed testing at 1 yr. POCD occurred in 45.9% of APOE4 subjects versus 46.3% of non-APOE4 subjects (P = 0.95). The cognitive score was again similar (APOE4: 0.08 +/- 0.27 vs. non-APOE4: 0.05 +/- 0.25; P = 0.39). Biomarker levels were not associated with APOE4 genotype or cognition at 6 weeks or 1 yr.

CONCLUSION

Cognitive decline after major noncardiac surgery is not associated with APOE4 genotype or plasma biomarker levels.

Novel mechanisms of central nervous system damage in HIV infection

Human immunodeficiency virus-1 infection of the central nervous system is an early event after primary infection, resulting in motor and cognitive defects in a significant number of individuals despite successful antiretroviral therapy. The pathology of the infected brain is characterized by enhanced leukocyte infiltration, microglial activation and nodules, aberrant expression of inflammatory factors, neuronal dysregulation and loss, and blood–brain barrier disruption. Months to years following the primary infection, these central nervous system insults result in a spectrum of motor and cognitive dysfunction, ranging from mild impairment to frank dementia. The mechanisms that mediate impairment are still not fully defined. In this review we discuss the cellular and molecular mechanisms that facilitate impairment and new data that implicate intercellular communication systems, gap junctions and tunneling nanotubes, as mediators of human immunodeficiency virus-1 toxicity and infection within the central nervous system. These data suggest potential targets for novel therapeutics.

Observation of the density and size of cells in hippocampus and vascular lesion in thalamus of GFAP-apoE transgenic mice

OBJECTIVE

Apolipoprotein E (apoE) is associated with increased risk of age-related diseases, such as Alzheimer's disease (AD) and cerebrovascular disease (CVD). The present study aims to investigate the age-related general morphological changes of the brain in GFAP-apoE transgenic mice, especially the alterations in number and size of hippocampal pyramidal cells and the microvascular lesions in the thalamus.

METHODS

Nine female apoE4/4 mice were divided into 3 groups (n=3 in each group): 3-4 months (young group), 9-10 months (middle-aged group) and 20-21 months (old group). Age-matched apoE3/3 mice were employed as control group (n=3 in each group). The paraffin sections of brain tissue were stained by 2 conventional staining methods, thionin staining and hematoxylin-esion(HE) staining, the former of which was to observe the hippocampal cells, while the latter was used to examine the brain microvasculature.

RESULTS

There was no apparent difference in the cortical layer between apoE3/3 and apoE4/4 mice, neither any significant difference in the number of cells in hippocampal CA1-CA3 subfields between apoE3/3 and apoE4/4 mice at various age points (P>0.05). However, the mean size of pyramidal cells in CA1 subfield in apoE3/3 and apoE4/4 mice decreased as mice were getting older (P<0.001). At the age of 20-21 months, this cellular atrophy in apoE4/4 mice was more severe than that in old apoE3/3 mice (P<0.05). Furthermore, microvascular lesion in the thalamus was detected in all the 3 old apoE4/4 mice, at varying degrees (5.24%, 1.41% and 3.97%, respectively), while only one apoE3/3 mouse exhibited microvascular lesion in the thalamus, at a low level (0.85%).

CONCLUSION

The current study suggests that the cell size in hippocampal CA1 subfield decreases with aging, irrespective of apoE genotype. Cellular atrophy in CA1 subfield and the microvascular lesion in the thalamus are both more severe in old apoE4/4 mice as compared with those in age-matched apoE3/3 mice. Doubts still exist on whether the decreased cell size in hippocampal CA1 subfield in old apoE4/4 mice is associated with dysfunction in learning and memory and whether the microvascular lesions indicate a higher risk of stroke in human apoE4 allele mice. To clarify these issues, further investigations are needed.

Perioperative stroke in infants undergoing open heart operations for congenital heart disease

BACKGROUND

The prevalence of perioperative stroke in infants undergoing operations for congenital heart disease has not been well described. The objectives of this study were to determine the prevalence of stroke as assessed by postoperative brain magnetic resonance imaging (MRI), characterize the neuroanatomic features of focal ischemic injury, and identify risk factors for its development.

METHODS

Brain MRI was performed in 122 infants 3 to 14 days after cardiac operation with cardiopulmonary bypass, with or without deep hypothermic circulatory arrest. Preoperative, intraoperative, and postoperative data were collected. Risk factors were tested by logistic regression for univariate and multivariate associations with stroke.

RESULTS

Stroke was identified in 12 of 122 patients (10%). Strokes were preoperative in 6 patients and possibly intraoperative or postoperative in the other 6 patients, and were clinically silent except in 1 patient who had clinical seizures. Arterial-occlusive and watershed infarcts were identified with equal distribution in both hemispheres. Multivariate analysis identified lower birth weight, preoperative intubation, lower intraoperative hematocrit, and higher blood pressure at admission to the cardiac intensive care unit postoperatively as significant factors associated with stroke. Prematurity, younger age at operation, duration of cardiopulmonary bypass, and use of deep hypothermic circulatory arrest were not significantly associated with stroke.

CONCLUSIONS

The prevalence of stroke in infants undergoing operations for congenital heart disease was 10%, half of which occurred preoperatively. Most were clinically silent and undetected without neuroimaging. Mechanisms included thromboembolism and hypoperfusion, with patient-specific, procedure-specific, and postoperative contributions to increased risk.

Apolipoprotein E genotype modifies the risk of behavior problems after infant cardiac surgery

OBJECTIVE

The goal was to evaluate polymorphisms of the APOE gene as modifiers of neurobehavioral outcomes for preschool-aged children with congenital heart defects, after cardiac surgery.

METHODS

A prospective observational study with neurodevelopmental evaluation between the fourth and fifth birthdays was performed. Attention and behavioral skills were assessed through parental report.

RESULTS

Parents of 380 children completed the neurobehavioral measures. Child Behavior Checklist scores for the pervasive developmental problem scale were in the at-risk or clinically significant range for 15% of the cohort, compared with 9% for the normative data (P < .00001). Attention problem scores were in the at-risk or clinically significant range for 12% of the cohort, compared with 7% for the normative data (P = .0002). The Attention-Deficit/Hyperactivity Disorder Rating Scale-IV, Preschool Version, was completed for 378 children; 30% scored in the clinically significant range for inattention and 22% for impulsivity. After adjustment for covariates, the APOE epsilon2 allele was significantly associated with higher scores (worse problems) for multiple Child Behavior Checklist indices, including somatic complaints (P = .009), pervasive developmental problems (P = .032), and internalizing problems (P = .009). In each case, the epsilon4 allele was associated with a better outcome. APOE epsilon2 carriers had impaired social skills, compared with epsilon4 carriers (P = .009).

CONCLUSIONS

For preschool-aged children with congenital heart defects requiring surgery, parental rating scales showed an increased prevalence of restricted behavior patterns, inattention, and impaired social interactions. The APOE epsilon2 allele was associated with increased behavior problems, impaired social interactions, and restricted behavior patterns.

Significance of apolipoprotein E in subarachnoid hemorrhage: neuronal injury, repair, and therapeutic perspectives--a review

Subarachnoid hemorrhage (SAH) strikes individuals at a young age with devastating neurologic consequences. Classic formulations that correlate complications and outcome with clinical variables do not explain all the heterogeneity that is usually found in clinical practice. The role of genetic predisposition has recently been investigated. Particular attention has been paid to the apolipoprotein E (APOE) genotype that encodes for a polymorphic protein existing as 3 isoforms (apoE2, apoE3, apoE4), products of alleles E2, E3, and E4 at a single gene locus. ApoE is produced by astrocytes and exerts complex neuroprotective functions that make it a hub of the biochemical network of SAH. The neuroprotective effectiveness of the apoE4 isoform is reduced with respect to the others and this has made the E4 allele a risk factor candidate. Recently published observational studies and meta-analyses suggested that the APOE genotype may strongly improve the usual predictive model with the possibility of optimizing clinical decisions according to the individual's needs. Furthermore, the clinical results, together with new biological insights, suggest that SAH may be a possible candidate for the ongoing research on apoE-based neuroprotective therapy. This article reviews the clinical studies, analyzes their methodology, and surveys the biological links between the physiopathology of SAH and apoE and the possible prospects.

The effects of apolipoprotein E on non-impaired cognitive functioning: a meta-analysis

Nearly twice as many participants are represented in the current literature than were available at the time of the last major meta-analytic neurocognitive examination of apolipoprotein E (ApoE) epsilon allele combinations [Small, B.J., Rosnick, C.B., Fratiglioni, L., Backman, L., 2004. Apolipoprotein E and cognitive performance: a meta-analysis. Psychol. Aging 19, 592-600]. The meta-analysis in the current study sought to specifically examine (1) small effects and (2) possible moderating variables associated with ApoE allele combinations that may have been undiscoverable in previous examinations of smaller data sets. A total of 77 studies, representing 40,942 cognitively healthy adults were identified for inclusion in the current meta-analysis (random effects design). Results were congruent with the previous meta-analytic findings indicating that carriers of ApoE allele 4 (ɛ4) perform significantly worse on measures of episodic memory, executive functioning, and overall global cognitive ability. In addition, the current analysis revealed a small effect suggesting that ApoE allele 4 adversely impacts perceptual speed. In contrast to earlier studies, the results also indicate that increases in age result in significantly larger differences between ApoE ɛ4 carriers and ApoE non-ɛ4 carriers on measures of episodic memory and global cognitive ability. ApoE ɛ4 exerts broad, but specific, adverse small effects on a range of neurocognitive functions in cognitively healthy adults.

Neurological complications of cardiac surgery

Neurological injury resulting from cardiac surgery has a range of manifestations from focal neurological deficit to encephalopathy or coma. As the safety of drug-eluting stents comes into question, more patients will likely undergo coronary artery bypass graft surgery. These projections, along with the growing proportions of elderly patients and those with comorbidities, portend the potential for rising rates of perioperative neurological complications. The risk for neurological injury may be determined by the type of procedure, by patient-specific characteristics, and by the extent of cerebral embolization and hypoperfusion during and after surgery. Changes in surgical techniques, including the use of off-pump surgery, have not decreased rates of brain injury from cardiac surgery. When appropriate, modern neuroimaging techniques should be used in postoperative patients to confirm diagnosis, to provide information on potential etiology, to direct appropriate therapy, and to help in prognostication. Management of postoperative medications and early use of rehabilitation services is a recommended strategy to optimize the recovery for individuals with neurological injury after cardiac surgery.