ApoE genotype and cognition after subarachnoid haemorrhage: a longitudinal study

Three major effects of APOEε4 on Aβ immunotherapy induced ARIA

The targeting of amyloid-beta (Aβ) plaques therapeutically as one of the primary causes of Alzheimer's disease (AD) dementia has been an ongoing effort spanning decades. While some antibodies are extremely promising and have been moved out of clinical trials and into the clinic, most of these treatments show similar adverse effects in the form of cerebrovascular damage known as amyloid-related imaging abnormalities (ARIA). The two categories of ARIA are of major concern for patients, families, and prescribing physicians, with ARIA-E presenting as cerebral edema, and ARIA-H as cerebral hemorrhages (micro- and macro-). From preclinical and clinical trials, it has been observed that the greatest genetic risk factor for AD, APOEε4, is also a major risk factor for anti-Aβ immunotherapy-induced ARIA. APOEε4 carriers represent a large population of AD patients, and, therefore, limits the broad adoption of these therapies across the AD population. In this review we detail three hypothesized mechanisms by which APOEε4 influences ARIA risk: (1) reduced cerebrovascular integrity, (2) increased neuroinflammation and immune dysregulation, and (3) elevated levels of CAA. The effects of APOEε4 on ARIA risk is clear, however, the underlying mechanisms require more research.

Diabetes Mellitus and Amyotrophic Lateral Sclerosis: A Systematic Review

BACKGROUND

Amyotrophic Lateral Sclerosis (ALS) is a degenerative disorder which affects the motor neurons. Growing evidence suggests that ALS may impact the metabolic system, including the glucose metabolism. Several studies investigated the role of Diabetes Mellitus (DM) as risk and/or prognostic factor. However, a clear correlation between DM and ALS has not been defined. In this review, we focus on the role of DM in ALS, examining the different hypotheses on how perturbations of glucose metabolism may interact with the pathophysiology and the course of ALS.

METHODS

We undertook an independent PubMed literature search, using the following search terms: ((ALS) OR (Amyotrophic Lateral Sclerosis) OR (Motor Neuron Disease)) AND ((Diabetes) OR (Glucose Intolerance) OR (Hyperglycemia)). Review and original articles were considered.

RESULTS

DM appears not to affect ALS severity, progression, and survival. Contrasting data suggested a protective role of DM on the occurrence of ALS in elderly and an opposite effect in younger subjects.

CONCLUSIONS

The actual clinical and pathophysiological correlation between DM and ALS is unclear. Large longitudinal prospective studies are needed. Achieving large sample sizes comparable to those of common complex diseases like DM is a challenge for a rare disease like ALS. Collaborative efforts could overcome this specific issue.

Genetics and Genomics of Acute Neurologic Disorders

Neurologic diseases and injuries are complex and multifactorial, making risk prediction, targeted treatment modalities, and outcome prognostication difficult and elusive. Genetics and genomics have affected clinical practice in many aspects in medicine, particularly cancer treatment. Advancements in knowledge of genetic and genomic variability in neurologic disease and injury are growing rapidly. Although these data are not yet ready for use in clinical practice, research continues to progress and elucidate information that eventually will provide answers to complex neurologic questions and serve as a platform to provide individualized care plans aimed at improving outcomes. This article provides a focused review of relevant literature on genetics, genomics, and common complex neurologic disease and injury likely to be seen in the acute care setting.

Biomarkers as outcome predictors in subarachnoid hemorrhage--a systematic review

CONTEXT

Subarachnoid hemorrhage (SAH) has a high fatality rate and many suffer from delayed neurological deficits. Biomarkers may aid in the identification of high-risk patients, guide treatment/management and improve outcome.

OBJECTIVE

The aim of this review was to summarize biomarkers of SAH associated with outcome.

METHODS

An electronic database query was completed, including an additional review of reference lists to include all potential human studies.

RESULTS

A total of 298 articles were identified; 112 were reviewed; 55 studies were included.

CONCLUSION

This review details biomarkers of SAH that correlate with outcome. It provides the basis for research investigating their possible translation into the management of SAH patients.

ApoE E4 is a susceptibility factor in amnestic but not aphasic dementias

The goal of this study was to determine if the apolipoprotein ε gene, which is a well-established susceptibility factor for Alzheimer disease (AD) pathology in typical amnestic dementias, may also represent a risk factor in the language-based dementia, primary progressive aphasia (PPA). Apolipoprotein E genotyping was obtained from 149 patients with a clinical diagnosis of PPA, 330 cognitively healthy individuals (NC), and 179 patients with a clinical diagnosis of probable Alzheimer's disease (PrAD). Allele frequencies were compared among the groups. Analyses were also completed by sex and in 2 subsets of PPA patients: 1 in which the patients were classified by subtype (logopenic, agrammatic, and semantic) and another in which pathologic data were available. The allele frequencies for the PPA group (ε2:5%, ε3:79.5%, and ε4:15.4%) showed a distribution similar to the NC group, but significantly different from the PrAD group. The presence of an ε4 allele did not influence the age of symptom onset or aid in the prediction of AD pathology in PPA. These data show that ε4 polymorphism, which is a well-known risk factor for AD pathology in typical amnestic dementias, has no similar relationship to the clinical syndrome of PPA or its association with AD pathology.

Association of apolipoprotein E polymorphisms with cerebral vasospasm after spontaneous subarachnoid hemorrhage

Cerebral vasospasm (CVS) is the main complication of spontaneous subarachnoid hemorrhage (SAH), severely affecting clinical outcome of patients with SAH. Apolipoprotein E gene (APOE) is associated with prognosis of spontaneous subarachnoid hemorrhage (SAH), and APOEε4 allele is reported to be apt to CVS after SAH. The current study aimed to investigate the association of APOE polymorphisms with CVS after SAH. One hundred and eighty-five patients with spontaneous SAH were recruited in the study. APOE genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). CVS was judged by Transcranial Doppler sonography (TCD) combined with patients' condition. χ2-test and logistic regression analysis were done by SPSS (version 11.5). The distributions of APOE genotypes and alleles matched Hardy-Weinberg Law. In 185 patients, 21 of 32 (65.7%) patients with APOEε4 allele showed CVS, which was significantly different from those without APOE ε4 allele (56 of 153 patients, 36.6%, P=0.022). However, neither the presence of ε2 nor ε3 was significantly different from those absent of it (P>0.05). Logistic regression analysis demonstrated that ApoEε4 allele was a risk factor (OR=2.842. 95% CI 1.072-6.124. P=0.019) to predispose to CVS after adjusting for age, sex, hypertension or not, hyperlipemia or not, Fisher grade, and Hunt-Hess grade after SAH. Our finding suggests that the patients with APOEε4 allele predispose to CVS after spontaneous SAH.

Does apolipoprotein E genotype modify the clinical expression of ALS?

BACKGROUND

The presence of the apolipoprotein E (ApoE) 4 genotype is associated with an earlier age of onset for Alzheimer's disease (AD) and several other neurodegenerative disorders. The objective of this study was to investigate the effect of ApoE genotypes on the clinical course of amyotrophic lateral sclerosis (ALS).

METHODS

Eight hundred and fifty-two consecutive patients with sporadic ALS evaluated at a tertiary care center were investigated for the effect of ApoE genotype on age of onset, rate of motor disease progression, cognitive functioning, and survival in ALS.

RESULTS

The frequencies of individual ApoE genotypes did not differ between patients with ALS and ALS-free Caucasian populations. Patients with different ApoE genotypes did not differ in the age of onset for ALS (years) (ApoE2 = 57.8 ± 13.7, ApoE3 = 57.3 ± 13.7, ApoE4 = 57.7 ± 13.2; P = 0.97), the rate of disease progression (Appel ALS score/month) (ApoE2 = 2.91 ± 2.66, ApoE3 = 2.67 ± 2.66, ApoE4 = 2.61 ± 2.47; P = 0.89), cognitive status (% cognitively impaired) (ApoE2 = 31.7, ApoE3 = 26.8, ApoE4 = 34.3, P = 0.28), or survival in years (ApoE2 = 3.79 ± 3.70, ApoE3 = 3.17 ± 2.27, ApoE4 = 3.05 ± 1.75; P = 0.85).

CONCLUSIONS

Our results suggest that ApoE genotype does not modify clinical course of sporadic ALS, in stark contrast to the influence of ApoE genotype on the disease course of AD and other neurodegenerative disorders.

Natural history and medical treatment of cognitive dysfunction after spontaneous subarachnoid haemorrhage: review of current literature with respect to aneurysm treatment

Aneurysmal subarachnoid haemorrhage (aSAH) has the highest mortality and morbidity among all types of stroke. Unfortunately, cognitive dysfunction remains a major problem to those who survive the acute crisis. Most studies focused on patients after microsurgical clipping, which turned out to be different from the modern patient cohorts. With the widespread introduction of endovascular surgery as the first choice of treatment, there was a hope that post-aSAH cognitive dysfunction could be markedly reduced. However, data showed that post-aSAH cognitive dysfunction remained a major burden to the survivors of our modern patient cohort that returned to the community more than nine months after the initial haemorrhage. There is, therefore, a need to further understand its pathophysiology and natural history, and to develop effective treatment strategy. The results are encouraging and further clinical studies are indicated. Collaborations between cognitive scientists, neurologists and neurosurgeons are essential to advance the understanding of the problem.

Putative mechanisms of cognitive dysfunction in chemotherapy-naïve diffuse large B-cell lymphoma: a case report and review of the literature

Cognitive impairment is now recognized as a frequent consequence of treatments for cancers localized outside the central nervous system (CNS). In contrast, little attention has been given to the potentially deleterious cognitive effects from non-CNS cancers themselves. The present case study proposes that cognitive deficits occur in a subset of treatment-naive patients with diffuse large B-cell lymphoma in whom no gross evidence of lymphoma-related CNS involvement is apparent. Evidence is presented from a case study and elaborate putative mechanisms centering on deleterious effects of B-cell-mediated inflammatory cytokine secretion on neurons. Moreover, this case study speculates that genetic variability involving apolipoprotein E or other factors may mediate cognitive variability among these patients.

Genetic determinants of cerebral vasospasm, delayed cerebral ischemia, and outcome after aneurysmal subarachnoid hemorrhage

Despite extensive effort to elucidate the cellular and molecular bases for delayed cerebral injury after aneurysmal subarachnoid hemorrhage (aSAH), the pathophysiology of these events remains poorly understood. Recently, much work has focused on evaluating the genetic underpinnings of various diseases in an effort to delineate the contribution of specific molecular pathways as well as to uncover novel mechanisms. The majority of subarachnoid hemorrhage genetic research has focused on gene expression and linkage studies of these markers as they relate to the development of intracranial aneurysms and their subsequent rupture. Far less work has centered on the genetic determinants of cerebral vasospasm, the predisposition to delayed cerebral injury, and the determinants of ensuing functional outcome after aSAH. The suspected genes are diverse and encompass multiple functional systems including fibrinolysis, inflammation, vascular reactivity, and neuronal repair. To this end, we present a systematic review of 21 studies suggesting a genetic basis for clinical outcome after aSAH, with a special emphasis on the pathogenesis of cerebral vasospasm and delayed cerebral ischemia. In addition, we highlight potential pitfalls in the interpretation of genetic association studies, and call for uniformity of design of larger multicenter studies in the future.

The associations of apolipoprotein E and angiotensin-converting enzyme polymorphisms and cognitive function in Type 1 diabetes based on an 18-year follow-up of the DCCT cohort

AIMS

Specific polymorphisms of the apolipoprotein E (APOE) and angiotensin-converting enzyme (ACE) genes appear to increase risk for Alzheimer's disease and cognitive dysfunction in the general population, yet little research has examined whether genetic factors influence risk of cognitive dysfunction in patients with Type 1 diabetes. The long-term follow-up of the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) population provides an opportunity to examine if specific genetic variations in APOE and ACE alter risk for cognitive decline.

METHODS

Neurocognitive function in Type 1 diabetic subjects from the DCCT/EDIC study was assessed at DCCT entry and re-assessed approximately 18 years later, using a comprehensive cognitive test battery. Glycated haemoglobin (HbA(1c)) and the frequency of severe hypoglycaemic events leading to coma or seizures were measured over the 18-year follow-up. We determined whether the APO epsilon4 and ACE intron 16 indel genotypes were associated with baseline cognitive function and with change over time, and whether they conferred added risk in those subjects experiencing severe hypoglycaemic events or greater glycaemic exposure.

RESULTS

None of the APOE or ACE polymorphisms were associated with either baseline cognitive performance or change in cognition over the 18-year follow-up. Moreover, none of the genotype variations altered the risk of cognitive dysfunction in those subjects with severe hypoglycaemic episodes or high HbA(1c).

CONCLUSIONS

In this sample of young and middle-aged adults with Type 1 diabetes, APO epsilon4 and ACE D alleles do not appear to increase risk of cognitive dysfunction.

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.

Apolipoprotein E epsilon4 is associated with disease-specific effects on brain atrophy in Alzheimer's disease and frontotemporal dementia

Apolipoprotein epsilon4 (apoE4) has been strongly linked with Alzheimer's disease (AD) and contributes to several other neurological disorders. We investigated the influence of epsilon4 allele carrier status on the pattern of gray matter atrophy and disease severity in 51 patients with probable AD and 31 patients with behavioral variant frontotemporal dementia (bvFTD), compared with 56 healthy controls. Voxel-based morphometry was performed by using statistical parametric mapping. The epsilon4 allele frequency was higher in the AD group (P < 0.001) than the controls but not in the bvFTD group. No differences in demographic or cognitive profiles were observed between epsilon4 allele carriers and noncarriers within any of the diagnostic groups. However, epsilon4 carrier status was associated with more severe brain atrophy in disease-specific regions compared with noncarriers in both AD and bvFTD. AD epsilon4 carriers showed greater atrophy in the bilateral parietal cortex and right hippocampus, and bvFTD epsilon4 carriers demonstrated greater atrophy in the bilateral medial, dorsolateral, and orbital frontal cortex, anterior insula, and cingulate cortex with right predominance. This regional epsilon4 effect is consistent with the hypothesis that apoE may affect the morphologic expression uniquely in different neurodegenerative diseases. The atrophy patterns in epsilon4 carriers may indicate that they are at greater risk for clinical progression.

Psychosocial and neurocognitive performance after spontaneous nonaneurysmal subarachnoid hemorrhage related to the APOE-ε4 genotype: a prospective 5-year follow-up study

Object

In this study, the authors prospectively evaluated long-term psychosocial and neurocognitive performance in patients suffering from nonaneurysmal, nontraumatic subarachnoid hemorrhage (SAH) and investigated the association between the APOE-ε4 genotype and outcome in these patients.

Methods

All patients admitted to the authors' institution between January 2001 and January 2003 with spontaneous nonaneurysmal SAH were prospectively examined (mean follow-up 59.8 months). The APOE genotype was determined in all patients by polymerase chain reaction from a blood sample. Of the 30 patients included in this study, 11 were carriers of the ε4 allele.

Results

All patients showed a good recovery and regained full independence with no persisting neurological deficits. The patients with the ε4 allele, however, scored significantly higher on the Beck Depression Inventory (22.1 ± 6.3 vs 14.1 ± 5.1). At follow-up, depression was more persistent in the group with the ε4 allele compared with the group that lacked the allele. This finding reached statistical significance (p < 0.05). Selective attention was impaired in all patients during the first year of follow-up, with an earlier recovery noted in the patients without the ε4 allele. Moreover, there was a tendency toward a linear relationship between the Beck Depression Inventory and the d2 Test of Attention. Two patients who carried the ε4 allele did not return to their employment even after 5 years.

Conclusions

The findings in this study suggest that the APOE genotypes may be associated with the psychosocial and neurocognitive performance after spontaneous nonaneurysmal SAH, even in the absence of neurological impairment. Physicians should consider patient genotype in assessing the long-term consequences of nonaneurysmal SAH.

Subarachnoid hemorrhage: tests of association with apolipoprotein E and elastin genes

Background

Apolipoprotein E (APOE) and elastin (ELN) are plausible candidate genes involved in the pathogenesis of stroke. We tested for association of variants in APOE and ELN with subarachnoid hemorrhage (SAH) in a population-based study. We genotyped 12 single nucleotide polymorphisms (SNPs) on APOE and 10 SNPs on ELN in a sample of 309 Caucasian individuals, of whom 107 are SAH cases and 202 are age-, race-, and gender-matched controls from the Greater Cincinnati/Northern Kentucky region. Associations were tested at genotype, allele, and haplotype levels. A genomic control analysis was performed to check for spurious associations resulting from population substructure.

Results

At the APOE locus, no individual SNP was associated with SAH after correction for multiple comparisons. Haplotype analysis revealed significant association of the major haplotype (Hap1) in APOE with SAH (p = 0.001). The association stemmed from both the 5' promoter and the 3' region of the APOE gene. APOE ε2 and ε 4 were not significantly associated with SAH. No association was observed for ELN at genotype, allele, or haplotype level and our study failed to confirm previous reports of ELN association with aneurysmal SAH.

Conclusion

This study suggests a role of the APOE gene in the etiology of aneurysmal SAH.