APOE and Alzheimer disease: a major gene with semi-dominant inheritance

Apolipoprotein E (APOE) dependent lifetime risks (LTRs) for Alzheimer Disease (AD) are currently not accurately known and odds ratios alone are insufficient to assess these risks. We calculated AD LTR in 7351 cases and 10 132 controls from Caucasian ancestry using Rochester (USA) incidence data. At the age of 85 the LTR of AD without reference to APOE genotype was 11% in males and 14% in females. At the same age, this risk ranged from 51% for APOE44 male carriers to 60% for APOE44 female carriers, and from 23% for APOE34 male carriers to 30% for APOE34 female carriers, consistent with semi-dominant inheritance of a moderately penetrant gene. Using PAQUID (France) incidence data, estimates were globally similar except that at age 85 the LTRs reached 68 and 35% for APOE 44 and APOE 34 female carriers, respectively. These risks are more similar to those of major genes in Mendelian diseases, such as BRCA1 in breast cancer, than those of low-risk common alleles identified by recent GWAS in complex diseases. In addition, stratification of our data by age groups clearly demonstrates that APOE4 is a risk factor not only for late-onset but for early-onset AD as well. Together, these results urge a reappraisal of the impact of APOE in Alzheimer disease.

EFNS guidelines for the diagnosis and management of Alzheimer's disease

BACKGROUND AND OBJECTIVES

In 2008 a task force was set up to develop a revision of the European Federation of the Neurological Societies (EFNS) guideline for the diagnosis and management of Alzheimer's disease (AD) and other disorders associated with dementia, published in early 2007. The aim of this revised international guideline was to present a peer-reviewed evidence-based statement for the guidance of practice for clinical neurologists, geriatricians, psychiatrists, and other specialist physicians responsible for the care of patients with AD. Mild cognitive impairment and non-Alzheimer dementias are not included in this guideline.

METHODS

The task force working group reviewed evidence from original research articles, meta-analysis, and systematic reviews, published before May 2009. The evidence was classified and consensus recommendations graded (A, B, or C) according to the EFNS guidance. Where there was a lack of evidence, but clear consensus, good practice points were provided.

RESULTS

The recommendations for clinical diagnosis, blood tests, neuropsychology, neuroimaging, electroencephalography, cerebrospinal fluid (CSF) analysis, genetic testing, disclosure of diagnosis, treatment of AD, behavioural and psychological symptoms in dementia, legal issues, counselling and support for caregivers were all revised as compared with the previous EFNS guideline.

CONCLUSION

A number of new recommendations and good practice points are made, namely in CSF, neuropsychology, neuroimaging and reviewing non-evidence based therapies. The assessment, interpretation, and treatment of symptoms, disability, needs, and caregiver stress during the course of AD require the contribution of many different professionals. These professionals should adhere to these guideline to improve the diagnosis and management of AD.

Alzheimer's disease: genetic basis and amyloid imaging as endophenotype

To date, all known Alzheimer's disease genes influence amyloid β (Aβ). Imaging of Aβ deposition in the human brain using positron emission tomography (PET) tracers as [11C]Pittsburgh Compound B ([(11)C]PiB) or [18F]FDDNP offers the possibility of using cortical tracer binding as a quantitative endophenotype for genetic studies of late-onset Alzheimer's disease (AD). In this review we investigate the association between cerebral Aβ burden, as measured by amyloid PET imaging, and different genetic risk factors involved in AD. Through a look at the major genetic risk factors for both early-onset familial and late-onset sporadic forms of AD, we discuss the possible role of amyloid PET imaging as an endophenotype in AD. Several PET studies confirmed the high heritability of amyloid load estimated by PET imaging and its association with the major genetic risk factors for early and late onset AD, suggesting that cerebral binding of these amyloid tracers could represent an useful trait for large-scale genetic studies of AD.

IgM monoclonal gammopathy-associated neuropathies with different IgM specificity

BACKGROUND AND PURPOSE

  Antibodies directed against myelin-associated glycoprotein (MAG) are believed to be the most frequent biologic marker of the neuropathies associated with IgM monoclonal gammopathy of undetermined significance (MGUS). The objective of this study was to examine the prevalence of antiganglioside and/or sulfatide-positive patients and their clinical findings, including therapeutic response, compared to anti-MAG-positive or seronegative patients.

METHODS

  We prospectively followed 46 patients with MGUS who were diagnosed in our tertiary referral centers for polyneuropathy since 1997. All patients underwent nerve conduction studies and were tested for anti-MAG, gangliosides, and sulfatide antibodies. All the anagraphic and clinical data (including symptoms, disability scale, therapy, secondary malignancy development) were recorded in a database and compared between three patients' groups (anti-MAG-positive; antiganglioside/sulfatide-positive; no reactivity).

RESULTS

  Anti-MAG reactivity was present in 17 (37%) patients; other 17 patients (37%) had antiganglioside/sulfatide reactivity and 12 (26%) had no reactivity. Patients with antiganglioside/sulfatide positivity, although heterogeneous by a clinical and neurophysiological point of view, had the most severe neuropathic manifestations and a higher disability score at nadir (P < 0.001). These patients had a better response to both intravenous immunoglobulin therapy and rituximab.

CONCLUSIONS

  Our results suggest that antiganglioside/sulfatide-positive patients form a relevant portion of patients with MGUS-associated polyneuropathy seen in tertiary care centers and should be considered in future studies on treatment response.

Worldwide distribution of PSEN1 Met146Leu mutation: a large variability for a founder mutation

OBJECTIVE

Large kindreds segregating familial Alzheimer disease (FAD) offer the opportunity of studying clinical variability as observed for presenilin 1 (PSEN1) mutations. Two early-onset FAD (EOFAD) Calabrian families with PSEN1 Met146Leu (ATG/CTG) mutation constitute a unique population descending from a remote common ancestor. Recently, several other EOFAD families with the same mutation have been described worldwide.

METHODS

We searched for a common founder of the PSEN1 Met146Leu mutation in families with different geographic origins by genealogic and molecular analyses. We also investigated the phenotypic variability at onset in a group of 50 patients (mean age at onset 40.0 +/- 4.8 years) by clinical, neuropsychological, and molecular methodologies.

RESULTS

EOFAD Met146Leu families from around the world resulted to be related and constitute a single kindred originating from Southern Italy before the 17th century. Phenotypic variability at onset is broad: 4 different clinical presentations may be recognized, 2 classic for AD (memory deficits and spatial and temporal disorientation), whereas the others are expressions of frontal impairment. The apathetic and dysexecutive subgroups could be related to orbital-medial prefrontal cortex and dorsolateral prefrontal cortex dysfunction.

CONCLUSIONS

Genealogic and molecular findings provided evidence that the PSEN1 Met146Leu families from around the world analyzed in this study are related and represent a single kindred originating from Southern Italy. The marked phenotypic variability might reflect early involvement by the pathologic process of different cortical areas. Although the clinical phenotype is quite variable, the neuropathologic and biochemical characteristics of the lesions account for neurodegenerative processes unmistakably of Alzheimer nature.

ApolipoproteinE epsilon 4 allele is not associated with disease course and severity in multiple sclerosis

BACKGROUND

No study has assessed the association between apolipoproteinE (APOE) and multiple sclerosis (MS) forms grouped by also taking into account cognitive performance.

AIMS OF THE STUDY

To assess the relationship between APOE and disease course, particularly focusing on benign MS (BMS), defined as also including cognitive preservation.

METHODS

In 173 consecutive patients, we assessed the association between APOE and MS course and severity.

RESULTS

Twenty-nine APOE-epsilon4 carriers were identified. The epsilon4 allele was not associated with BMS. Moreover, it was associated neither with other disease courses nor with the time to reach disability milestones and secondary progression.

CONCLUSION

Although plausible, the association between APOE and MS course (particularly with BMS defined by including cognitive preservation) and disease severity remains controversial.

A short version of Rao's Brief Repeatable Battery as a screening tool for cognitive impairment in multiple sclerosis

Rao's Brief Repeatable Battery (BRB) is the most widely used instrument for cognitive evaluation in multiple sclerosis (MS). We assessed a short version of the BRB in 116 relapsing-remitting participants. We found that the administration of three tests, the Selective Reminding Test, the Paced Auditory Serial Addition Test-3 seconds and the Symbol Digit Modalities Test, was able to detect cognitive impairment with a sensitivity of 94%, a specificity of 84%, and an accuracy of 89%. On the basis of these results we developed a screening algorithm requiring 5 to 15 minutes, which may represent a highly sensitive and rapid tool to detect MS-associated cognitive impairment.

Mild cognitive impairment: loss of linguistic task-induced changes in motor cortex excitability

BACKGROUND

In amnestic mild cognitive impairment (aMCI), functional neuronal connectivity may be altered, as suggested by quantitative EEG and neuroimaging data. In young healthy humans, the execution of linguistic tasks modifies the excitability of the hand area of the dominant primary motor cortex (M1(hand)), as tested by transcranial magnetic stimulation (TMS). We used TMS to investigate functional connectivity between language-related cortical areas and M1(hand) in aMCI.

METHODS

Ten elderly women with aMCI and 10 age-matched women were recruited. All participants were right handed and underwent a neuropsychological evaluation. In the first TMS experiment, participants performed three different tasks: reading aloud, viewing of non-letter strings (baseline), and nonverbal oral movements. The second experiment included the baseline condition and three visual searching/matching tasks using letters, geometric shapes, or digits as target stimuli.

RESULTS

In controls, motor evoked potentials (MEP) elicited by suprathreshold TMS of the left M1(hand) were significantly larger during reading aloud (170% baseline) than during nonverbal oral movements, whereas no difference was seen for right M1(hand) stimulation. Similarly, MEP elicited by left M1(hand) stimulation during letter and shape searching/matching tasks were significantly larger compared to digit task. In contrast, linguistic task performance did not produce any significant MEP modulation in patients with aMCI, although neuropsychological evaluation showed normal language abilities.

CONCLUSIONS

Findings suggest that functional connectivity between the language-related brain regions and the dominant M1(hand) may be altered in amnestic mild cognitive impairment. Follow-up studies will reveal whether transcranial magnetic stimulation application during linguistic tasks may contribute to characterize the risk of conversion to Alzheimer disease.

The contribution of cerebrospinal fluid oligoclonal bands to the early diagnosis of multiple sclerosis

Background

McDonald Criteria (MDC) have been validated in selected patients at high risk for multiple sclerosis (MS). However, possible overdiagnosis of MS can represent critical issues in less controlled clinical settings.

Objective

To assess the contribution of oligoclonal bands (OB) to MS diagnosis in current clinical practice.

Methods

We included all the patients admitted to our Department since 2001 who had undergone diagnostic workup for a possible MS diagnosis, followed up for at least 1 year. We assessed the accuracy of MDC, OB, and two MDC definitions of dissemination in space (DIS-MRI: fulfillment of MRI criteria, DIS-OB: two MRI lesions+OB).

Results

We included 118 patients (median follow-up 4.0 years). Twenty-eight cases received an alternative diagnosis, whereas none of these presented OB, 43% fulfilled the DIS-MRI criteria. OB were present in 70% of the remaining 90 patients. By the end of the follow-up, 56% of the diagnoses had converted to clinically definite MS and OB showed higher accuracy than DIS-MRI fulfillment (70% vs 58%). Moreover, after 1 year and at the end of the follow-up, DIS-OB yielded a higher Specificity level in comparison with DIS-MRI.

Conclusion

OB can improve overall diagnostic Accuracy by increasing Specificity and negative predictive value.

Glucocorticoid Receptor Gene Polymorphisms in Italian Patients with Anorexia and Bulimia Nervosa

The etiopathogenesis of eating disorders (ED) is complex and poorly understood. The hypothalamic-pituitary-adrenal (HPA) axis, involved in the biological response to stress, could influence the onset and the course of ED.) Several variants in the Glucocorticoid receptor (GR) gene have been related to different metabolic parameters suggesting a possible role in ED. We studied if genetic variants of GR could represent potential risk factors for the development of Anorexia Nervosa (AN) and Bulimia Nervosa (BN).

We investigated the distribution of several single nucleotide polymorphisms (SNPs) of the GR including N363S (rs6195), Er22/23EK (rs6189-6190), A/G SNP in exon 9beta (rs6198) and the intronic BclI polymorphism (rs41423247), in 118 Italian patients affected by AN and in 108 patients with BN. Moreover we studied 116 normal individuals and 177 obese subjects. The distributions of genotypes and allele frequency of the SNPs in all studied groups followed Hardy-Weinberg equilibrium and did not significantly differ from that of controls. A trend towards association was observed in case-control association analysis (p=0.07) for rs6198. A correlation of metabolic parameters to the GR genotypes was performed.

We report the analysis of different GR SNPs for the first time in Italian patients with AN and BN. We failed to detect an allelic association between the studied SNPs in the GR gene and AN and BN.

None of the variants seems to influence these pathologies, not supporting a role for the GR gene as genetic risk factors for ED.

Education and occupation as proxies for reserve in aMCI converters and AD: FDG-PET evidence

BACKGROUND

Previous reports have shown that higher education is associated with more severe brain pathology in patients with Alzheimer disease (AD), suggesting that these individuals have a functional reserve provided by education, which masks the clinical expression of a higher degree of neurodegeneration. It is unknown if a similar reserve mechanism exists in patients with amnestic mild cognitive impairment (aMCI). The aim of this study was to assess the impact of education and occupation on brain glucose metabolism (rCMRglc) measured with FDG-PET in aMCI and in a very large sample of subjects with probable AD (pAD).

METHODS

A total of 242 patients with pAD, 72 with aMCI, and 144 healthy controls participated in the study. At follow-up, 21 subjects with aMCI progressed to AD. A regression analysis was conducted (SPM2), with education and occupation as independent variables, and rCMRglc as dependent variable, adjusting for demographic data, global cognitive status, and neuropsychological scores.

RESULTS

The analysis showed a significant association between higher education/occupation and lower rCMRglc in posterior temporoparietal cortex and precuneus in pAD and aMCI converters, and no correlation in aMCI nonconverters and healthy controls. This means that, when submitted to FDG-PET for diagnostic evaluation, pAD and aMCI converters with higher education/occupation had, for comparable cognitive impairment, a more severe rCMRglc reduction than the ones with lower education/occupation.

CONCLUSIONS

This study suggests that education and occupation may be proxies for brain functional reserve, reducing the severity and delaying the clinical expression of Alzheimer disease (AD) pathology. The results in aMCI converters suggest that functional reserve is already at play in the predementia phase of AD.

A comparison of unawareness in frontotemporal dementia and Alzheimer's disease

BACKGROUND

Loss of insight is a core diagnostic feature of frontotemporal dementia (FTD) and anosognosia is frequently reported in Alzheimer's disease (AD).

AIM

To compare unawareness (anosognosia) for different symptoms, measured with a discrepancy score between patient's and caregiver's assessment, in AD and FTD.

METHOD

In a prospective, multi-centre study, 123 patients with probable AD, selected according to the NINCDS-ADRDA procedure, were matched for age, sex, education, disease duration and dementia severity to patients with FTD (n = 41), selected according to international consensus criteria. A research complaint questionnaire was used to obtained patient's and caregiver's assessment concerning neuropsychological and behavioural symptoms. Data were compared in each group and between groups. Unawareness (measured by discrepancy scores) was compared between patients with AD and FTD.

RESULTS

The caregivers generally assessed symptoms more severely than did patients, but both patient groups reported changes in affect (depressive mood or irritability) as their caregivers did. Unawareness was greater in patients with FTD than in patients with AD for language and executive difficulties, and for changes in behaviour and daily activities.

CONCLUSION

The main finding is that unawareness was observed in both patients with FTD and patients with AD for most clinical domains. However, qualitative and quantitative differences showed that lack of awareness was greater in patients with FTD.

Influence of impaired T- and B-cell compartments on efficacy of IVIg in dysimmune neuropathies

Autoimmune mechanisms are postulated to play a role in the development and progression of dysimmune neuropathies (DN). We investigated the relation between lymphocyte number and marker expression, and disease activity in 20 patients with DN under intravenous immunoglobulins (IVIg) treatment. B- and T-lymphocyte markers were studied by flow cytometry of the expression of CD5, CD25, CD23 and CD38 markers on B cells and of CD3, CD4 and CD8 markers, respectively. These parameters were compared with those obtained from matched healthy volunteers. The proportions of CD38+ B cells were higher in patients compared with those of controls. Proportions of activated CD4+ and CD8+ T cells were comparable in peripheral blood mononuclear cells of patients and controls, but a significant reduction of the absolute numbers of CD3+, CD4+ and CD8+ cells were observed in DN patients. The percentages of CD25+ memory T cells were instead significantly increased in DN patients. Lastly, T-cell reduction and the CD19/CD38 ratio over total B (CD19+) cells directly correlated with a poor response to IVIg therapy. In DN, whereas T-cell number is reduced, activated T and B cells are increased, thus suggesting an intrinsic defect of the immune response.

Metabolic correlates of executive dysfunction

This study was designed to examine the correlations between resting-state brain glucose metabolism (CMRglc), as measured with Positron Emission Tomography and performance on executive function tasks in Alzheimer's disease (AD), while taking into account the severity of cognitive deterioration. We addressed this issue in 50 AD patients, classified as very mild (n = 22) and mild (n = 28) AD on the basis of an extensive neuropsychological battery. Thirteen healthy subjects were selected as controls for the neuropsychological measures. Statistical Parametric Mapping (SPM) was used to examine voxel-wise correlations between CMRglc and scores on selected cognitive tests of executive functions: the Stroop Test, the Trail Making Test, the Dual Task and the Phonemic Fluency, while correcting for age and global CMRglc. All analyses were done separately for the two AD subgroups. The very mild AD patients showed significant associations between Stroop and Trail Making Test scores and prefrontal regions metabolism, whereas the mild AD patients exhibited more widely distributed cognitive-metabolic correlations extending to the posterior brain regions. These data suggest that a large cortical network is implicated in executive dysfunction in AD, and that the pattern of cognitive-metabolic correlations varies according to disease severity.