Apolipoprotein E (APOE) dependent lifetime risks (LTRs) for Alzheimer Disease (AD) are currently not accurately known and odds ratios (ORs) alone are insufficient to assess these risks. We calculated AD lifetime risk in 7,351 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.

Based on the recent literature and collective experience, an international consortium developed revised guidelines for the diagnosis of behavioural variant frontotemporal dementia. The validation process retrospectively reviewed clinical records and compared the sensitivity of proposed and earlier criteria in a multi-site sample of patients with pathologically verified frontotemporal lobar degeneration. According to the revised criteria, ‘possible’ behavioural variant frontotemporal dementia requires three of six clinically discriminating features (disinhibition, apathy/inertia, loss of sympathy/empathy, perseverative/compulsive behaviours, hyperorality and dysexecutive neuropsychological profile). ‘Probable’ behavioural variant frontotemporal dementia adds functional disability and characteristic neuroimaging, while behavioural variant frontotemporal dementia ‘with definite frontotemporal lobar degeneration’ requires histopathological confirmation or a pathogenic mutation. Sixteen brain banks contributed cases meeting histopathological criteria for frontotemporal lobar degeneration and a clinical diagnosis of behavioural variant frontotemporal dementia, Alzheimer’s disease, dementia with Lewy bodies or vascular dementia at presentation. Cases with predominant primary progressive aphasia or extra-pyramidal syndromes were excluded. In these autopsy-confirmed cases, an experienced neurologist or psychiatrist ascertained clinical features necessary for making a diagnosis according to previous and proposed criteria at presentation. Of 137 cases where features were available for both proposed and previously established criteria, 118 (86%) met ‘possible’ criteria, and 104 (76%) met criteria for ‘probable’ behavioural variant frontotemporal dementia. In contrast, 72 cases (53%) met previously established criteria for the syndrome (P < 0.001 for comparison with ‘possible’ and ‘probable’ criteria). Patients who failed to meet revised criteria were significantly older and most had atypical presentations with marked memory impairment. In conclusion, the revised criteria for behavioural variant frontotemporal dementia improve diagnostic accuracy compared with previously established criteria in a sample with known frontotemporal lobar degeneration. Greater sensitivity of the proposed criteria may reflect the optimized diagnostic features, less restrictive exclusion features and a flexible structure that accommodates different initial clinical presentations. Future studies will be needed to establish the reliability and specificity of these revised diagnostic guidelines.

Background

We have followed-up on the recent genome-wide association (GWA) of the clusterin gene (CLU) with increased risk for Alzheimer disease (AD), by performing an unbiased resequencing of all CLU coding exons and regulatory regions in an extended Flanders-Belgian cohort of Caucasian AD patients and control individuals (n = 1930). Moreover, we have replicated genetic findings by targeted resequencing in independent Caucasian cohorts of French (n = 2182) and Canadian (n = 573) origin and by performing meta-analysis combining our data with previous genetic CLU screenings.

Results

In the Flanders-Belgian cohort, we identified significant clustering in exons 5-8 of rare genetic variations leading to non-synonymous substitutions and a 9-bp insertion/deletion affecting the CLU β-chain (p = 0.02). Replicating this observation by targeted resequencing of CLU exons 5-8 in 2 independent Caucasian cohorts of French and Canadian origin identified identical as well as novel non-synonymous substitutions and small insertion/deletions. A meta-analysis, combining the datasets of the 3 cohorts with published CLU sequencing data, confirmed that rare coding variations in the CLU β-chain were significantly enriched in AD patients (ORMH = 1.96 [95% CI = 1.18-3.25]; p = 0.009). Single nucleotide polymorphisms (SNPs) association analysis indicated the common AD risk association (GWA SNP rs11136000, p = 0.013) in the 3 combined datasets could not be explained by the presence of the rare coding variations we identified. Further, high-density SNP mapping in the CLU locus mapped the common association signal to a more 5' CLU region.

Conclusions

We identified a new genetic risk association of AD with rare coding CLU variations that is independent of the 5' common association signal identified in the GWA studies. At this stage the role of these coding variations and their likely effect on the β-chain domain and CLU protein functioning remains unclear and requires further studies.

Since previous observations indicated that the urea cycle may have a role in the Alzheimer’s disease (AD) process, we set out to quantify the expression of each gene involved in the urea cycle in control and AD brains and establish whether these genes could be genetic determinants of AD. We first confirmed that all the urea cycle enzyme genes are expressed in the AD brain. The expression of arginase 2 was greater in the AD brain than in the control brain. The presence of the rare arginase 2 allele rs742869 was associated with an increase in the risk of AD in men and with an earlier age at onset for both genders. None of the other genes in the pathway appeared to be differentially expressed in the AD brain or act as genetic determinants of the disease.

The only established genetic determinant of non-Mendelian forms of Alzheimer’s disease (AD) is the ε4 allele of the apolipoprotein E gene (APOE). Recently, it has been reported that the P86L polymorphism of the calcium homeostasis modulator 1 gene (CALHM1) is associated with the risk of developing AD. In order to independently assess this association, we performed a meta-analysis of 7,873 AD cases and 13,274 controls of Caucasian origin (from a total of 24 centres in Belgium, Finland, France, Italy, Spain, Sweden, the UK and the USA). Our results indicate that the CALHM1 P86L polymorphism is likely not a genetic determinant of AD but may modulate age at onset by interacting with the effect of the ε4 allele of the APOE gene.

Summary

The microtubule associated protein Tau is mainly expressed in neurons of the central nervous system and is crucial in axonal maintenance and axonal transport. The rationale for Tau as a biomarker of neurodegenerative diseases is that it is a major component of abnormal intraneuronal aggregates observed in numerous of these diseases named Tauopathies, including Alzheimer’s disease. The molecular diversity of Tau is very useful when analysing it in the brain or in the peripheral fluids. Immunohistochemical and biochemical characterisation of Tau aggregates in the brain allows the post-mortem classification and differential diagnosis of Tauopathies. As peripheral biomarker of Alzheimer’s disease in the cerebrospinal fluid, Tau proteins are now validated for diagnosis and predictive purposes. For the future, the detailed characterization of Tau in brain and in peripheral fluids will lead to novel promising biomarkers for differential diagnosis of dementia and monitoring of therapeutics.

During normal megakaryocyte development, in response to thrombopoetin, mature cells enter a senescence-like state in which they shed platelets; this state, characterized by cell cycle arrest, is defective in malignant megakaryocytes.

Thrombopoietin (TPO) via signaling through its cognate receptor MPL is a key cytokine involved in the regulation of megakaryocyte differentiation leading to platelet production. Mature megakaryocytes are polyploid cells that have arrested DNA replication and cellular proliferation but continue sustained protein synthesis. Here, we show that TPO induces cell-cycle arrest in the megakaryocytic UT7-MPL cell line by the activation of the ERK/MAPK pathway, induction of p21CIP transcription, and senescence markers through EGR1 activation. A similar senescence-like process was also detected in normal primary postmitotic megakaryocytes. In contrast, senescence was not observed in malignant megakaryocytes derived from primary myelofibrosis patients (a form of chronic myeloid hemopathy). Our data indicate that polyploid mature megakaryocytes receive signals from TPO to arrest cell proliferation and enter a senescent-like state. An escape from this physiological process may be associated with certain myeloproliferative neoplasms leading to abnormal megakaryocytic proliferation.

Author Summary

Megakaryocytes are huge bone marrow cells that shed platelets into the blood stream to promote clotting at sites of injury. Mature megakaryocytes differentiate from precursor cells in response to a hormone called thrombopoetin. Here, we show that as part of this normal differentiation process mature megakaryocytes enter a state called senescence in which cell division stops—a feature normally associated with cell aging and death. By studying megakaryocytes in culture, we were able to determine the biochemical pathway induced by thrombopoetin that leads to gene activation associated with senescence. We conclude that thrombopoietin acts differently at two steps in megakaryocyte differentiation: in the early stages it induces megakaryocyte proliferation, and at a latter stage it arrests the cell division cycle leading to platelet production by these cells. Interestingly, certain malignant megakaryocytes did not undergo senescence in response to thrombopoetin, which might explain the abnormal proliferation of these cancerous cells.

Objective

To examine the association between use of medications with anticholinergic properties, cognitive decline and incident dementia in a large community-based sample of subjects aged 65 years and over.

Methods

Participants were 4128 women and 2784 men from a population-based cohort recruited from three French cities. Cognitive performance, clinical diagnosis of dementia and anticholinergic use were evaluated at base-line, 2 and 4 year later.

Results

7.5% of subjects reported anticholinergic drug use at base-line. Multivariate adjusted logistic regression indicated that women reporting anticholinergic drugs at base-line showed greater decline over four years in verbal fluency scores (OR=1.41, CI=1.11–1.79) and in global cognitive functioning (OR=1.22, CI=0.96–1.55) than women not using anticholinergic drugs. In men, an association was found with decline in visual memory (OR=1.63, CI=1.08–2.47) and to a lesser extent in executive function (OR=1.47, CI=0.89–2.44). Significant interactions were observed in women between anticholinergic use and age, apolipoprotein E, or hormone replacement therapy. A significantly 1.4–2 fold higher risk of cognitive decline was observed for continuous anticholinergic users but not for those having discontinued. The risk of incident dementia over the four-year followup was also increased in continuous users (HR=1.65, CI=1.00–2.73) but not in those having discontinued anticholinergic drugs (HR=1.28, CI=0.59–2.76).

Conclusions

Elderly people taking anticholinergic drugs were at increased risk for cognitive decline and dementia. Discontinuing anticholinergic treatment was associated with a decreased risk. Physicians should carefully consider prescription of anticholinergic drugs in elderly people especially in the oldest old and persons at high genetic risk of cognitive disorder.

Background

Subclinical vascular or degenerative lesions occur in the brain before the clinical expression of dementia. Those lesions in a brain that just experienced a stroke may have lower thresholds for early epileptic seizures. Therefore, epileptic seizures may be a marker of subclinical brain lesions, which may lead to dementia.

Objective

To test the hypothesis that patients with stroke who have epileptic seizures without dementia have an increased risk of new‐onset dementia.

Methods

169 consecutive patients with stroke without pre‐existing dementia recruited in the Lille Stroke/Dementia Study were investigated (90 men; 150 ischaemic strokes; median age 73 years). Pre‐stroke cognitive functions were evaluated with the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE), with a cut‐off of 104 for the diagnosis of dementia. The patients were followed up over a 3‐year period. Dementia was diagnosed with International Classification of Diseases, 10th revision criteria in survivors who underwent neurological visits, and with the IQCODE score in those who could not. The relationship between epileptic seizures and new‐onset dementia was studied within 3 years, using life‐table methods.

Results

9 patients (5.3%; 95% CI 2.9 to 8.7%) had early seizures. Epileptic seizures were independent predictors of new‐onset dementia within 3 years after stroke (HR 3.81; 95% CI 1.13 to 12.82), with increasing age (HR 1.04; 95% CI 1.01 to 1.08), IQCODE scores at admission (HR 1.08; 95% CI 1.02 to 1.13) and diabetes mellitus (HR 3.52; 95% CI 1.46 to 8.47).

Conclusion

Patients with stroke who have epileptic seizures may be at increased risk of dementia. Whether cognitive follow‐up should be systematically performed in those patients remains to be validated.

SUMMARY

Alzheimer’s disease (AD) is a genetically heterogeneous disorder characterized by early hippocampal atrophy and cerebral Aβ peptide deposition. Using TissueInfo to screen for genes preferentially expressed in the hippocampus and located in AD linkage regions, we identified a novel gene on 10q24.33 that we call CALHM1. We show that CALHM1 encodes a multipass transmembrane glycoprotein that controls cytosolic Ca2+ concentrations and Aβ levels. CALHM1 homomultimerizes, shares strong sequence similarities with the selectivity filter of the NMDA receptor, and generates a large Ca2+ conductance across the plasma membrane. Importantly, we determined that the CALHM1 P86L polymorphism (rs2986017) is significantly associated with AD in independent case-control studies of 3,404 participants (allele-specific OR=1.44, P=2×10−10). We further found that the P86L polymorphism increases Aβ levels by interfering with CALHM1-mediated Ca2+ permeability. We propose that CALHM1 encodes an essential component of a novel cerebral Ca2+ channel that controls Aβ levels and susceptibility to AD.