The apolipoprotein E epsilon4 allele is not a significant risk factor for frontotemporal dementia

Glial cells and adaptive immunity in frontotemporal dementia with tau pathology

Neuroinflammation is involved in the aetiology of many neurodegenerative disorders including Alzheimer's disease, Parkinson's disease and motor neuron disease. Whether neuroinflammation also plays an important role in the pathophysiology of frontotemporal dementia is less well known. Frontotemporal dementia is a heterogeneous classification that covers many subtypes, with the main pathology known as frontotemporal lobar degeneration. The disease can be categorized with respect to the identity of the protein that causes the frontotemporal lobar degeneration in the brain. The most common subgroup describes diseases caused by frontotemporal lobar degeneration associated with tau aggregation, also known as primary tauopathies. Evidence suggests that neuroinflammation may play a role in primary tauopathies with genome-wide association studies finding enrichment of genetic variants associated with specific inflammation-related gene loci. These loci are related to both the innate immune system, including brain resident microglia, and the adaptive immune system through possible peripheral T-cell involvement. This review discusses the genetic evidence and relates it to findings in animal models expressing pathogenic tau as well as to post-mortem and PET studies in human disease. Across experimental paradigms, there seems to be a consensus regarding the involvement of innate immunity in primary tauopathies, with increased microglia and astrocyte density and/or activation, as well as increases in pro-inflammatory markers. Whilst it is less clear as to whether inflammation precedes tau aggregation or vice versa; there is strong evidence to support a microglial contribution to the propagation of hyperphosphorylated in tau frontotemporal lobar degeneration associated with tau aggregation. Experimental evidence-albeit limited-also corroborates genetic data pointing to the involvement of cellular adaptive immunity in primary tauopathies. However, it is still unclear whether brain recruitment of peripheral immune cells is an aberrant result of pathological changes or a physiological aspect of the neuroinflammatory response to the tau pathology.

Plasma cholesterol in Alzheimer's disease and frontotemporal dementia

Background

The relationship between the apolipoprotein E (APOE)-ε4 allele, triglyceride (TG) level, and cholesterol level and an increased risk of developing Alzheimer's disease (AD) has been well established, but their relationship with behavioral-variant frontotemporal dementia (bvFTD) is not well-known.

Methodology

The levels of TGs, total cholesterol (TC), low-density lipoprotein (LDL), and high-density lipoprotein were measured in bvFTD and AD patients and in normal controls (NCs). DNA was extracted, and APOE was genotyped.

Results

The APOE-ε4 allele frequency was higher in the AD group than in the NC group, but no difference was found between the AD and the bvFTD groups. The bvFTD group had higher LDL than the AD group, and significant differences were also found for the cholesterol level in the dementia groups compared with the NC group. Elevated LDL level was positively correlated with appetite and eating score in the bvFTD group. Compared with the AD patients and NCs without the APOE-ε4 allele, those with the APOE-ε4 allele had higher TC, but its correlation with the bvFTD group was absent.

Conclusions

The bvFTD and the AD groups had higher cholesterol levels. The APOE-ε4 allele and eating behavior might modify lipid metabolism in dementia. TG and cholesterol analyses may offer a new opportunity for targeted treatments.

Impact of Apolipoprotein E gene polymorphism during normal and pathological conditions of the brain across the lifespan

The central nervous system (CNS) is the cellular substrate for the integration of complex, dynamic, constant, and simultaneous interactions among endogenous and exogenous stimuli across the entire human lifespan. Numerous studies on aging-related brain diseases show that some genes identified as risk factors for some of the most common neurodegenerative diseases - such as the allele 4 of APOE gene (APOE4) for Alzheimer's disease (AD) - have a much earlier neuro-anatomical and neuro-physiological impact. The impact of APOE polymorphism appears in fact to start as early as youth and early-adult life. Intriguingly, though, those same genes associated with aging-related brain diseases seem to influence different aspects of the brain functioning much earlier actually, that is, even from the neonatal periods and earlier. The APOE4, an allele classically associated with later-life neurodegenerative disorders as AD, seems in fact to exert a series of very early effects on phenomena of neuroplasticity and synaptogenesis that begin from the earliest periods of life such as the fetal ones.We reviewed some of the findings supporting the hypothesis that APOE polymorphism is an early modifier of various neurobiological aspects across the entire human lifespan - from the in-utero to the centenarian life - during both normal and pathological conditions of the brain.

Genetic Variation in the Ontario Neurodegenerative Disease Research Initiative

Background/Objective:

Apolipoprotein E (APOE) E4 is the main genetic risk factor for Alzheimer’s disease (AD). Due to the consistent association, there is interest as to whether E4 influences the risk of other neurodegenerative diseases. Further, there is a constant search for other genetic biomarkers contributing to these phenotypes, such as microtubule-associated protein tau (MAPT) haplotypes. Here, participants from the Ontario Neurodegenerative Disease Research Initiative were genotyped to investigate whether the APOE E4 allele or MAPT H1 haplotype are associated with five neurodegenerative diseases: (1) AD and mild cognitive impairment (MCI), (2) amyotrophic lateral sclerosis, (3) frontotemporal dementia (FTD), (4) Parkinson’s disease, and (5) vascular cognitive impairment.

Methods:

Genotypes were defined for their respective APOE allele and MAPT haplotype calls for each participant, and logistic regression analyses were performed to identify the associations with the presentations of neurodegenerative diseases.

Results:

Our work confirmed the association of the E4 allele with a dose-dependent increased presentation of AD, and an association between the E4 allele alone and MCI; however, the other four diseases were not associated with E4. Further, the APOE E2 allele was associated with decreased presentation of both AD and MCI. No associations were identified between MAPT haplotype and the neurodegenerative disease cohorts; but following subtyping of the FTD cohort, the H1 haplotype was significantly associated with progressive supranuclear palsy.

Conclusion:

This is the first study to concurrently analyze the association of APOE isoforms and MAPT haplotypes with five neurodegenerative diseases using consistent enrollment criteria and broad phenotypic analysis.

Updated meta-analysis of the role of APOE ε2/ε3/ε4 alleles in frontotemporal lobar degeneration

We performed an updated meta-analysis to assess the role of the ε2/ε3/ε4 alleles of Apolipoprotein E gene (APOE) in frontotemporal lobar degeneration (FTLD). The relevant articles were retrieved from PubMed, CENTRAL, EMBASE and Web of Science databases, and 51 eligible case-control studies with 5123 cases and 20566 controls were selected after screening according to inclusion and exclusion criteria. Our analysis demonstrated that APOE ε4 was associated with increased FTLD risk in all genetic models (ε4 vs. ε3 allele, ε4 vs. ε2 allele, ε4 vs. ε2+ε3+ε4 allele, ε4 vs. ε2+ε3+ε4 carrier, ε4ε4 vs. ε3ε3, ε3ε4 vs. ε3ε3, ε3ε4+ε4ε4 vs. ε3ε3, ε4ε4 vs. ε3ε3+ε3ε4, all P < 0.01, odds ratio [OR] > 1). Subgroup analysis revealed significant association between APOE ε4 and FTLD (P < 0.01, OR > 1) for the Caucasian, Italian, population based (PB), P > 0.05 value of the Hardy-Weinberg Equilibrium (HWE), Newcastle-Ottawa scale score > 6, and behavioral variant frontotemporal dementia (bvFTD) subgroups. However, there was no significant association between the APOE ε2 allele and FTLD (P > 0.05) in most genetic models and sub-group analyses. Begg's and Egger's tests also revealed no publication bias, and sensitivity analysis showed that our data analysis was robust. Thus our meta-analyses suggest that APOE ε4 is a genetic risk factor in patients with FTLD.

Frontotemporal dementia

Frontotemporal dementia (FTD) is a neurodegenerative disorder characterized by progressive changes in behavior, personality, and language with involvement of the frontal and temporal regions of the brain. About 40% of FTD cases have a positive family history, and about 10% of these cases are inherited in an autosomal-dominant pattern. These gene defects present with distinct clinical phenotypes. As the diagnosis of FTD becomes more recognizable, it will become increasingly important to keep these gene mutations in mind. In this chapter, we review the genes with known associations to FTD. We discuss protein functions, mutation frequencies, clinical phenotypes, imaging characteristics, and pathology associated with these genes.

Genetic architecture of sporadic frontotemporal dementia and overlap with Alzheimer's and Parkinson's diseases

BACKGROUND

Clinical, pathological and genetic overlap between sporadic frontotemporal dementia (FTD), Alzheimer's disease (AD) and Parkinson's disease (PD) has been suggested; however, the relationship between these disorders is still not well understood. Here we evaluated genetic overlap between FTD, AD and PD to assess shared pathobiology and identify novel genetic variants associated with increased risk for FTD.

METHODS

Summary statistics were obtained from the International FTD Genomics Consortium, International PD Genetics Consortium and International Genomics of AD Project (n>75 000 cases and controls). We used conjunction false discovery rate (FDR) to evaluate genetic pleiotropy and conditional FDR to identify novel FTD-associated SNPs. Relevant variants were further evaluated for expression quantitative loci.

RESULTS

We observed SNPs within the HLA, MAPT and APOE regions jointly contributing to increased risk for FTD and AD or PD. By conditioning on polymorphisms associated with PD and AD, we found 11 loci associated with increased risk for FTD. Meta-analysis across two independent FTD cohorts revealed a genome-wide signal within the APOE region (rs6857, 3'-UTR=PVRL2, p=2.21×10^-12), and a suggestive signal for rs1358071 within the MAPT region (intronic=CRHR1, p=4.91×10^-7) with the effect allele tagging the H1 haplotype. Pleiotropic SNPs at the HLA and MAPT loci associated with expression changes in cis-genes supporting involvement of intracellular vesicular trafficking, immune response and endo/lysosomal processes.

CONCLUSIONS

Our findings demonstrate genetic pleiotropy in these neurodegenerative diseases and indicate that sporadic FTD is a polygenic disorder where multiple pleiotropic loci with small effects contribute to increased disease risk.

Associations between APOE polymorphisms and seven diseases with cognitive impairment including Alzheimer's disease, frontotemporal dementia, and dementia with Lewy bodies in southeast China

Supplemental Digital Content is available in the text.

Objective

To explore the effect of APOE polymorphisms on patients with cognitive impairments in The Chinese Han population.

Materials and methods

A total of 1027 cases with Alzheimer’s disease (AD), 40 cases with vascular dementia (VaD), 28 cases with behavioral variant frontotemporal dementia (bvFTD), 54 cases with semantic dementia (SD), 44 cases with dementia with Lewy bodies (DLB), 583 cases with mild cognitive impairment (MCI), and 32 cases with vascular cognitive impairment no dementia (VCIND) were recruited consecutively from memory disorders clinics in Huashan Hospital between January 2010 and December 2014. The 1149 cognitively normal controls were recruited from the community epidemiologic investigations. The APOE genotypes were determined using the TaqMan assay.

Results

The distribution of genotype and allele frequencies of APOE differed significantly between control and AD or MCI, with ε4 increasing the risk of AD and MCI in a dose-dependent pattern and ε2 decreasing the risk of AD, but not the risk of MCI. As for VaD, significant differences in the APOE genotype distribution were found compared with the controls. E4/4 increased the risk of VaD and ε4 increased the risk of VCIND in women. The allele distribution differed between bvFTD and controls, but genotype and allele frequencies of APOE did not affect the risk of bvFTD, SD, and DLB.

Conclusion

In The Chinese Han population, APOE ε4 increased the risk of AD and MCI in a dose-dependent manner and ε2 decreased the risk of AD as reported previously. APOEε4 might increase risk in VaD and female patients with VCIND, but no effects of APOE on bvFTD, DLB, and SD were found.

Clinical characteristics of parkinsonism in frontotemporal dementia according to subtypes

BACKGROUND

We investigated the prevalence of parkinsonism in frontotemporal dementia (FTD) subtypes and the cognitive and behavioral differences between FTD with and without parkinsonism in a well-structured, prospective cohort.

METHODS

One hundred and ninety-one FTD patients were enrolled and all patients underwent comprehensive neurological evaluations, neuropsychological tests, and the Unified Parkinson's Disease Rating Scale.

RESULTS

The prevalence of parkinsonism was 38.7% (74 patients), and included 33 (46.5%) behavioral variant FTD (bvFTD), 16 (24.2%) semantic dementia (SD), 19 (45.2%) progressive nonfluent aphasia (PNFA), and 6 (50%) FTD associated with motor neuron disease (FTD-MND). SD patients with parkinsonism had higher CDR sum of boxes scores (9.7±4.5 vs 6.2±4.5, p=0.024), frontal behavioral inventory total score (33.7±20.5 vs 24.3±14.5, p=0.045), and executive function score of frontal executive dysfunction, disinhibition, and apathy (28.9±13.7 vs 19.2±12.9, p=0.021) than those without parkinsonism. Seoul Instrumental Activities of Daily Living score (bvFTD: 23.5±11.7 vs 17.3±11.3, p=0.031, SD: 23.1±11.1 vs 11.3±9.3, p=0.005) was higher for bvFTD and SD with parkinsonism than for those without parkinsonism.

CONCLUSIONS

Parkinsonism is found to be more common in patients with bvFTD, PNFA, and FTD-MND patients than those with SD. Behavioral disturbances were more prominent in SD with parkinsonism than without. Additional studies are needed to determine the pathomechanism and optimal treatment of parkinsonism in different FTD subtypes.

Gene promoter methylation and expression of Pin1 differ between patients with frontotemporal dementia and Alzheimer's disease

Frontotemporal Dementia (FTD) and Alzheimer's Disease (AD) share the accumulation of fibrillar aggregates of misfolded proteins. To better understand these neurodegenerative diseases and identify biomarkers in easily accessible cells, we investigated DNA methylation at Pin1 gene promoter and its expression in peripheral blood mononuclear cells of FTD patients. We found a lower gene expression of Pin1 with a higher DNA methylation in three CpG sites at Pin1 gene promoter analysed in FTD subjects, in contrast to a higher gene expression with a lower methylation in AD subjects and controls. These data suggest an important and distinct involvement of Pin1 in these two types of dementia.

Frontotemporal dementia and primary progressive aphasia, a review

Frontotemporal dementias are neurodegenerative diseases in which symptoms of frontal and/or temporal lobe disease are the first signs of the illness, and as the diseases progress, they resemble a focal left hemisphere process such as stroke or traumatic brain injury, even more than a neurodegenerative disease. Over time, some patients develop a more generalized dementia. Four clinical subtypes characterize the predominant presentations of this illness: behavioral or frontal variant FTD, progressive nonfluent aphasia, semantic dementia, and logopenic primary progressive aphasia. These clinical variants correlate with regional patterns of atrophy on brain imaging studies such as MRI and PET scanning, as well as with biochemical and molecular genetic variants of the disorder. The treatment is as yet only symptomatic, but advances in molecular genetics promise new therapies.

Molecular Dissection of Cyclosporin A's Neuroprotective Effect Reveals Potential Therapeutics for Ischemic Brain Injury

After the onset of brain ischemia, a series of events leads ultimately to the death of neurons. Many molecules can be pharmacologically targeted to protect neurons during these events, which include glutamate release, glutamate receptor activation, excitotoxicity, Ca²⁺ influx into cells, mitochondrial dysfunction, activation of intracellular enzymes, free radical production, nitric oxide production, and inflammation. There have been a number of attempts to develop neuroprotectants for brain ischemia, but many of these attempts have failed. It was reported that cyclosporin A (CsA) dramatically ameliorates neuronal cell damage during ischemia. Some researchers consider ischemic cell death as a unique process that is distinct from both apoptosis and necrosis, and suggested that mitochondrial dysfunction and Δψ collapse are key steps for ischemic cell death. It was also suggested that CsA has a unique neuroprotective effect that is related to mitochondrial dysfunction. Here, I will exhibit examples of neuroprotectants that are now being developed or in clinical trials, and will discuss previous researches about the mechanism underlying the unique CsA action. I will then introduce the results of our cDNA subtraction experiment with or without CsA administration in the rat brain, along with our hypothesis about the mechanism underlying CsA’s effect on transcriptional regulation.

Toward the treatment and prevention of Alzheimer's disease: rational strategies and recent progress

Alzheimer's disease (AD) is the major cause of late-life brain failure. In the past 25 years, autosomal dominant forms of AD were found to be primariy attributable to mutations in one of two presenilins, polytopic proteins that contain the catalytic site of the γ-secretase protease that releases the amyloid beta (Aβ) peptide. Some familial AD is also due to mutations in the amyloid precursor protein (APP), but recently a mutation in APP was discovered that reduces Aβ generation and is protective against AD, further implicating amyloid metabolism. Prion-like seeding of amyloid fibrils and neurofibrillary tangles has been invoked to explain the stereotypical spread of AD within the brain. Treatment trials with anti-Aβ antibodies have shown target engagement, if not significant treatment effects. Attention is increasingly focused on presymptomatic intervention, because Aβ mismetabolism begins up to 25 years before symptoms begin. AD trials deriving from new biological information involve extraordinary international collaboration and may hold the best hope for success in the fight against AD.

Apolipoprotein E polymorphisms in frontotemporal lobar degeneration: a meta-analysis

OBJECTIVE

Case-control studies have not been consistent in showing association between apolipoprotein E (APOE) polymorphisms and frontotemporal lobar degeneration (FTLD), producing contradictory findings. The study objective was to define and quantify further the disease risk associated with the carriage of different APOE alleles to determine whether APOE gene polymorphism is a risk factor for FTLD.

METHODS

A systematic review of all case-control studies investigating the association between the APOE gene and FTLD up to December 2011 was conducted. Case-control studies using clinical or pathological criteria for FTLD and reporting APOE allelic or genotypic data were included. Pooled odds ratios (ORs) were estimated using a random effects model, and 95% confidence intervals (CIs) were calculated.

RESULTS

Twenty-eight case-control studies met the inclusion criteria. Carriage of the ε2 allele had no effect on disease risk. On the contrary, carriage of the ε4 allele was associated with a significantly increased disease risk (ε4 carriers vs non-ε4 carriers: OR, 1.94; 95% CI, 1.43-2.64; ε4 vs ε3 allele: OR, 1.83; 95% CI, 1.34-2.52). Furthermore, a gene-dosage effect for the ε4 allele was found. There was no evidence of publication bias, but heterogeneity between the studies was high.

CONCLUSIONS

Our study provides evidence for an association between the APOE ε4 allele and frontotemporal lobar degeneration.

Apolipoprotein Ε ε4 frequency is increased among Chinese patients with frontotemporal dementia and Alzheimer's disease

The relationship between the apolipoprotein E (ApoE) ε4 genotype and an increased risk of developing Alzheimer's disease (AD) has been well established in Caucasians but is less established among other ethnicities. ApoE ε4 has also been associated with several other neurological disorders. Whether ApoΕ4 ε4 is a risk factor for frontotemporal dementia (FTD) remains controversial. This study examined 432 patients with AD, 62 with FTD, and 381 sex- and age-matched controls. The ApoE ε4 allele frequency was significantly increased among patients in the AD and FTD groups compared with controls. The frequency of the ApoΕ ε4 allele was 24.86% in late-onset AD (p < 0.01), 18.02% in early-onset AD (p < 0.01), 16.13% in FTD (p < 0.01), and 7.34% in controls. ApoΕ ε4 prevalence was similar in the FTD and AD groups. The present study suggests that the ApoE ε4 allele is a risk factor for both disorders.

Frontotemporal lobar degeneration: current knowledge and future challenges

Frontotemporal lobar degeneration (FTLD) is one of the most frequent neurodegenerative disorders with a presenile onset. It presents with a spectrum of clinical manifestations, ranging from behavioral and executive impairment to language disorders and motor dysfunction. New diagnostic criteria identified two main cognitive syndromes: behavioral variant frontotemporal dementia (bvFTD) and primary progressive aphasia. Regarding bvFTD, new criteria include the use of biomarkers. According to them, bvFTD can be classified in "possible" (clinical features only), "probable" (inclusion of imaging biomarkers) and "definite" (in the presence of a known causal mutation or at autopsy). Familial aggregation is frequently reported in FTLD, and about 10 % of cases have an autosomal dominant transmission. Microtubule-associated protein tau gene mutations have been the first ones identified, and are generally associated with early onset (40-50 years) and with the bvFTD phenotype. More recently, progranulin gene mutations were recognized in association with the familial form of FTLD and a hexanucleotide repetition in C9ORF72 has been shown to be responsible for familial FTLD and amyotrophic lateral sclerosis. In addition, other genes are linked to rare cases of familiar FTLD. Lastly, a number of genetic risk factors for sporadic forms have also been identified.

Genetics of frontotemporal lobar degeneration

Frontotemporal lobar degeneration (FTLD), the most frequent neurodegenerative disorder with a presenile onset, presents with a spectrum of clinical manifestations, ranging from behavioral and executive impairment to language disorders and motor dysfunction. Familial aggregation is frequently reported, and about 10% of cases have an autosomal dominant transmission. Microtubule associated protein tau (MAPT) gene mutations have been the first ones identified and are associated with early onset behavioral variant frontotemporal dementia phenotype. More recently, progranulin gene (GRN) mutations were recognized in association with familial form of FTLD. In addition, other genes are linked to rare cases of familial FTLD. Lastly, a number of genetic risk factors for sporadic forms have also been identified. In this review, current knowledge about mutations at the basis of familial FTLD will be described, together with genetic risk factors influencing the susceptibility to FTLD.

Behavioral genetics of neurodegenerative disorders

Alzheimer's disease (AD) is the most common cause of dementia in the elderly, and is typically characterized by memory loss. In addition, during the disease progression, most patients develop behavioural and psychiatric symptoms of dementia (BPSD). Frontotemporal Lobar Degeneration (FTLD) is the most frequent neurodegenerative disorder with a presenile onset. It is characterized mainly by behavioural disturbances, whereas memory is conserved. The two major neuropathologic hallmarks of AD are extracellular Amyloid beta (Ab) plaques and intracellular neurofibrillary tangles (NFTs). Conversely, in FTLD the deposition of tau has been observed in a number of cases, but in several brains there is no deposition of tau but instead a positivity for ubiquitin. In some families these diseases are inherited in an autosomal dominant fashion. Genes responsible for familial AD include the Amyloid Precursor Protein (b-APP), Presenilin 1 (PS1)and Presenilin 2 (PS2). The majority of mutations in these genes are often associated with a very early onset (40–50 years of age). Regarding FTLD, the first mutations described are located in the Microtubule Associated Protein Tau gene(MAPT). Tau is a component of microtubules, which represent the internal support structures for the transport of nutrients, vesicles, mitochondria and chromosomes within the cell. Mutations in MAPT are associated with an early onset of the disease (40–50 years), and the clinical phenotype is consistent with Frontotemporal Dementia (FTD). Recently, mutations in a second gene, named progranulin(GRN), have been identified in some families with FTLD. The pathology associated with these mutations is most frequently characterized by the immunostaining of TAR DNA Binding Protein 43 (TDP-43), which is a transcription factor. The clinical phenotype associated with GRN mutations is highly heterogeneous,including FTD, Progressive Aphasia, Corticobasal Syndrome, and AD. Age at disease onset is variable, ranging from 45 to 85 years of age. The majority of cases of AD and FTLD are however sporadic, and likely several genetic and environmental factors contribute to their development. Concerning AD, it is known that the presence of the e4 allele of the Apolipoprotein E gene is a susceptibility factor,increasing the risk of about 4 fold. A number of additional genetic factors,including cytokines, chemokines, Nitric Oxide Synthases, contribute to the susceptibility for the disease. Some of them also influence the risk to develop FTLD.Variability in serotonin transporter gene could influence the development of BPSD. In this chapter, current knowledge on molecular mechanisms at the basis of AD and FTLD, as well as the role of genetics, will be presented and discussed.

Alterations in metabolism-related genes induced in SHSY5Y cells by okadaic acid exposure

Okadaic acid (OA) is a widely distributed marine toxin produced by several phytoplanktonic species and responsible for diarrheic shellfish poisoning in humans. At the molecular level OA is a specific inhibitor of several types of serine/threonine protein phosphatases. Due to this enzymic inhibition, OA was reported to induce numerous alterations in relevant cellular physiological processes, including several metabolic pathways such as glucose uptake, lipolysis and glycolysis, heme metabolism, and glycogen and protein synthesis. In order to further understand the underlying mechanisms involved in OA-induced effects on cellular metabolism, the expression levels of six genes related to different catabolic and anabolic metabolism-related processes were analyzed by real-time polymerase chain reaction. Specifically, the expression patterns of GAPDH, TOMM5, SLC25A4, COII, QARS, and RGS5 genes were determined in SHSY5Y human neuroblastoma cells exposed to OA for 3, 24, or 48 h. All these genes showed alterations in their expression levels after at least one of the OA treatments tested. These alterations provide a basis to understand the mechanisms underlying the previously described OA-induced effects on different metabolic processes, mainly regarding glucose and mitochondrial metabolism. However, other OA-induced affected genes can not be ruled out, and further studies are required to more comprehensively characterize in the mechanisms of OA-induced interaction on cell metabolism.

Review: Recent progress in frontotemporal lobar degeneration

Frontotemporal lobar degeneration (FTLD) is a highly familial condition and is increasingly being recognized as an important form of dementia. The literature published on this disease is often difficult to collate due to the wide range in nomenclature used. Thankfully, consensus recommendations have now been published to address this issue and hopefully the community will adopt these as intended. Much progress has been made in our understanding of the clinical, pathological and genetic understanding of FTLD in recent years. Progranulin and TDP-43 have recently been identified as new important proteins involved in the pathophysiology of FTLD and this latter protein may have potential as a biomarker of this disease. However, much remains before we have a full picture of the genes that cause FTLD and the biological pathways in which they function. The purpose of this review is to summarize the current concepts and recent advances in our knowledge of this disease.

Preliminary evidence that VEGF genetic variability confers susceptibility to frontotemporal lobar degeneration

Frontotemporal lobar degeneration (FTLD) recognizes a strong genetic background, with 30-50% of cases with a positive family history. Despite several efforts to identify monogenic causes of the disease, no clear-cut genetic risk factors for sporadic FTLD are yet known. Recently, increasing evidence points to a pivotal role of vascular endothelial growth factor (VEGF) in the neurodegenerative process, suggesting functions not confined to its originally described vascular effects. The aim of this study was to investigate the role of VEGF as a genetic determinant to FTLD susceptibility. We evaluated a cohort of 274 unrelated Italian patients, including 161 subjects with frontotemporal dementia (FTD), 56 with corticobasal degeneration syndrome, and 57 with progressive supranuclear palsy. Genotype and allele frequencies of four well-known polymorphisms located within the VEGF promoter (-2578C/A, -1190G/A, -1154G/A, and -634G/C) were calculated in patients and in 216 age-matched healthy subjects. Genetic analysis revealed the presence of several significant changes in terms of allele, genotype, and haplotype frequency distributions between patients and controls. Marked differences were observed when the FTD patient subgroup was compared with healthy subjects. Overall, these data provide evidence for the first time that VEGF gene variability represents a susceptibility factor for sporadic FTLD, at least in an Italian population. Future confirmatory studies are mandatory.

Association of GSK3B with Alzheimer disease and frontotemporal dementia

BACKGROUND

Deposits of abnormally hyperphosphorylated tau are a hallmark of several dementias, including Alzheimer disease (AD), and about 10% of familial frontotemporal dementia (FTD) cases are caused by mutations in the tau gene. As a known tau kinase, GSK3B is a promising candidate gene in the remaining cases of FTD and in AD, for which tau mutations have not been found.

OBJECTIVE

To examine the promoter of GSK3B and all 12 exons, including the surrounding intronic sequence, in patients with FTD, patients with AD, and aged healthy subjects to identify single-nucleotide polymorphisms associated with disease.

DESIGN, SETTING, AND PARTICIPANTS

Single-nucleotide polymorphism frequency was examined in a case-control cohort of 48 patients with probable AD, 102 patients with FTD, 38 patients with primary progressive aphasia, and 85 aged healthy subjects. Results were followed up in 2 independent AD family samples consisting of 437 multiplex families with AD (National Institute of Mental Health Genetics Initiative AD Study) or 150 sibships discordant for AD (Consortium on Alzheimer's Genetics Study).

RESULTS

Several rare sequence variants in GSK3B were identified in the case-control study. An intronic polymorphism (IVS2-68G>A) occurred at more than twice the frequency among patients with FTD (10.8%) and patients with AD (14.6%) than in aged healthy subjects (4.1%). The polymorphism showed association with disease in both follow-up samples independently, although only the Consortium on Alzheimer's Genetics sample showed the same direction of association as the case-control sample.

CONCLUSIONS

To our knowledge, this is the first evidence that a gene known to be involved in tau phosphorylation, GSK3B, is associated with risk for primary neurodegenerative dementias. This supports previous work in animal models suggesting that such genes are therapeutic targets.

Pharmacological properties of BN82451: a novel multitargeting neuroprotective agent

BN82451 belongs to a new family of small molecules designated as multitargeting or hybrid molecules. BN82451 is orally active, has good central nervous system penetration, and elicits potent neuronal protection and antiinflammatory properties. Neuronal protection is due to Na+ channel blockade, antioxidant properties, and mitochondria-protecting activity, whereas inhibition of cyclooxygenases is mostly responsible for its antiinflammatory activity. BN82451 has been shown to exert a potent neuroprotective effect in various in vitro and in vivo animal models. BN82451 was found to exert a significant protection in experimental animal models mimicking aspects of cerebral ischemia, Parkinson disease, Huntington disease, and more particularly amyotrophic lateral sclerosis. Collectively, its pharmacological properties designate BN82451 as a promising neuroprotective agent.

Patterns of atrophy differ among specific subtypes of mild cognitive impairment

BACKGROUND

In most patients, mild cognitive impairment (MCI) represents the clinically evident prodromal phase of dementia. This is most well established in amnestic MCI, which is most commonly a precursor to Alzheimer disease (AD). It follows, however, that subjects with MCI who have impairment in nonmemory domains may progress to non-AD degenerative dementias.

OBJECTIVE

To investigate patterns of cerebral atrophy associated with specific subtypes of MCI.

DESIGN

Case-control study.

SETTING

Community-based sample at a tertiary referral center.

PATIENTS

One hundred forty-five subjects with MCI and 145 age- and sex-matched cognitively normal control subjects. Mild cognitive impairment was classified as amnestic, single cognitive domain; amnestic, multiple domain; nonamnestic, single domain; and nonamnestic, multiple domain. Subjects with nonamnestic single-domain MCI were classified into language, attention/executive, and visuospatial subgroups on the basis of specific cognitive impairment.

MAIN OUTCOME MEASURE

Patterns of gray matter loss in the MCI groups compared with control subjects, assessed using voxel-based morphometry.

RESULTS

Subjects in the amnestic single- and multiple-domain groups showed loss in the medial and inferior temporal lobes compared with control subjects, and those in the multiple-domain group also had involvement of the posterior temporal lobe, parietal association cortex, and posterior cingulate. Subjects in the nonamnestic single-domain group with language impairment showed loss in the left anterior inferior temporal lobe. The group with attention/executive deficits showed loss in the basal forebrain and hypothalamus. No coherent patterns of loss were observed in the other subgroups.

CONCLUSIONS

The pattern of atrophy in the amnestic MCI groups is consistent with the concept that MCI in most of these subjects represents prodromal AD. However, the varying patterns in the language and attention/executive subgroups suggest that these subjects may have a different underlying disorder.

The complex aetiology of frontotemporal lobar degeneration

Frontotemporal lobar degeneration (FTLD) is now a widely recognised form of dementia. This heterogeneous disease has been of particular interest to geneticists due to its high rate of heritability with up to 40% of patients reporting a family history of the disease in at least one extra family member. There have been several chromosome loci linked to this disorder and three genes have already been identified. Remarkably, it has been recently demonstrated that 2 of these are only 1.7 Mb from one another on chromosome 17q21, these being tau and progranulin. The identification of these genes has contributed greatly to our understanding of the differing neuropathologies associated with FTLD. Furthermore, the discovery that TDP-43 is a component of the neuronal inclusions seen in the most common neuropathological subtype has also helped expand the biochemical pathways that are the focus of much FTLD research. Nevertheless, other genes causing FTLD remain to be identified and their biology elucidated before we have a complete understanding of the complex aetiology of this disease.

APOE is a potential modifier gene in an autosomal dominant form of frontotemporal dementia (IBMPFD)

PURPOSE

Inclusion-body myopathy, Paget's disease of bone and frontotemporal dementia is an adult-onset autosomal dominant illness (IBMPFD) caused by mutations in the valosin-containing protein (VCP) on chromosome 9p21.1-p12. The penetrance of the gene is 82% for myopathy, 49% for Paget's disease, but may be as low as 30% for frontotemporal dementia. Modifier genes could account for decreased frontotemporal dementia penetrance. In this study apolipoprotein-E (APOE) was evaluated for this role in IBMPFD families based on its known modifier effect in Alzheimer's disease.

METHODS

From a database of 231 members of 15 families, 174 had APOE genotype available for analysis. Logistic regressions on APOE genotype and frontotemporal dementia were performed, using appropriate covariates.

RESULTS AND CONCLUSION

FTD was associated with APOE 4 genotype (P=0.0002), myopathy (P=0.0006), and age (P=0.01), but not microtubule associated protein tau (MAPT) H2 haplotype (P=0.5) or gender (0.09) after adjustment for membership in pedigrees with at least one APOE 4 genotype. These data suggest a potential link between APOE 4 genotype and the specific form of frontotemporal dementia found in IBMPFD. The molecular basis of this link bears further investigation. We did not observe an association of frontotemporal dementia and H2 MAPT haplotype.

Vasectomy in Men With Primary Progressive Aphasia

OBJECTIVE

To study the frequency of vasectomy in men with primary progressive aphasia (PPA).

BACKGROUND

PPA is a dementia syndrome in which aphasia emerges in relative isolation during the initial stages of illness. On the basis of a clinical observation in a patient who dated the onset of symptoms to the period after a vasectomy, and because of the curious sharing of the tau protein exclusively by brain and sperm, vasectomy rates were examined in men with PPA.

METHOD

This study used a case control design. Forty-seven men with PPA and 57 men with no cognitive impairment (NC) between 55 and 80 years of age were surveyed about a history of vasectomy.

RESULTS

The age-adjusted rate of vasectomy in PPA patients (40%) was higher than in NC (16%, P=0.02). There was a younger age at onset for the patients with vasectomy (58.8 vs. 62.9 y, P=0.03).

CONCLUSIONS

Vasectomy may constitute one risk factor for PPA in men. Potential mechanisms mediating risk include vasectomy-induced immune responses to sperm, which shares antigenic epitopes with brain. Antisperm antibodies can also develop in women and become risk factors for PPA.

Functional correlates of Apolipoprotein E genotype in Frontotemporal Lobar Degeneration

Background

It has been recently demonstrated that in Frontotemporal Lobar Degeneration (FTLD) memory deficits at presentation are commoner than previously thought. Apolipoprotein E (ApoE) genotype, the major genetic risk factor in sporadic late-onset Alzheimer Disease (AD), modulates cerebral perfusion in late middle-age cognitively normal subjects. ApoE ε4 homozygous have reduced glucose metabolism in the same regions involved in AD.

The aim of this study was to determine whether ApoE genotype might play a key-role in influencing the cerebral functional pattern as well as the degree of memory deficits in FTLD patients.

Methods

Fifty-two unrelated FTLD patients entered the study and underwent a somatic and neurological evaluation, laboratory examinations, a brain structural imaging study, and a brain functional Single Photon Emission Tomography study. ApoE genotype was determined.

Results

ApoE genotype influenced both clinical and functional features in FTLD. ApoE ε4-carriers were more impaired in long-term memory function (ApoE ε4 vs. ApoE non ε4, 6.3 ± 3.9 vs. 10.1 ± 4.2, p = 0.004) and more hypoperfused in uncus and parahippocampal regions (x,y,z = 38,-6,-20, T = 2.82, cluster size = 100 voxels; -32,-12,-28, T= 2.77, cluster size = 40 voxels).

Conclusion

The present findings support the view that ApoE genotype might be considered a disease-modifying factor in FTLD, thus contributing to define a specific clinical presentation, and might be of relevance for pharmacological approaches.

Apolipoprotein E epsilon4 allele is unrelated to cognitive or functional decline in Alzheimer's disease: retrospective and prospective analysis

OBJECTIVE

The apolipoprotein E (ApoE) epsilon4 allele is a well-documented genetic risk factor for Alzheimer's disease (AD). Its role, if any, in the progression of cognitive and functional impairment in AD has been the subject of discrepant reports in the literature. This study aimed to determine whether ApoE epsilon4 dose is related to the progression of cognitive and functional decline in AD patients by combined retrospective and prospective analyses.

METHODS

A sample of 366 AD patients was genotyped for ApoE. Subjects received tests of cognition (Mini-Mental State Examination, MMSE; Alzheimer's Disease Assessment Scale-Cognitive subscale, ADAS-Cog) and daily function (Instrumental Activities of Daily Living, IADL; Alzheimer's Disease Cooperative Study-Activities of Daily Living, ADCS-ADL) at baseline and at multiple subsequent time points during their participation in a variety of research protocols. In retrospective analyses, scores on baseline cognitive and functional measures were compared cross-sectionally among genotype groups, controlling for duration of symptoms. In prospective analyses, longitudinal rates of change for each measure were computed by linear regression and compared across genotype groups.

RESULTS

No association was observed between ApoE epsilon4 dose and any of the retrospective or prospective measures of cognitive or functional decline in this AD patient sample.

CONCLUSIONS

Although ApoE epsilon4 increases the risk for AD and decreases the age of disease onset in population studies, it did not significantly influence the rate of disease progression in cognitive or functional domains in our sample.

Caspase-dependent alteration of the ADP/ATP translocator triggers the mitochondrial permeability transition which is not required for the low-potassium-dependent apoptosis of cerebellar granule cells

We investigated ADP/ATP exchange mediated by the adenine nucleotide translocator and opening of the mitochondrial permeability transition pore in homogenates from cerebellar granule cells en route to apoptosis induced by low potassium. We showed that, in the first 3 h of apoptosis, when maximum cytochrome c release had already occurred, adenine nucleotide translocator function was impaired owing to the action of reactive oxygen species, but no permeability transition pore opening occurred. Over 3-8 h of apoptosis, the permeability transition pore progressively opened, owing to caspase action, and further ADP/ATP translocator impairment occurred. The kinetics of transport and permeability transition pore opening were inversely correlated, both in the absence and presence of inhibitors of antioxidant and proteolytic systems. We conclude that, en route to apoptosis, alteration of the adenine nucleotide translocator occurs, resulting in permeability transition pore opening. This process depends on the action of caspase on pore component(s) other than the ADP/ATP translocator, because no change in either amount or molecular weight of the latter protein was noted during apoptosis, as measured by western blotting. Cell death occurs via apoptosis in the presence of cyclosporin A, the permeability transition pore inhibitor, thus showing that permeability transition pore opening, not needed for cytochrome c release, is also unnecessary for apoptosis to occur.

The apolipoprotein E epsilon4 allele selectively increases the risk of frontotemporal lobar degeneration in males

OBJECTIVE

To determine whether polymorphic variations in the apolipoprotein E gene (APOE) are associated with increased risk of frontotemporal lobar degeneration (FTLD) when mutation in tau gene is absent.

METHODS

The APOE gene was genotyped by polymerase chain reaction from DNA routinely extracted from blood or brain tissues. The APOE epsilon4 allele frequency in 198 patients with FTLD not associated with mutations in tau gene was compared with that of a control group of 756 normal individuals drawn from the same geographical region. Analyses were done according to clinical subtype or sex.

RESULTS

The APOE epsilon4 allele frequency (19.4%) was increased (p = 0.01) in FTLD v the whole control group (14.1%), while the APOE epsilon2 allele frequency in FTLD (6.5%) was slightly lower than in controls (8.0%) (NS). The APOE epsilon4 allele frequency in men with FTLD (22.3%) was greater (p = 0.002) than in male controls (12.3%); the frequency in women (16.3%) was similar to that in female controls (14.8%) (NS). The APOE epsilon2 allele frequency in men with FTLD was 4.9% while in male controls it was 9.5% (p = 0.06), but there was no difference in women (7.5% v 7.9%, NS). Neither the APOE epsilon2 nor APOE epsilon4 allele frequency varied significantly between any of the clinical subtypes.

CONCLUSIONS

In FTLD not associated with mutations in tau gene, possession of APOE epsilon4 allele in men roughly doubles the chances of developing disease, whereas this has no impact upon disease risk in women.

Frontotemporal dementia—A brief review

Frontotemporal dementia (FTD) is the second most common type of presenile dementia and the forth most common type of senile dementia, but probably the most costly due to its florid symptom characteristics. Clinically, it often presents with changes of personality, restlessness, disinhibition, and impulsiveness and the clinical features can be complicated by neurological signs, such as motor neuron signs, parkinsonism, and gait disturbances. Syndromatically, FTD can be subdivided into a group with predominating behavioural disturbances (frontal variant) and another with predominating language deterioration (temporal variant). Based on the underlying pathological changes, FTD is nosologically divided into disorders such as Pick's disease, frontotemporal lobar degeneration, corticobasal degeneration, progressive supranuclear palsy, and frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17). The cause in sporadic FTD is most often unknown, but in FTDP-17, one of the hereditary FTDs, there is a causative mutation in the tau gene. The frequency of tau-gene mutations is low in sporadic FTD and present in about 10-40% of hereditary FTD. Other types of hereditary FTD have been described, such as FTD caused by mutations in chromosome 3, chromosome 9, and a FTD syndrome can also be caused by mutations in the presenilin-1 gene. Since there is no curative, treatment of prevailing symptoms is the given alternative. Serotonergic acting drugs have been shown to alleviate behavioural symptoms.

Neuropathologic, biochemical, and molecular characterization of the frontotemporal dementias

The frontotemporal dementias (FTDs) are a heterogeneous group of neurodegenerative disorders that are characterized clinically by dementia, personality changes, language impairment, and occasionally extrapyramidal movement disorders. Historically, the diagnosis and classification of FTDs has been fraught with difficulties, especially with regard to establishing a consensus on the neuropathologic diagnosis. Recently, an international group of scientists participated in a consensus conference to develop such neuropathologic criteria. They recommended a diagnostic classification scheme that incorporated a biochemical analysis of the insoluble tau isoform composition, as well as ubiquitin immunohistochemistry. The use and reliability of this classification system has yet to be examined. In this study, we evaluated 21 cases of FTD. Using traditional histochemical stains and tau protein and ubiquitin immunohistochemistry, we separated each case into one of the following categories: classic Pick disease (PiD; n = 7), corticobasal degeneration (CBD; n = 5), dementia lacking distinctive histopathologic features (DLDH; n = 4), progressive supranuclear palsy (PSP; n = 2), frontotemporal lobar degeneration with motor neuron disease or motor neuron disease-type inclusions (FTLD-MND/MNI; n = 2), and neurofibrillary tangle dementia (NFTD; n = 1). Additionally, we independently categorized each case by the insoluble tau isoform pattern, including 3R (n = 5), 4R (n = 7), 3R/4R (n = 3), and no insoluble tau (n = 6). As suggested by the proposed diagnostic scheme, we found that the insoluble tau isoform patterns correlated strongly with the independently derived histopathologic diagnoses (p < 0.001). The data show that cases containing predominantly 3R tau were classic PiD (100%). Cases with predominantly 4R tau were either CBD (71%) or PSP (29%). Cases with both 3R and 4R tau were either a combination of PiD and Alzheimer disease (67%) or NFTD (33%). Finally, cases with no insoluble tau were either DLDH (67%) or FTLD-MND/MNI (33%). To further characterize these cases, we also performed quantitative Western blots for soluble tau, APOE genotyping, and, in selected cases, tau gene sequencing. We show that soluble tau is reduced in DLDH and FTLD-MND/MNI and that APOE4 is overrepresented in PiD and DLDH. We also identified a new family with the R406W mutation and pathology consistent with NFTD. This study validates the recently proposed diagnostic criteria and forms a framework for further refinement of this classification scheme.

Distribution of apolipoprotein E alleles in the Omani population

OBJECTIVE

To estimate the apolipoprotein E (apo E) allele distribution in the Omani population and to compare them with those of other populations.

SUBJECTS AND METHODS

One hundred and sixty-two healthy Omanis of Arab Bedouin origin were genotyped by polymerase chain reaction followed by restriction fragment length polymorphism.

RESULTS

The apo E allele frequencies were: epsilon2, 0.052; epsilon3, 0.886; epsilon4, 0.062. This pattern of distribution, characterized by the lowest epsilon4 and among the highest epsilon3 allele frequencies in the world, was very similar to that of Arabs, Southern Europeans of the Mediterranean basin, Indians, and Japanese populations.

CONCLUSION

The results indicate that the allelic distribution of apo E in healthy Omanis is characterized by low Apo epsilon4 and high epsilon3 allele frequencies similar to those of other Arab, Southern European, Japanese and Indian populations. The homogeneous distribution of apo E alleles in this group of populations might have been influenced by diet and/or genetic admixture.

APOE and modulation of Alzheimer's and frontotemporal dementia

To investigate the difference in the morphologic expression of frontotemporal dementia (FTD) and Alzheimer's disease (AD) in patients carrying and not carrying the epsilon4 allele of APOE, MR images of 26 controls, 18 AD patients (11 carrying the epsilon4 allele, seven non-carriers), and eight FTD (two carriers, six non-carriers) were compared using voxel by voxel analysis. Greater atrophy was found in the disease-specific regions of the epsilon4 carriers vs the non-carriers at P < 0.05 corrected: medial temporal atrophy was greater in the AD carrying the epsilon4 allele, right ventral striatal atrophy in the FTD carrying the allele. The non-carriers did not have atrophic regions compared to the carriers. The epsilon4 allele of the APOE might modulate the expression of degenerative dementias by enhancing the specific effects of neurodegenerative diseases on the brain.

The role of tau (MAPT) in frontotemporal dementia and related tauopathies

Tau is a multifunctional protein that was originally identified as a microtubule-associated protein. In patients diagnosed with frontotemporal dementia and parkinsonism linked to chromosome 17, mutations in the gene encoding tau (MAPT) have been identified that disrupt the normal binding of tau to tubulin resulting in pathological deposits of hyperphosphorylated tau. Abnormal filamentous tau deposits have been reported as a pathological characteristic in several other neurodegenerative diseases, including frontotemporal dementia, Pick Disease, Alzheimer disease, argyrophilic grain disease, progressive supranuclear palsy, and corticobasal degeneration. In the last five years, extensive research has identified 34 different pathogenic MAPT mutations in 101 families worldwide. In vitro, cell-free and transfected cell studies have provided valuable information on tau dysfunction and transgenic mice carrying human MAPT mutations are being generated to study the influence of MAPT mutations in vivo. This mutation update describes the considerable differences in clinical and pathological presentation of patients with MAPT mutations and summarizes the effect of the different mutations on tau functioning. In addition, the role of tau as a genetic susceptibility factor is discussed, together with the genetic evidence for additional causal genes for tau-positive as well as tau-negative dementia.

Association between small apolipoprotein(a) isoforms and frontotemporal dementia in humans

Apolipoprotein(a) [apo(a)] is a genetically polymorphic glycoprotein that has several similarities to apolipoprotein E. However, its role as a risk factor for frontotemporal dementia (FTD) remains to be elucidated. We therefore investigated the effect of an apo(a) polymorphism on the incidence of FTD in a sample of Caucasian Italian patients. From the entire group of FTD patients (n=54), 55.6% of the subjects had at least one apo(a) low molecular weight (MW) isoform, compared to 29.9% of non-demented controls (n=77). The difference between the two groups was statistically significant (odds ratio 2.93, 95% confidence interval 1.42-6.06, P=0.003). The FTD group was further divided into sporadic (n=26) and familial (n=28) cases. Even after such dichotomization, both sporadic and familial FTD patients showed a significantly higher prevalence of low MW apo(a) isoforms than the cognitively healthy controls (P=0.011 and P=0.025, respectively). Our data suggest a role of apo(a) phenotypes of low MW in mediating susceptibility to FTD.

Novel tau polymorphisms, tau haplotypes, and splicing in familial and sporadic frontotemporal dementia

BACKGROUND

A subset of familial cases (FTDP-17) of frontotemporal dementia (FTD) are caused by mutations in the tau gene. The role of tau gene mutations and haplotypes in sporadic FTD and the functional consequences of tau polymorphisms are unknown.

OBJECTIVES

To investigate (1) the frequency of known FTDP-17 mutations in familial and sporadic FTD and compare these results with previous studies; (2) whether the tau H1 haplotype is associated with FTD; and (3) the functional effect of intronic tau sequence variations.

PATIENTS AND METHODS

Patients with familial and sporadic FTD were screened for mutations in the microtubule-binding region of tau. The frequencies of tau haplotypes and genotypes were compared between patients with FTD and control subjects. We analyzed the splicing effect of novel intronic polymorphisms associated with FTD.

RESULTS

The P301L mutation was detected in 11% of familial FTD cases. The H1 haplotype was not overrepresented in patients with FTD, but the P301L mutation appeared on the background of the H2 tau haplotype. We identified 4 novel single nucleotide polymorphisms in intron 9 and a 9-base pair deletion in intron 4A. A C-to-T transition 177 base pairs upstream from exon 10 was significantly increased in patients with FTD compared with controls. Direct analysis of brain tissue from a patient with this variant showed an increase in exon 10-containing tau transcripts.

CONCLUSIONS

Sequence variations in intronic or regulatory regions of tau may have previously unrecognized consequences leading to tau dysfunction and neurodegeneration.

Redox Regulation of Apoptosis before and after Cytochrome C Release

Programmed cell death, or apoptosis, is one of the most studied areas of modern biology. Apoptosis is a genetically regulated process, which plays an essential role in the development and homeostasis of higher organisms. Mitochondria, known to play a central role in regulating cellular metabolism, was found to be critical for regulating apoptosis induced under both physiological and pathological conditions. Mitochondria are a major source of reactive oxygen species (ROS) but they can also serve as its target during the apoptosis process. Release of apoptogenic factors from mitochondria, the best known of which is cytochrome c, leads to assembly of a large apoptosis-inducing complex called the apoptosome. Cysteine proteases (called caspases) are recruited to this complex and, following their activation by proteolytic cleavage, activate other caspases, which in turn target for specific cleavage a large number of cellular proteins. The redox regulation of apoptosis during and after cytochrome c release is an area of intense investigation. This review summarizes what is known about the biological role of ROS and its targets in apoptosis with an emphasis on its intricate connections to mitochondria and the basic components of cell death.

Studies of the pathophysiological mechanisms in frontotemporal dementia by proteome analysis of CSF proteins

Comparative proteomic analysis of cerebrospinal fluid (CSF) proteins was employed for studies of the pathophysiological mechanisms in frontotemporal dementia (FTD). Two-dimensional gel electrophoresis and mass spectrometry were used for clinical screening of disease-influenced CSF proteins in 15 FTD patients compared to 12 controls. Six proteins were significantly altered in FTD compared to controls, including granin-like neuroendocrine precursor (proSAAS), pigment-epithelium derived factor (PEDF), retinol-binding protein (RBP), apoE, haptoglobin, and albumin. The levels of ProSAAS, PEDF, and RBP have not been shown earlier to be involved in the FTD pathology. Recently, we have also used proteomic analysis for studies of disease-influenced CSF proteins in Alzheimer's disease (AD) patients. The most clearly affected CSF proteins were the apolipoproteins in AD, compared to controls and FTD patients. ApoE seems to be influenced to a lesser degree in FTD compared to AD. Our data showed that several proteins involved in FTD pathology are not influenced in the CSF of AD patients, and vice versa, establishing differences in the pathophysiological mechanisms between FTD and AD, two of the most common neurodegenerative disorders.

Apolipoprotein E gene in frontotemporal dementia: an association study and meta-analysis

No definite genetic risk factor of non-monogenic frontotemporal dementia (FTD) has yet been identified. Several groups have examined the potential association of FTD with the apolipoprotein E (APOE) gene, but the results are inconsistent. Our objective was to determine whether APOE is a risk factor of FTD, using the largest series of patients with FTD and controls analysed so far (94 unrelated patients and 392 age and sex-matched controls), and a meta-analysis. Homozygosity for the E2E2 genotype was significantly associated with FTD (odds ratio (OR)=11.3; P=0.033, exact test). After stratification on familial history (FH) for FTD, the OR for E2E2 was still found significant when analysing only patients with a positive FH (OR=23.8; P=0.019). The meta-analysis, using 10 case-control studies with available genotype or allele information, comprising a total of 364 FTD patients and 2671 controls, including the patients of the present study, did not reach statistical significance even if the E2E2 genotype was more frequent in patients than in controls (0.018 vs 0.006, respectively). Because of studies heterogeneity (Mantel-Haenszel statistics: P=0.004), we analysed on one hand the neuropathologically-confirmed studies, and on the other hand the clinical-based studies. In the neuropathologically-confirmed studies (Mantel-Haenszel statistics: P=ns), we found a significant increase of the E2 allele frequency in FTD patients (OR[E2 vs E3]=2.01; 95% CI=1.02-3.98; P=0.04). The same result was found in the clinical-based studies, but studies heterogeneity remained. No result was significant with the E4 allele. The E2 allele seems so to be a risk factor of FTD whereas this allele is associated with the lowest risk in Alzheimer's disease. If this finding was confirmed, it could provide new insights into the mechanisms of differential risk related to APOE in neurodegenerative diseases.

Frontotemporal dementia classification and neuropsychiatry

BACKGROUND

Frontotemporal dementia (FTD) is a syndrome encompassing the clinical expression of frontal or temporal lobe degeneration. The many clinical phenotypes of FTD include primary progressive aphasias and a more common frontotemporal degeneration with less marked language alteration but significant behavioral changes.

SUMMARY

This paper describes the clinical progression of neuropsychiatric symptoms among 62 predominantly behavioral presentations and 30 language presentations of FTD. Disinhibition and depression became common for both subject groups over the course of illness. Significantly more cases presenting with behavioral changes had apathy and disinhibition.

CONCLUSIONS

Language presentations of FTD had longer latency to onset of distinct neuropsychiatric changes but eventually converge with the phenotype initially affected with behavioral change. Clinicians should anticipate such neuropsychiatric changes, prepare families for the course of illness in patients with either clinical presentation,treat symptomatically with psychotropic medications to help families cope with behaviorally disturbed patients.