Genetic study of Sardinian patients with Alzheimer's disease

Facets of Personality and Risk of Cognitive Impairment: Longitudinal Findings in a Rural Community from Sardinia

Background: Few studies have examined the associations between personality facets and dementia risk and rarely included individuals from rural settings or with low education. Objective: To examine the association between personality and the risk of cognitive impairment. Methods: Participants (N = 1,668; age 50 to 94 at baseline; 56.4% women; 86.5% less than high school diploma) were from a rural region of Sardinia (Italy) who completed the Revised NEO Personality Inventory (NEO-PI-R) during the first wave (2001–2004) and the Mini-Mental State Examination (MMSE) at waves two to five (2005–2021). Cox regression was used to test personality and covariates as predictors of cognitive impairment based on MMSE education-adjusted cutoffs. Results: During the up to 18-year follow-up (M = 10.38; SD = 4.76), 187 individuals (11.2%) scored as cognitively impaired. Participants with higher neuroticism (particularly the depression facet [HR = 1.22, 95% CI = 1.06–1.40]), and lower agreeableness (particularly the modesty facet [HR = 0.83, 95% CI = 0.71–0.97]) and lower conscientiousness (particularly the dutifulness facet [HR = 0.78, 95% CI = 0.67–0.92]) were at higher risk of cognitive impairment. Lower warmth ([HR = 0.75, 95% CI = 0.65–0.87], facet of extraversion) and ideas ([HR = 0.76, 95% CI = 0.65–0.89], facet of openness) were also associated with increased risk of impairment. These associations were virtually unchanged in models that accounted for other risk factors, including smoking, depression, obesity, hypertension, diabetes, and apolipoprotein E (APOE) ɛ4 carrier status. Across the five domains, sex and the APOE variant did not moderate the associations. Conclusion: In a sample with demographic characteristics underrepresented in dementia research, this study identifies personality domains and facets most relevant to the risk of cognitive impairment.

Activation of Tyrosine Phosphorylation Signaling in Erythrocytes of Patients with Alzheimer's Disease

Alzheimer's disease (AD) is the most prevalent type of dementia affecting older people. The identification of biomarkers is increasingly important and would be crucial for future therapy. Here, we demonstrated that in AD erythrocytes: (i) the anion transporter band3 is highly phosphorylated; (ii) the lyn kinase is phosphorylated and activated; (iii) the tyrosine phosphatase activity is downregulated, with a significant inverse correlation between band3 phosphorylation and disease progression, as revealed by Mini Mental State Examination score. Finally, we showed that in normal erythrocytes, treated in vitro with Aβ1-42 peptide, both band3 phosphorylation and lyn activation occurs. These results suggest that modulation of tyrosine phosphorylation signaling may be evaluated as a potential peripheral marker in AD.

Maysin and Its Flavonoid Derivative from Centipedegrass Attenuates Amyloid Plaques by Inducting Humoral Immune Response with Th2 Skewed Cytokine Response in the Tg (APPswe, PS1dE9) Alzheimer's Mouse Model

Alzheimer’s disease (AD) is a slow, progressive neurodegenerative disease and the most common type of dementia in the elderly. The etiology of AD and its underlying mechanism are still not clear. In a previous study, we found that an ethyl acetate extract of Centipedegrass (CG) (i.e., EA-CG) contained 4 types of Maysin derivatives, including Luteolin, Isoorientin, Rhamnosylisoorientin, and Derhamnosylmaysin, and showed protective effects against Amyloid beta (Aβ) by inhibiting oligomeric Aβ in cellular and in vitro models. Here, we examined the preventative effects of EA-CG treatment on the Aβ burden in the Tg (Mo/Hu APPswe PS1dE9) AD mouse model. We have investigated the EA-CG efficacy as novel anti-AD likely preventing amyloid plaques using immunofluorescence staining to visually analyze Aβ40/42 and fibril formation with Thioflavin-S or 6E10 which are the profile of immunoreactivity against epitope Aβ1–16 or neuritic plaque, the quantitation of humoral immune response against Aβ, and the inflammatory cytokine responses (Th1 and Th2) using ELISA and QRT-PCR. To minimize the toxicity of the extracted CG, we addressed the liver toxicity in response to the CG extract treatment in Tg mice using relevant markers, such as aspartate aminotransferase (AST)/ alanine aminotransferase (ALT) measurements in serum. The EA-CG extract significantly reduced the Aβ burden, the concentration of soluble Aβ40/42 protein, and fibril formation in the hippocampus and cortex of the Tg mice treated with EA-CG (50 mg/kg BW/day) for 6 months compared with the Tg mice treated with a normal diet. Additionally, the profile of anti-inflammatory cytokines revealed that the levels of Th2 (interleukin-4 (IL-4) and interleukin-10 (IL-10)) cytokines are more significantly increased than Th1 (interferon-γ (IFN-γ), interleukin-2(IL-2)) in the sera. These results suggest that the EA-CG fraction induces IL-4/IL-10-dependent anti-inflammatory cytokines (Th2) rather than pro-inflammatory cytokines (Th1), which are driven by IL-2/IFN-γ. With regard to the immune response, EA-CG induced an immunoglobulin IgG and IgM response against the EA-CG treatment in the Tg mice. Furthermore, EA-CG significantly ameliorated the level of soluble Aβ42 and Aβ40. Similarly, we observed that the fibril formation was also decreased by EA-CG treatment in the hippocampus and cortex after quantitative analysis with Thioflavin-S staining in the Tg brain tissues. Taken together, our findings suggested that Maysin and its derivative flavonoid compounds in the EA-CG fraction might be beneficial therapeutic treatments or alternative preventative measures to adjuvant for boosting humoral and cellular include immune response and anti-inflammation which may lead to amyloid plaque accumulation in Alzheimer’s patients’ brains.

SORL1 Gene is Associated with the Conversion from Mild Cognitive Impairment to Alzheimer's Disease

Several studies have established the sortilin-related receptor gene (SORL1) as a susceptibility locus for Alzheimer's disease (AD). Single nucleotide polymorphisms of SORL1 reported in literature as being associated with AD were investigated in an Italian case-control data set, and their role as a risk factor of conversion to AD was studied in an independent sample of subjects diagnosed with mild cognitive impairment (MCI) at baseline. rs641120, rs2070045, and rs1010159 were genotyped in 734 subjects diagnosed with AD (n = 338) and MCI (n = 181) and in healthy controls (n = 215). Our results confirmed the association between rs641120 and AD (p = 0.01). In the MCI cohort, rs1010159 was associated with conversion to AD (HR = 1.56, p = 0.002). Taken together, these findings confirm that SORL1 is associated with AD and might be a potential tool for identifying MCI subjects at high risk of conversion to AD.

Binge eating and fast cognitive worsening in an early-onset bvFTD patient carrying C9ORF72 expansion

An expanded hexanucleotide (GGGGCC) repeat in a non-coding promoter region of open reading frame 72 of chromosome 9 (C9ORF72) has been recently identified as a major cause of familial and sporadic frontotemporal lobar degeneration. We describe the clinical picture of a 64-year-old woman carrying the hexanucleotide repeat expansion, who developed a sporadic early-onset form of behavioral variant frontotemporal dementia characterized by the occurrence of uncommon behavioral manifestations such as binge eating disturbance and by a rapid worsening of cognitive abilities. Our report confirms previous studies asserting that C9ORF72 repeats may sustain heterogeneous clinical syndromes.

Functional and genetic analysis of haplotypic sequence variation at the nicastrin genomic locus

Nicastrin (NCSTN) is a component of the γ-secretase complex and therefore potentially a candidate risk gene for Alzheimer's disease. Here, we have developed a novel functional genomics methodology to express common locus haplotypes to assess functional differences. DNA recombination was used to engineer 5 bacterial artificial chromosomes (BACs) to each express a different haplotype of the NCSTN locus. Each NCSTN-BAC was delivered to knockout nicastrin (Ncstn(-/-)) cells and clonal NCSTN-BAC(+)/Ncstn(-/-) cell lines were created for functional analyses. We showed that all NCSTN-BAC haplotypes expressed nicastrin protein and rescued γ-secretase activity and amyloid beta (Aβ) production in NCSTN-BAC(+)/Ncstn(-/-) lines. We then showed that genetic variation at the NCSTN locus affected alternative splicing in human postmortem brain tissue. However, there was no robust functional difference between clonal cell lines rescued by each of the 5 different haplotypes. Finally, there was no statistically significant association of NCSTN with disease risk in the 4 cohorts. We therefore conclude that it is unlikely that common variation at the NCSTN locus is a risk factor for Alzheimer's disease.

High APOE epsilon 4 allele frequencies associated with Alzheimer disease in a Tunisian population

The goal of the study was to examine the Apolipoprotein E (APOE) genotypes in a Tunisian sample of patients with Alzheimer disease (AD) and normal controls, and to compare the results with the findings from the literature. A hospital-based case-control study of two groups (58 patients with AD, 71 controls) was conducted. Patients received a detailed clinical history, neurological examination, neuropsychological testing and brain imaging. A neurological examination and the Arabic version of the Mini-Mental State Examination were made for controls. Genotyping was performed using the PCR restriction fragment length polymorphism (PCR-RFLP) method. There were no statistical differences in age (p = 0.05) and gender (p = 0.046) between the two groups. The APOE ε4/4 genotype was over represented in the AD group in comparison with the controls (13.3 vs. 2.8%). A significant increased risk of AD among APOE ε4 allele carriers was observed. The odds ratio for the association of AD patients with homozygous and heterozygous ε4 allele was, respectively, 5.40 (1.35-21.48) and 2.90 (1.27-6.62). Our results in addition to previously published genetic studies suggest that AD disease is multifactor in origin. Ethnicity, genetic and environmental factors contribute to AD risk in different ethnic groups.

A novel PSENEN mutation in a patient with complaints of memory loss and a family history of dementia

Presenilin enhancer-2 (PSENEN) is a fundamental component of the gamma-secretase protein complex involved in beta-amyloid precursor protein (beta APP) processing, a key event in Alzheimer's disease (AD) etiopathogenesis. In a mild cognitive impairment (MCI)-diagnosed woman, belonging to a family with a positive history for AD, we found that a novel PSENEN mutation (S73F) was the only genetic alteration of relevance. The mutation was absent in 253 age-matched controls. In an attempt to learn the biochemical effects of this mutation, we cultured skin primary fibroblasts from the patient and her daughter, and we assessed A beta(1-40) and Abeta(1-42) production. We did not find any relevant differences in comparison to age-matched, normal subjects. Although our data do not definitively support a pathogenetic role for this mutation, it does not appear to be a common polymorphism. Further follow-up is warranted in this family.

Association between promoter polymorphisms of the nicastrin gene and sporadic Alzheimer's disease in North Chinese Han population

Increasing evidences have shown that nicastrin (NCSTN) plays a crucial role in gamma-cleavage of the amyloid precursor protein (APP). Inhibition of NCSTN demonstrated an altered gamma-cleavage activity, suggesting its potential implication in developing Alzheimer's disease (AD). We detected the NCSTN gene promoter region in 359 sporadic AD (SAD) patients and 331 controls and found three promoter single nucleotide polymorphisms (SNPs): -1216C/A (rs2147471), -796T/G (rs10752637) and -436C/T (rs1324738). For -1216C/A, there were significant differences in the allele and genotype frequency between AD and control subjects (allele P=0.031, genotype P=0.017). The allele and genotype frequencies remained significant before and after APOEvarepsilon4 stratification. The -1216CC carriers increased 2-fold risk for the development of SAD compared to the carriers with -1216CA and AA genotypes (OR=2.049, 95%CI=1.410-2.976, P=0.000). For -796T/G, there were significant differences in the genotype frequency between SAD and control subjects (P=0.009). This trend is still obvious in the subjects without APOEvarepsilon4 allele. The -796GG carriers might decrease the risk compared to the carriers with -796TG and TT genotypes (OR=0.602, 95%CI=0.393-0.932, P=0.022). No significant difference was detected either in genotype or in allele frequencies between SAD and control for -436C/T, even after APOEvarepsilon4 stratification. The haplotype -1216A/-796G may be a protective factor for SAD (OR=0.795, 95%CI=0.636-0.995, P=0.045). Our investigation suggests that -1216C/A and -796T/G are probably related to the development of SAD.

Alzheimer's disease: case-control association study of polymorphisms in ACHE, CHAT, and BCHE genes in a Sardinian sample

Alzheimer's disease (AD) is characterized by an extensive loss of cholinergic neurons, and their cortical projections, from the basal forebrain area. The resulting reduction in cholinergic activity is associated with decreased levels of the neurotransmitter acetylcholine (ACh), decreased activity of acetylcholinesterase (AChE), choline acetyltransferase (ChAT), and increased butyrylcholinesterase (BChE) activity. In the present study, we investigated whether the BCHE, ACHE, and CHAT genes were associated with AD and the possibility of a synergistic effect with APOE-epsilon4 in a Sardinian sample. AD patients (n = 158), exclusively of Sardinian ancestry, were recruited from the Division of Geriatrics Local Health Agency 8 and Unit of Clinical Pharmacology, Department of Neurosciences, University of Cagliari. Patients were diagnosed according to DSM-IV, and National Institute of Neurologic and Communicative Disorders and Stroke-AD and Related Disorders Association (NINCDS-ADRDA) criteria for possible or probable AD. Cognitive screening was performed by means of Mini-Mental State Examination (MMSE). Healthy controls (n = 118) of Sardinian ancestry were recruited from religious and sport associations. All patients and control subjects gave informed consent for participation in the study. Single nucleotide polymorphism (SNP) analysis was performed by PCR/RFLP or the TaqMan 5' exonuclease method. Our study confirms the association between APOE epsilon4 allele and AD (P < 0.000). No significant differences were observed in allele and genotype frequencies of BCHE, ACHE, and CHAT between AD and controls. Haplotype analysis of ACHE SNPs did not reveal a significant association between ACHE and AD. Our results suggest that the AChE, ChAT, and BChE polymorphisms do not constitute a major genetic risk factor for susceptibility to AD in a Sardinian population.

A mutation screening by DHPLC of PSEN1 and APP genes reveals no significant variation associated with the sporadic late-onset form of Alzheimer's disease

Alzheimer's disease (AD), the most common cause of dementia in the elderly, is usually divided into familial and sporadic forms, according to family history. The familial form has often been reportedly caused by mutations in amyloid precursor protein (APP), presenilin-1 (PSEN1), or presenilin-2 (PSEN2) genes, whereas the genetic component for the sporadic form is less clear. We carried out mutation screening in exons 16 and 17 of APP, and in exons 3, 4, 5, 6, 7, 10 of PSEN1 genes in patients with the sporadic late-onset form of AD (LOAD). The aim of this study was to ascertain whether any variation in these genes, besides that of the well-known apolipoprotein E common polymorphism, could be involved in the onset of the disease. To search for the single nucleotide substitutions, we examined 172 LOAD patients by the denaturing high-performance liquid chromatography (DHPLC) technique. Only one same-sense mutation in exon 4 of PSEN1 gene (N32) was observed in this patient group. We concluded that the variation in the screened exons of the APP and PSEN1 genes, reportedly associated with familial AD, is not present in LOAD.

Determination of malondialdehyde, reduced glutathione levels and APOE4 allele frequency in late-onset Alzheimer's disease in Denizli, Turkey

OBJECTIVES

The aim of the present study was to determine the Apolipoprotein E (APOE) 4 allele frequency of patients with late-onset Alzheimer's disease (AD) and to determine the effects of oxidant-antioxidant balance on AD.

DESIGN AND METHODS

PCR-RFLP was undertaken in 62 cases with AD and 56 aged-matched controls. Activities of reduced glutathione (GSH) and malondialdehyde (MDA) concentration were measured in same groups.

RESULTS

Patients with at least one E4 allele genotype were significantly different in patients with AD (21%) than controls (9%) (p=0.01). Serum MDA levels were significantly different between AD patients and Control group (p=0.0001). There was no significant difference in serum GSH levels between AD patients and C groups.

CONCLUSION

These results confirmed that the APOE4 allele occurs frequently in late onset AD compared with normal controls. Also elevated MDA levels are likely an essential factor in the pathogenesis and neuronal damage of AD.