A simple and efficient method for apolipoprotein E genotype determination

Coffee and tea consumption and dementia risk: The role of sex and vascular comorbidities

BACKGROUND

Coffee and tea consumption has been linked to dementia. However, it remained unknown how sex and vascular risk factors modify the association. We aimed to investigate the association of coffee and tea consumption with dementia and whether sex and vascular comorbidities modified the association.

METHODS

We included 278 elderly patients with Alzheimer's disease (AD) and 102 patients with vascular dementia (VaD) from three hospitals; controls (N = 468) were recruited during the same period. We collected the frequency and amount of coffee and tea consumption and the presence of vascular comorbidities. The multinomial logistic regression model was utilized to evaluate the association of coffee and tea consumption with dementia, stratified by sex and vascular comorbidities.

RESULTS

Different combinations and quantities of coffee and tea consumption protected against AD and VaD. Consumption of ≥3 cups of coffee or tea per day was protective against AD [adjusted odds ratio (aOR) = 0.42; 95% confidence interval (CI) = 0.22-0.78)] and VaD (aOR = 0.42; 95% CI = 0.19-0.94). Stratified analyses showed that the protective effects of a higher quantity of coffee and tea against AD were more pronounced among females and individuals with hypertension. Consumption of either coffee or tea was associated with a decreased risk of VaD among diabetic participants (aOR = 0.23; 95% CI = 0.06-0.98). Hyperlipidemia modified the association of coffee or tea consumption on the risk of AD and VaD (both Pinteraction < 0.01).

CONCLUSION

The risk of AD and VaD was lower with increased consumption of coffee and tea; the impact differed by sex and vascular comorbidities including hypertension, hyperlipidemia, and diabetes.

Association of subclinical depressive symptoms and sleep with cognition in the community-dwelling older adults

BACKGROUND

/Purpose: This study aimed to explore the association of subclinical depressive symptoms and sleep with cognition in community-dwelling Taiwanese older adults.

METHODS

This four-year prospective cohort study (2015-2019) included 379 participants aged 65 years or older from the annual senior health checkup program at National Taiwan University Hospital who were followed up two years later. Global and domain cognitive functions were assessed using validated neuropsychological tests. Depressive symptoms were evaluated using the Center for Epidemiologic Studies Depression (CES-D) Scale. Sleep quality was evaluated using the Pittsburg Sleep Quality Index (PSQI). Excessive daytime sleepiness was assessed using the Epworth Sleepiness Scale (ESS). Generalized linear mixed models were used to explore the associations of subclinical depressive symptoms and sleep variables with cognition, adjusting for important covariates. Stratification analyses were performed using the sleep variables.

RESULTS

Over time, depressive symptoms were associated with poor performance of memory (βˆ = 0.24, P = 0.04) and executive function (βˆ = -0.24, P = 0.03). Poor sleep quality (elevated PSQI score) was associated with poor memory performance (βˆ = -0.04 to -0.03, P < 0.05). Excessive daytime sleepiness (elevated ESS score) was associated with poor performance of memory (βˆ = -0.02, P < 0.05) and executive function (βˆ = -0.02, P = 0.001). At baseline, better sleep quality and no excessive daytime sleepiness were associated with better memory performance over time.

CONCLUSION

Subclinical depressive symptoms, worse sleep quality, and excessive daytime sleepiness were differentially associated with impairment of cognitive domains (mainly memory and executive function).

Impacts of Kidney Dysfunction and Cerebral Cortical Thinning on Cognitive Change in Elderly Population

BACKGROUND

Cerebral cortical thickness is a neuroimaging biomarker to predict cognitive decline, and kidney dysfunction (KD) is associated with cortical thinning.

OBJECTIVE

This study aimed to investigate the effects of KD and cortical thinning on cognitive change in a prospective cohort study.

METHODS

A total of 244 non-demented participants were recruited from elderly health checkup program and received cognitive exams including Montreal Cognitive Assessment (MoCA) and different cognitive domains at baseline and three biannual follow-ups afterwards. KD was defined as having either glomerular filtration rate <60 ml/min/1.73 m2 or proteinuria. Cortical thickness of global, lobar, and Alzheimer's disease (AD) signature area were derived from magnetic resonance imaging at baseline, and cortical thinning was defined as the lowest tertile of cortical thickness. Generalized linear mixed models were applied to evaluate the effects of KD and cortical thinning on cognitive changes.

RESULTS

KD was significantly associated with the decline in attention function (β= -0.29). Thinning of global (β= -0.06), AD signature area (β= -0.06), temporal (β= -0.06), and parietal lobes (β= -0.06) predicted poor verbal fluency over time, while temporal lobe thinning also predicted poor MoCA score (β= -0.19). KD modified the relationship between thinning of global, frontal, and limbic, and change of logical memory function (pinteraction < 0.05). When considering jointly, participants with both KD and cortical thinning had greatest decline in attention function compared with those without KD or cortical thinning (β= -0.51, ptrend = 0.008).

CONCLUSIONS

KD and cortical thinning have joint effect on cognitive decline, especially the attention function. Reverse associations may exist between cortical thinning and memory function in participants with KD, though the results should be interpreted cautiously as an exploratory analysis.

NGF (-198C > T, Ala35Val) and p75NTR (Ser205Leu) gene mutations are associated with liver function in different histopathological profiles of the patients with chronic viral hepatitis in the Brazilian Amazon

BACKGROUNDS

Neural growth factor (NGF) is a neurotrophin that can interact with the p75NTR receptor and initiate a cascade of reactions that determines cell survival or death, and both are associated with the physiology of liver tissue. Single nucleotide polymorphisms (SNPs) in the NGF and p75NTR genes have been investigated in different pathologies; however, there are no studies that have analyzed their biological roles in the hepatic microenvironment. In the present study, we evaluated the impact of SNPs in these genes on the maintenance of liver function at different stages of inflammation and fibrosis in patients with chronic viral liver disease in the Brazilian Amazon.

METHODS

The SNPs -198C > T, Arg80Gln, Val72Met, Ala35Val, Ala18Ala and Ser205Leu were genotyped by real-time PCR in samples from patients with chronic viral hepatitis stratified by stage of inflammation and liver fibrosis. Histopathological, viral load (VL), liver enzyme and comorbidities data were obtained from updated medical records. Other aspects were highlighted by applied epidemiological questionnaires.

RESULTS

The -198C/T and Ala35Val polymorphisms in NGF were associated with changes in histopathological profiles, VL and liver enzymes. Ser205Leu polymorphism in p75NTR was associated only with changes in VL and liver enzymes. Polymorphic frequencies were variable among different ethnic populations, mainly for biologically relevant polymorphisms. A multifactorial network of interactions has been established based on genetic, virological, behavioral and biochemical aspects.

CONCLUSION

Mutations in the NGF (-198C > T, Ala35Val) and p75NTR (Ser205Leu) genes, within the list of multifactorial aspects, are associated with liver function in different histopathological profiles of patients with chronic viral liver disease in the Brazilian Amazon.

The effect of lifestyle on late-life cognitive change under different socioeconomic status

This study aimed to identify lifestyle factors associated with cognitive change and to explore whether the effect of lifestyle varies by socioeconomic status (SES). Participants aged 65 years and older were recruited from elderly health checkup programs from 2011 to 2013 in Taiwan. Neuropsychological tests, including tests of global cognition, logical memory, executive function, verbal fluency and attention, were administered at baseline (N = 603) and 2 years later (N = 509). After literature review, 9 lifestyle factors and 3 SES indicators were chosen and their effects on cognitive change were evaluated using linear regression adjusting for age, sex, education, APOE ε4 status, and baseline cognitive score. Five lifestyle factors (high vegetable and fish intake, regular exercise, not smoking, and light to moderate alcohol consumption) and 3 SES indicators [annual household income (> 33,333 USD vs. less), occupational complexity (high vs. low mental demanding job), and years of education (> 12 years vs. less)] were found to be protective against cognitive decline (P < 0.1 in any cognitive domains, ß ranging from 0.06 to 0.38). After further adjusting for all the lifestyle and SES factors, fish intake, higher income and occupational complexity remained protective. Significant interactions were found between a healthful lifestyle (defined as having ≥ 3 healthful lifestyle factors) and income on changes of global cognition and verbal fluency (P_interaction = 0.02 and 0.04). The protective effect of a healthful lifestyle was observed only among participants with lower income in global cognition and logical memory [ß = 0.17, 95% confidence interval (CI) = 0.07–0.26; ß = 0.30, 95% CI = 0.14–0.46]. To the best of our knowledge, this study for the first time explored how the interactions of lifestyle and SES affect cognitive change. Our findings will aid in developing dementia prevention programs and reduce health inequalities.

Association of apolipoprotein E and myeloperoxidase genotypes to clinical course of familial and sporadic multiple sclerosis

The importance of apolipoprotein E (ApoE) and myeloperoxidase (MPO) genotypes in the clinical characteristics of multiple sclerosis (MS) has been recently emphasized. In a large group of Polish patients we have tested the hypothesis that polymorphism in ApoE and MPO genes may influence the course of the disease. G enotypes were determined in 117 MS patients (74 females and 43 males; 99 sporadic and 18 familial cases) with mean EDSS of 3.6, mean age of 44.1 years, mean duration of the disease 12.8 years and mean onset of MS at 31.2 years, and in 100 healthy controls. The relationship between ApoE and MPO genes’ polymorphism and the MS activity as well as the defect of remyelination (diffuse demyelination) and brain atrophy on MRI were analysed. The ApoE o4 allele was not related to the disease course or the ApoE o2 to the intensity of demyelination on MRI. The genotype MPO G/G was found in all familial MS and in 57% (56/99) of sporadic cases. This genotype was also related to more pronounced brain atrophy on MRI. The MPO G/G subpopulation was characterized by a significantly higher proportion of patients with secondary progressive MS (PB- 0.05) and by a higher value of EDSS. A ccording to our results the MPO G allele is frequently found (in 96% of cases) among Polish patients with MS. More severe nervous tissue damage in the MPO G/G form can be explained by the mechanism of accelerated oxidative stress. It seems that MPO G/G genotype may be one of the genetic factors influencing the progression rate of disability in MS patients.

CHRNA7 Polymorphisms and Dementia Risk: Interactions with Apolipoprotein ε4 and Cigarette Smoking

α7 nicotinic acetylcholine receptor (α7nAChR, encoded by CHRNA7) is involved in dementia pathogenesis through cholinergic neurotransmission, neuroprotection and interactions with amyloid-β. Smoking promotes atherosclerosis and increases dementia risk, but nicotine exerts neuroprotective effect via α7nAChR in preclinical studies. No studies explored the gene-gene, gene-environment interactions between CHRNA7 polymorphism, apolipoprotein E (APOE) ε4 status and smoking on dementia risk. This case-control study recruited 254 late-onset Alzheimer’s disease (LOAD) and 115 vascular dementia (VaD) cases (age ≥65) from the neurology clinics of three teaching hospitals in Taiwan during 2007–2010. Controls (N = 435) were recruited from health checkup programs and volunteers during the same period. Nine CHRNA7 haplotype-tagging single nucleotide polymorphisms representative for Taiwanese were genotyped. Among APOE ε4 non-carriers, CHRNA7 rs7179008 variant carriers had significantly decreased LOAD risk after correction for multiple tests (GG + AG vs. AA: adjusted odds ratio = 0.29, 95% confidence interval = 0.13–0.64, P = 0.002). Similar findings were observed for carriers of GT haplotype in CHRNA7 block4. A significant interaction was found between rs7179008, GT haplotype in block4 and APOE ε4 on LOAD risk. rs7179008 variant also reduced the detrimental effect of smoking on LOAD risk. No significant association was found between CHRNA7 and VaD. These findings help to understand dementia pathogenesis.

Amplification refractory mutation system polymerase chain reaction versus optimized polymerase chain reaction restriction-fragment length polymorphism for apolipoprotein E genotyping of majorly depressed patients

Major depressive disorder (MDD) is a prevalent, debilitating mood disorder that has been associated with several genetic polymorphisms. One such polymorphism, namely that of apolipoprotein E (APOE), has three allelic forms (ε2, ε3 and ε4) that encode for six unique isoforms of the APOE protein. A growing number of techniques have been developed for APOE genotyping; however, not all polymerase chain reaction (PCR)‑based genotyping techniques are equally accurate or cost‑effective. In order to find a more accurate and cost‑effective APOE genotyping method for MDD screening in large populations, the present study comparatively evaluated two genotyping methods, amplification refractory mutation system PCR (ARMS‑PCR) and optimized PCR restriction‑fragment length polymorphism (PCR‑RFLP), in blood samples taken from a population of 708 MDD patients. Although either of the two methods were able to detect all six unique APOE genotypes, comparisons of the two methods with Sanger sequencing demonstrated that ARMS‑PCR (94%) was significantly more accurate than optimized PCR‑RFLP (82%). ARMS‑PCR should prove useful in quickly verifying ambiguous results obtained by other APOE genotyping methods and can be cost-effectively performed in the setting of a small laboratory or a population-based screening program.

CHRNA7 polymorphisms and response to cholinesterase inhibitors in Alzheimer's disease

Background

CHRNA7 encodes the α7 nicotinic acetylcholine receptor subunit, which is important to Alzheimer's disease (AD) pathogenesis and cholinergic neurotransmission. Previously, CHRNA7 polymorphisms have not been related to cholinesterase inhibitors (ChEI) response.

Methods

Mild to moderate AD patients received ChEIs were recruited from the neurology clinics of three teaching hospitals from 2007 to 2010 (n = 204). Nine haplotype-tagging single nucleotide polymorphisms of CHRNA7 were genotyped. Cognitive responders were those showing improvement in the Mini-Mental State Examination score ≧2 between baseline and 6 months after ChEI treatment.

Results

AD women carrying rs8024987 variants [GG+GC vs. CC: adjusted odds ratio (AOR) = 3.62, 95% confidence interval (CI) = 1.47–8.89] and GG haplotype in block1 (AOR = 3.34, 95% CI = 1.38–8.06) had significantly better response to ChEIs (false discovery rate <0.05). These variant carriers using galantamine were 11 times more likely to be responders than female non-carriers using donepezil or rivastigmine.

Conclusion

For the first time, this study found a significant association between CHRNA7 polymorphisms and better ChEI response. If confirmed by further studies, CHRNA7 polymorphisms may aid in predicting ChEI response and refining treatment choice.

Sequence variants of toll like receptor 4 and late-onset Alzheimer's disease

Background

Toll like receptor 4 (TLR4) has been related to inflammation and beta-amyloid deposition in Alzheimer's disease (AD) brain. No study has explored the association between haplotype-tagging single nucleotide polymorphisms (htSNPs) of TLR4 and AD risk previously and ApoE e4 status alone showed low sensitivity in identifying late-onset AD (LOAD) patients.

Methods

A total of 269 LOAD patients were recruited from three hospitals in northern Taiwan (2007–2010). Controls (n = 449) were recruited from elderly health checkup and volunteers of the hospital during the same period of time. Five common (frequency≥5%) TLR4 htSNPs were selected to assess the association between TLR4 polymorphisms and the risk of LOAD in the Chinese ethnic population.

Results

Homozygosity of TLR4 rs1927907 was significantly associated with an increased risk of LOAD [TT vs. CC: adjusted odds ratio (AOR) = 2.45, 95% confidence interval (CI) = 1.30–4.64]. After stratification, the association increased further in ApoE e4 non-carriers (AOR = 3.07) and in hypertensive patients (AOR = 3.60). Haplotype GACGG was associated with a decreased risk of LOAD (1 vs. 0 copies: AOR = 0.59, 95% CI = 0.36–0.96; 2 vs. 0 copies: AOR = 0.31, 95% CI = 0.14–0.67) in ApoE e4 non-carriers. ApoE e4 status significantly modified this association (p_interaction = 0.01). These associations remained significant after correction for multiple tests.

Conclusions

Sequence variants of TLR4 were associated with an increased risk of LOAD, especially in ApoE e4 non-carriers and in hypertensive patients. The combination of TLR4 rs1927907 and ApoE e4 significantly increased the screening sensitivity in identifying LOAD patients from 0.4 to 0.7.

Different clinical phenotypes in siblings with a presenilin-1 P264L mutation

BACKGROUND

Mutations in the presenilin-1 gene (PSEN1) have been identified in autosomal dominant early-onset cases of Alzheimer's disease (AD).

AIMS

To investigate different clinical phenotypes of siblings possessing the same heterozygous P264L mutation in the PSEN1 gene.

METHODS

We evaluated clinical features, neuroimaging results, and neuropsychological examinations. The PSEN1 gene and other dementia-related gene mutations were screened.

RESULTS

We clinically diagnosed the proband as atypical AD with frontotemporal dementia features and diagnosed the elder brother of the proband as typical AD, based on neuropsychological symptoms and a brain imaging examination including amyloid imaging data. A heterozygous P264L mutation in the PSEN1 gene was identified in both siblings.

CONCLUSION

This study is one of few reports of AD siblings possessing the same mutation but exhibiting different clinical phenotypes in a Japanese family possessing a P264L mutation in the PSEN1 gene. The current results suggest that unknown modifiers, including both genetic and epigenetic factors, may alter the pathological and clinical phenotypes of a genetically predetermined disease.

PRND 3'UTR polymorphism may be associated with behavioral disturbances in Alzheimer disease

The etiology of behavioral and psychological symptoms of dementia (BPSD) is complex, including putative biological, psychological, social and environmental factors. Recent years have witnessed accumulation of data on the association between genetic factors and behavioral abnormalities in Alzheimer disease (AD). In this research paper, our aim is to evaluate the association between the APOE, CYP46, PRNP and PRND genes and the profile of neuropsychiatric symptoms in Polish subjects with AD and mild cognitive impairment (MCI). We studied 99 patients with AD and 48 subjects with MCI. The presence and profile of BPSD were evaluated at baseline and prospectively with the Neuropsychiatric Inventory (NPI). Patients were dichotomized into those having ever experienced a particular symptom and those who did not over the whole disease period. Genotyping was performed using previously described standard protocols. The prevalence of comorbid behavioral symptoms and the overall level of behavioral burden were significantly greater in AD compared with the MCI group. In AD patients, carrier status of the T allele of the 3'UTR (untranslated region) PRND polymorphism was associated with an increased cumulative behavioral load and an elevated risk for delusions, anxiety, agitation/aggression, apathy and irritability/emotional ability. Among MCI subjects, APOE ε4 carriers demonstrated a reduced risk for nighttime behavior change. No other statistically significant genotype-phenotype correlations were observed, including the APOE, CYP46 and PRNP genes. A precise estimation of the exact significance of particular polymorphisms in BPSD etiology requires future studies on large populations.

Sequence variants of interleukin 6 (IL-6) are significantly associated with a decreased risk of late-onset Alzheimer's disease

BACKGROUND

Interleukin 6 (IL-6) has been related to beta-amyloid aggregation and the appearance of hyperphosphorylated tau in Alzheimer's disease (AD) brain. However, previous studies relating IL-6 genetic polymorphisms to AD included few and unrepresentative single nucleotide polymorphisms (SNPs) and the results were inconsistent.

METHODS

This is a case-control study. A total of 266 patients with AD, aged≧65, were recruited from three hospitals in Taiwan (2007-2010). Controls (n = 444) were recruited from routine health checkups and volunteers of the hospital during the same period of time. Three common IL-6 haplotype-tagging SNPs were selected to assess the association between IL-6 polymorphisms and the risk of late-onset AD (LOAD).

RESULTS

Variant carriers of IL-6 rs1800796 and rs1524107 were significantly associated with a reduced risk of LOAD [(GG + GC vs. CC): adjusted odds ratio (AOR) = 0.64 and (CC + CT vs. TT): AOR = 0.60, respectively]. Haplotype CAT was associated with a decreased risk of LOAD (0 and 1 copy vs. 2 copies: AOR = 0.65, 95% CI = 0.44-0.95). These associations remained significant in ApoE e4 non-carriers only. Hypertension significantly modified the association between rs2069837 polymorphisms and the risk of LOAD (pinteraction = 0.03).

CONCLUSIONS

IL-6 polymorphisms are associated with reduced risk of LOAD, especially in ApoE e4 non-carriers. This study identified genetic markers for predicting LOAD in ApoE e4 non-carriers.

Genetic polymorphisms of nerve growth factor receptor (NGFR) and the risk of Alzheimer's disease

Background

Loss of basal forebrain cholinergic neurons is attributable to the proapoptotic signaling induced by nerve growth factor receptor (NGFR) and may link to Alzheimer's disease (AD) risk. Only one study has investigated the association between NGFR polymorphisms and the risk of AD in an Italian population. Type 2 diabetes mellitus (DM) may modify this association based on previous animal and epidemiologic studies.

Methods

This was a case-control study in a Chinese population. A total of 264 AD patients were recruited from three teaching hospitals between 2007 to 2010; 389 controls were recruited from elderly health checkup and volunteers of the hospital during the same period of time. Five common (frequency≥5%) haplotype-tagging single nucleotide polymorphisms (htSNPs) were selected from NGFR to test the association between NGFR htSNPs and the risk of AD.

Results

Variant NGFR rs734194 was significantly associated with a decreased risk of AD [GG vs. TT copies: adjusted odds ratio (OR) = 0.43, 95% confidence interval (CI) = 0.20-0.95]. Seven common haplotypes were identified. Minor haplotype GCGCG was significantly associated with a decreased risk of AD (2 vs. 0 copies: adjusted OR = 0.39, 95% CI = 0.17-0.91). Type 2 DM significantly modified the association between rs2072446, rs741072, and haplotype GCTTG and GTTCG on the risk of AD among ApoE ε4 non-carriers (P_interaction < 0.05).

Conclusion

Inherited polymorphisms of NGFR were associated with the risk of AD; results were not significant after correction for multiple tests. This association was further modified by the status of type 2 DM.

Familial semantic dementia with P301L mutation in the Tau gene

BACKGROUND/AIMS

Semantic dementia (SD) is a clinical subclassification of frontotemporal lobar degeneration. Patients with 'pure SD' present with semantic memory impairment preceding the frontal symptoms, and there have been no reports of familial cases.

METHODS

We evaluated the clinical features of, and performed neuropsychological examinations on, the proband and two affected family members. Then we performed neuroimaging and genetic analysis of MAPT and other dementia-related genes in the proband.

RESULTS

All three cases had semantic memory impairment with loss of word meanings as the primary early symptom. We diagnosed all cases as pure SD and identified a P301L mutation in the MAPT gene of the proband.

CONCLUSION

Although the P301L mutation identified here has been previously described as pathogenic for frontotemporal dementia with parkinsonism-17 (FTDP-17), the proband and his two affected relatives showed different clinical symptoms from those of typical FTDP-17 cases who carry the P301L mutation. Pathologically, pure SD usually shows a TAR DNA-binding protein proteinopathy, but the molecular understanding of SD is not well established. Although our cases were clinically pure SD, the proband has a tau gene mutation, which would lead to tauopathy. These findings suggest that reconsideration of the molecular understanding of SD is warranted.

Association of apolipoprotein E polymorphisms with temporal lobe epilepsy in a Chinese Han population

Apolipoprotein E (ApoE) has been implicated as one of the susceptibility genes for temporal lobe epilepsy (TLE). Previous studies indicate that ApoE ɛ4 is associated with several disease-related traits including the increased risk of late posttraumatic seizures, earlier onset of TLE, refractory complex partial seizures, and postictal confusion. Contradictory data were also reported regarding the association between ApoE polymorphisms and TLE. The present study was designed to investigate whether ApoE ɛ4 is a risk factor for TLE and the above clinical variables, as well as to determine whether -491A/T polymorphism may independently alter the risk for TLE in a Chinese Han population. The ApoE and -491A/T polymorphisms were genotyped in 558 controls and 735 patients including 560 TLE patients using polymerase chain reaction-restriction fragment length polymorphism. A significant association was detected between prior trauma and the ApoE ɛ4 allele in TLE patients. However, no significant differences were observed in the genotype and haplotype distributions and allele frequencies of these two polymorphisms between cases and controls. Furthermore, there were no significant associations between these two polymorphisms and the other clinical variables examined. The study illustrates that the ApoE ɛ4 allele may be involved in the development of TLE in those patients with prior trauma in the Chinese Han population.

Genetic polymorphisms of a novel vascular susceptibility gene, Ninjurin2 (NINJ2), are associated with a decreased risk of Alzheimer's disease

Background

Accumulated evidences have shown that vascular risk factors, e.g., hypertension, diabetes mellitus and hyperlipidemia, may be related to the risk of dementia. This study investigated the association between genetic polymorphisms of a vascular susceptibility gene, Ninjurin2 (NINJ2), and the risk of dementia, which has not been explored previously.

Methods

A total of 275 Alzheimer's disease (AD) patients and 119 vascular dementia (VaD) patients aged 50 or older were recruited from three teaching hospitals from 2007 to 2010. Healthy controls (n = 423) with the same age of cases were recruited from the health checkup and volunteers worked at the hospital during the same time period. Five common (frequency >5%) haplotype-tagging single nucleotide polymorphisms (htSNPs) in NINJ2 were genotyped to test for the association between sequence variants of NINJ2 and dementia risk, and how vascular risk factors modify this association.

Results

Homozygosity of two NINJ2 SNPs was significantly associated with a decreased risk of AD [rs11833579: adjusted odds ratio (AOR) = 0.43; 95% confidence interval (CI)  = 0.23–0.80; rs12425791: AOR  = 0.33, 95% CI  = 0.12–0.96]. Five common haplotypes (cumulative frequency  = 97%) were identified. The global test for the association between NINJ2 haplotypes and AD was significant (p = 0.03). Haplotype CAGGA was significantly associated with a decreased risk of AD (AOR  = 0.32, 95% CI  = 0.11–0.94). No associations were observed for VaD.

Conclusion

Inherited polymorphisms of the vascular susceptibility gene NINJ2 were associated with AD risk.

The role of apolipoprotein E polymorphisms in levodopa-induced dyskinesia

OBJECTIVES

To determine the relationship between apolipoprotein E (APOE) polymorphisms to the time to appearance of levodopa-induced dyskinesia (LID) in patients with Parkinson's disease.

METHODS

The APOE genotype of 155 consecutive patients treated with levodopa was determined and its effect on the time of onset of LID was examined using Cox regression model, controlling for gender, age of disease onset, time to initiation of levodopa treatment and history of smoking.

RESULTS

Two patients were homozygous for the APOE ε2 allele, 7 had ε2/ε3, 1 had ε2/ε4, 130 had ε3/ε3, 12 had ε3/ε4 and 3 had ε4/ε4; LID appeared in 57.4% of the patients, appearing 4.1 ± 3.5 years after the initiation of levodopa treatment. The survival curve for LID was not affected by the APOE genotype (P = 0.34).

CONCLUSION

APOE polymorphisms were found not to be associated with either the occurrence or the time to development of LID.

ApoE and cholesterol in schizophrenia and bipolar disorder: comparison of grey and white matter and relation with APOE genotype

BACKGROUND

Apolipoprotein E (apoE) and cholesterol play a critical role in synapse and myelin maintenance and integrity and are thus appealing candidates in the pathogenesis of schizophrenia and bipolar disorder. To explore the role of these 2 molecules, we quantified cholesterol and apoE levels in prefrontal grey and white matter in patients with schizophrenia, bipolar disorder and healthy controls. Furthermore, we investigated the relations between apoE and cholesterol levels and the APOE genotype.

METHODS

We obtained dorsolateral prefrontal grey and white matter from the Stanley Medical Research Institute Brain Collection (schizophrenia n = 35, bipolar disorder n = 35 and controls n = 35). Cholesterol levels were quantified using high-pressure liquid chromatography, whereas apoE was measured by enzyme-linked immunosorbent assay.

RESULTS

We found no significant differences in cholesterol or apoE levels among the groups. ApoE levels were higher in grey matter than in white matter in all groups; conversely, levels of cholesterol were higher in white matter than in grey matter. We observed a significant inverse correlation between apoE and cholesterol levels in both grey and white matter. Furthermore, in grey matter, apoE levels were significantly higher in APOE ε2 carriers compared with APOE ε3 or APOE ε4 carriers, with cholesterol levels following the opposite trend.

LIMITATIONS

LIMITATIONS of our study include our inability to control for potential confounding variables and the small numbers of APOE ε2 and ε4 carriers in each group.

CONCLUSION

Although large amounts of cholesterol are present in white matter, apoE expression is limited. The APOE genotype may play a role in the regulation of both cholesterol and apoE levels in grey matter. The impact of APOE polymorphisms on lipid homeostasis in people with psychiatric disorders warrants further investigation.

PIN1 gene variants in Alzheimer's disease

BACKGROUND

Peptidyl-prolyl isomerase, NIMA-interacting 1 (PIN1) plays a significant role in the brain and is implicated in numerous cellular processes related to Alzheimer's disease (AD) and other neurodegenerative conditions. There are confounding results concerning PIN1 activity in AD brains. Also PIN1 genetic variation was inconsistently associated with AD risk.

METHODS

We performed analysis of coding and promoter regions of PIN1 in early- and late-onset AD and frontotemporal dementia (FTD) patients in comparison with healthy controls.

RESULTS

Analysis of eighteen PIN1 common polymorphisms and their haplotypes in EOAD, LOAD and FTD individuals in comparison with the control group did not reveal their contribution to disease risk.In six unrelated familial AD patients four novel PIN1 sequence variants were detected. c.58+64C>T substitution that was identified in three patients, was located in an alternative exon. In silico analysis suggested that this variant highly increases a potential affinity for a splicing factor and introduces two intronic splicing enhancers. In the peripheral leukocytes of one living patient carrying the variant, a 2.82 fold decrease in PIN1 expression was observed.

CONCLUSION

Our data does not support the role of PIN1 common polymorphisms as AD risk factor. However, we suggest that the identified rare sequence variants could be directly connected with AD pathology, influencing PIN1 splicing and/or expression.

Haptoglobin phenotype and apolipoprotein E polymorphism: relationship to posttraumatic seizures and neuropsychological functioning after traumatic brain injury

The relationship of genetic predisposition to reduced iron capacity and apolipoprotein E (APOE) to posttraumatic seizures (PTSs) and neuropsychological outcomes was investigated in patients with traumatic brain injuries from a prior valproate clinical study. Haptoglobin concentration/phenotype and APOE genotype were determined in 25 patients with PTSs and 26 control (no PTSs) subjects approximately 10 years after traumatic brain injury. Haptoglobin phenotype was also determined in previously collected frozen samples for 25 additional patients with PTSs and 32 no-PTS subjects. There was no relationship between haptoglobin phenotype or APOE genotype and occurrence of PTSs. APOE genotype was not related to neuropsychological outcome; however, when adjustments were made for differences in educational levels, APOE epsilon4 subjects did worse, especially on tests of verbal intellectual and verbal memory skills. In contrast to our hypothesis, those with haptoglobin 1-1 (high-affinity binder of hemoglobin) scored somewhat worse on Verbal IQ and Tapping D at 1 and 12 months after injury.

Apolipoprotein E allele 4 is not a sufficient or a necessary predictor of the development of Mild Cognitive Impairment

The presence of Mild Cognitive Impairment (MCI) and of an apolipoprotein E (apoE) varepsilon4 allele both predict the development of Alzheimer's disease. However, the extent to which this allele also predicts the development of MCI is unclear even though MCI is an early transitional stage in the development of Alzheimer's disease. The present study investigates the prevalence of the apoE varepsilon4 allele in incipient MCI. Participants were recruited from the population-based Leipzig Longitudinal Study of the Aged (LEILA75+). All subjects who were initially cognitively healthy, i.e. did not meet MCI criteria described by Petersen [Petersen RC. Mild cognitive impairment. J Intern Med 2004; 256(3): 183-94], and whose apoE status could be determined were followed-up. After 4.5 years, 15.5% of the cognitively healthy target population had developed MCI. The frequencies of the apoE varepsilon4 genotype did not differ between individuals with incipient MCI (12.9%) and individuals who remained cognitively healthy during the study (18.4%, p>0.5). Consequently, the apoE varepsilon4 genotype is not a necessary or sufficient risk factor for MCI. Further studies need to investigate the influence of the whole range of genetic and environmental risk factors on the course of Alzheimer's disease including the initial development of MCI and the later conversion to Alzheimer's disease.

ACE I/D polymorphism in Alzheimer’s disease

Angiotensin-converting enzyme (ACE) has been reported to show altered activity in patients with neurological diseases. The recent studies found that a 287 bp insertion/deletion (I/D) polymorphism of the ACE gene may be associated with susceptibility to Alzheimer’s disease (AD) but the results have been heterogenous between studies in Europe. In the present study we examined for the first time the association of ACE I/D polymorphism along with APOE genotype in 70 sporadic AD and 126 control subjects in Slovak Caucasians (Central Europe). An increased risk for AD was observed in subjects with at least one APOE*E4 allele (OR=3.99, 95% CI=1.97–8.08). No significant differences for the genotype distribution or the allele frequency were revealed comparing controls and patients for ACE gene. Gene-gene interaction analysis showed increase of the risk to develop AD in subjects carrying both the ACE DD genotype and the APOE*E4 allele (OR=10.32, 95% C.I. 2.67–39.81).

The rate of conversion of mild cognitive impairment to dementia: predictive role of depression

BACKGROUND

Mild cognitive impairment (MCI) is a condition referring to the persons with cognitive deficits measurable in some form or another, but not meeting criteria for dementia, and who have an increased risk of becoming demented.

OBJECTIVE

To establish the rate of progression to dementia in MCI, to investigate the risk of conversion for amnestic vs multiple-domains subtypes, and to identify the predictors of progression.

METHODS

MCI (n = 105) individuals enrolled in a longitudinal study received annual clinical and psychometric examinations for up to a mean of 3 years. The diagnosis of MCI according to Mayo Clinic Petersen's Criteria was conducted by a panel of specialists.

RESULTS

After 3 years of follow-up, 23 of 105 subjects with MCI were diagnosed with dementia. 40 showed cognitive decline not dementia, 34 were stable and showed no cognitive decline or improvement, while eight showed cognitive improvement.

CONCLUSIONS

We conclude that conversion rate from MCI to DSM-IIIR dementia was 21.9% over a period of 3 years. The occurrence of depressive symptoms may constitute a predictor for those who are more likely to progress to dementia. The risk of conversion to dementia was higher among the subjects with an evidence of impairment extending beyond memory than with those who suffered only from memory deficits, and the subjects who converted to dementia in this subtype had significantly higher baseline plasma total homocysteine levels than non-converters.

Sigma receptor type 1 gene variation in a group of Polish patients with Alzheimer's disease and mild cognitive impairment

The sigma-1 receptor (SIGMAR1) is a subtype of a nonopioid sigma receptor family and is implicated in numerous functions connected with Alzheimer's disease (AD). Two common genetic variants were identified in SIGMAR1: GC-241 -240TT and Q2P (A61C). It was suggested that the TT-C haplotype is a protective factor for AD. We decided to investigate a putative link between the variants of SIGMAR1 and AD in a group of Polish patients with late-onset AD, in patients with mild cognitive impairment, and in a control group. We observed no significant differences for the SIGMAR1 allele, genotype, haplotype, and diplotype distributions between the studied groups. Multivariate logistic regression analysis showed no interaction between the APOE4 and SIGMAR1 polymorphisms. Further studies using data from different populations are required to elucidate the effect of SIGMAR1 polymorphisms on AD.

Two novel presenilin 1 gene mutations connected with frontotemporal dementia-like clinical phenotype: Genetic and bioinformatic assessment

Mutations in the amyloid precursor protein (APP), presenilin 1 (PSEN1) and presenilin 2 (PSEN2) genes are associated with early-onset familial Alzheimer's disease (EOAD). There are several reports describing mutations in PSEN1 in cases with frontotemporal dementia (FTD). We identified two novel mutations in the PSEN1 gene: L226F and L424H. The first mutation was detected in a patient with a clinical diagnosis of FTD and a post-mortem diagnosis of AD. The second mutation is connected with a clinical phenotype of variant AD with strong FTD signs. In silico modeling revealed that the mutations, as well as mutations used for comparison (F177L and L424R), change the local structure, stability and/or properties of the transmembrane regions of the presenilin 1 protein (PS1). In contrast, a silent non-synonymous substitution F175S is eclipsed by external residues and has no influence on PS1 interfacial surface. We suggest that in silico analysis of PS1 substitutions can be used to characterize novel PSEN1 mutations, to discriminate between silent polymorphisms and a potential disease-causing mutation. We also propose that PSEN1 mutations should be considered in FTD patients with no MAPT mutations.

Polymorphism of Apolipoproteine E in Relation with Alzheimer and Vascular Dementia

1. The epsilon 4 allele of the apolipoprotein E gene increases the risk of late onset familial and sporadic Alzheimer disease. Relation of epsilon 4 allele of the apolipoprotein E gene to various types of dementia and the onset of dementia were analyzed in the present study. 2. The study comprised 139 patients (50 men and 89 women) with dementia, mean age 73.61 years (range 47-98). The diagnosis of dementia was made according to Diagnostic and Statistical Manual of Mental Disorders, and subtypes diagnoses were made according to NINCDS-ADRDA and NINDS-AIREN criteria. Minimental State Examination (MMSE) was used for the screening of dementia. Apolipoprotein E polymorphism was determined by the PCR-RFLP technique-polymerase chain reaction and subsequent digestion with specific restriction endonuclease. For statistical analyses chi-square test and the crude Gart s odds ratio (OR) and 95% confidence intervals (CI) were used. 3. From 139 dementia patients (MMSE < or =24 points) in 61 (45%) Alzheimer disease (AD) was present, in 44 patients (31%) vascular dementia (VD), and in 34 (24%) mixed dementia (MD) were revealed. In comparison with control group the presence of at least one ApoE-varepsilon4 allele was significantly higher only in the group with AD (p < 0.001), (OR=2.76; 95%: 1.42-5.36). The frequency of epsilon4 allele carriers was significantly overrepresented in AD group compared with VD (chi(2)=5.94; p=0.0148). Differences between AD and MD or VD and MD were not confirmed.

Association of depression with Alzheimer's disease and vascular dementia in an elderly Arab population of Wadi-Ara, Israel

OBJECTIVES

Because dementia and depression share common risk factors, we investigated risk factors for depression in Arab subjects with Alzheimer's disease (AD) and vascular dementia (VaD).

METHODS

In a cross-sectional population-based study, we conducted a door-to-door survey of all adults over age 60 in an Arab community of rural Israel. We conducted interviews, gave questionnaires, and collected DNA blood specimens for determination of ApoE genotype.

RESULTS

Of the 823 individuals in this naturalistic sample, 168 had dementia of Alzheimer's type (DAT) and 49 had VaD. Vascular risk factors, including the ApoE-epsilon4 allele, were more prevalent among VaD than DAT subjects. Depressive symptoms were present in 57% of DAT patients and 86% of VaD patients. Depressed DAT individuals had a greater history of ischemic cardiovascular or cerebrovascular (CV/CBV) disease than non-depressed DAT subjects, but depressed DAT subjects were less likely to have the ApoE-epsilon4 allele. Within the VaD group, there was no difference in the distribution of cardiovascular risk factors in individuals with and without depressive symptoms, and ApoE-epsilon4 was more prevalent among subjects with depressive symptoms.

CONCLUSIONS

Depressive symptomatology is prevalent among subjects with dementias in this Arab community. History of CV/CBV is associated with the presence of depressive symptoms in DAT. Further studies are needed to clarify the role of ApoE in depression onset in different ethnic groups with DAT.

Decreased beta-amyloid peptide42 in cerebrospinal fluid of patients with progressive supranuclear palsy and corticobasal degeneration

Several previous studies have identified biochemical markers for Alzheimer's disease (AD): cerebrospinal fluid (CSF)-beta-amyloid peptide42 (CSF-Abeta42), CSF-total tau protein (CSF-tau) and CSF-phosphorylated tau protein (CSF-ptau). Progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) as well as AD are diseases with tauopathies. CSF-Abeta42, CSF-tau, and CSF-ptau have not been rigorously investigated in PSP and CBD. In the present study, we assessed CSF-Abeta42, CSF-tau, and CSF-ptau as biochemical markers for PSP and CBD, compared with AD. The subjects consisted of 18 cases of PSP, 9 cases with CBD, 69 cases with AD, and 43 control subjects. Genotyping or phenotyping of apolipoprotein E (apoE) was also performed. CSF-Abeta42 levels were significantly decreased in patients with PSP and CBD as well as in AD patients. The ratio of CSF-ptau to CSF-Abeta42 provided high diagnostic accuracy to distinguish both PSP from AD, and CBD from AD. ApoE genotype/phenotype was not associated with CSF-Abeta42 levels in all groups. We concluded that CSF-Abeta42 levels are reduced in PSP and CBD as well as in AD.

Detection of ApoE E2, E3 and E4 alleles using MALDI-TOF mass spectrometry and the homogeneous mass-extend technology

Apolipoprotein (Apo) E is one of the five main types of blood lipoproteins (A–E). It is synthesized primarily in the liver and brain and helps in transporting lipids from one place to another as well as facilitates the clearing of dietary fats, such as triglycerides, from the blood. The ApoE gene exists in three different forms: E2, E3 and E4. E3 is considered to be the normal form. Variants of the ApoE gene have been associated with various diseases. Developing an assay for the genotyping of ApoE variants for use both in clinical and large cohort based association settings would be extremely valuable and would require the use of a platform that has high-throughput capabilities and is highly accurate. Here we describe an assay for the simultaneous genotyping of the ApoE variants in a single bi-plex reaction and a single well using the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry and the homogeneous mass-extend (hME) technology. The assay is robust, highly accurate and suitable for both clinical applications and for the genotyping of large disease cohorts. Moreover, the prevalence of ApoE variants in a cohort of Caucasians from the central Wisconsin area is outlined.

CYP46: A risk factor for Alzheimer's disease or a coincidence?

Excess cholesterol is removed from the brain via hydroxylation mediated by cholesterol 24S-hydroxylase (CYP46). Although serum and cerebrospinal fluid (CSF) concentrations of 24S-hydroxycholesterol are altered during the progress of Alzheimer's disease, studies carried out to date in different populations on the association of CYP46 gene polymorphisms and risk of AD have been inconclusive. In this report, we analyzed CYP46 polymorphisms in 215 Polish AD cases and 173 healthy individuals. A fragment of CYP46 intron 2 was amplified by PCR reaction and sequenced. We discovered a new single nucleotide substitution in CYP46 intron 2, but found no difference in particular genotype or allele frequencies between AD patients and controls. However, the GG genotype of the known rs754203 polymorphic site might be a risk factor for AD, especially in APOE varepsilon4 carriers. Interestingly, in AD patients the rs754203 G allele was more frequent in males than in females. However, considering the extreme divergence of results obtained by different authors, a clear connection between the CYP46 gene and AD is questionable.

High frequency of Fredrickson's phenotypes IV and IIb in Brazilians infected by human immunodeficiency virus

Background

Human immunodeficiency virus (HIV) infection is very prevalent in Brazil. HIV therapy has been recently associated with coronary heart disease (CHD). Dyslipidemia is a major risk factor for CHD that is frequently described in HIV positive patients, but very few studies have been conducted in Brazilian patients evaluating their lipid profiles.

Methods

In the present work, we evaluated the frequency and severity of dyslipidemia in 257 Brazilian HIV positive patients. Two hundred and thirty-eight (93%) were submitted to antiretroviral therapy (224 treated with protease inhibitors plus nucleoside reverse transcriptase inhibitors, 14 treated only with the latter, 12 naive and 7 had no records of treatment).

The average time on drug treatment with antiretroviral therapy was 20 months. None of the patients was under lipid lowering drugs. Cholesterol, triglyceride, phospholipid and free fatty acids were determined by enzymatic colorimetric methods. Lipoprotein profile was estimated by the Friedewald formula and Fredrickson's phenotyping was obtained by serum electrophoresis on agarose. Apolipoprotein B and AI and lipoprotein "a" were measured by nephelometry.

Results

The Fredrickson phenotypes were: type IIb (51%), IV (41%), IIa (7%). In addition one patient was type III and another type V. Thirty-three percent of all HIV+ patients presented serum cholesterol levels ≥ 200 mg/dL, 61% LDL-cholesterol ≥ 100 mg/dL, 65% HDL-cholesterol below 40 mg/dL, 46% triglycerides ≥ 150 mg/dL and 10% have all these parameters above the limits. Eighty-six percent of patients had cholesterol/HDL-cholesterol ratio ≥ 3.5, 22% increased lipoprotein "a", 79% increased free fatty acids and 9% increased phospholipids. The treatment with protease inhibitors plus nucleoside reverse transcriptase inhibitors increased the levels of cholesterol and triglycerides in these patients when compared with naïve patients. The HDL-cholesterol (p = 0.01) and apolipoprotein A1 (p = 0.02) levels were inversely correlated with the time of protease inhibitor therapy while total cholesterol levels had a trend to correlate with antiretroviral therapy (p = 0.09).

Conclusion

The highly varied and prevalent types of dyslipidemia found in Brazilian HIV positive patients on antiretroviral therapies indicate the urgent need for their early diagnosis, the identification of the risk factors for CHD and, when needed, the prompt intervention on their lifestyle and/or with drug treatment.

Brain area- and isoform-specific inhibition of synaptic plasticity by apoE4

The allele E4 of apolipoprotein E4 (apoE4), the most prevalent genetic risk factor of Alzheimer's disease (AD), inhibits the improvements in learning and memory which result from exposure of apoE transgenic mice to environmental stimulation (ES). In the present study, we investigated the extent to which these cognitive deficits are associated with distinct presynaptic, postsynaptic and axonal impairments and whether these effects are brain area-specific. Exposure to an enriched environment of young mice transgenic for human apoE3, which is the AD benign apoE allele, increased the levels of the presynaptic protein synaptophysin and of the dendritic marker MAP-2 in the hippocampus and entorhinal cortex, whereas the corresponding levels of these proteins in the apoE4 transgenic mice were unaffected by the enriched environment. In contrast, the levels of synaptophysin and MAP-2 in the motor cortex were elevated by environmental stimulation in both the apoE3 and the apoE4 transgenic mice. These findings show that apoE4 inhibits synaptic plasticity following environmental stimulation and that this effect is both isoform- and brain area-specific.

Age, apolipoprotein E4, and the risk of HIV dementia: the Hawaii Aging with HIV Cohort

There are discrepant findings regarding the risk of HIV-associated dementia (HAD) relating to apolipoprotein E4, suggesting other factors may modulate risk. Furthermore, evidence suggests a changing phenotype of HAD in the era of highly active antiretroviral therapy (HAART), prompting a need to determine if new disease markers have emerged. In this analysis, APOE genotype was determined for 182 participants enrolled in the Hawaii Aging with HIV Cohort. After controlling for age and diabetes status, an independent risk of HAD relating to E4 was seen in older participants [OR=2.898 (1.031-8.244)] but not in younger participants [OR=0.373 (0.054-1.581)]. Several proposed mechanisms may underlie this association. Consideration of non-traditional risk factors for HAD in older HIV patients may yield new markers of disease in the era of HAART.

Host genetic polymorphisms in human immunodeficiency virus-related neurologic disease

The objective of this study was to determine whether host genetic polymorphisms influence the risk of developing human immunodeficiency virus (HIV) encephalitis and vacuolar myelopathy. Allelic association studies were carried out with common polymorphisms in candidate genes that are postulated to play a role in the pathogenesis of HIV-related neurologic complications. The authors studied brains and spinal cords from 270 patients who died of acquired immunodeficiency syndrome (AIDS) from 1989 to 1996. All had complete gross and microscopic pathologic evaluations, and the presence of microglial nodules, multinucleated giant cells, myelin pallor, and vacuolar myelopathy was assessed by an experienced neuropathologist who was blinded to the genotype. DNA was extracted from frozen brain samples, and determination of the presence of the APOE4, TNF-2, IL-1B*2, ILIRN*2 polymorphisms was determined by polymerase chain reaction (PCR) and restricted fragment length polymorphism (RFLP) mapping. The authors did not detect a consistent association between inheritance of candidate polymorphic alleles and the pathologic findings of HIV encephalitis or vacuolar myelopathy. Allelic association studies with candidate genes are powerful techniques that have the potential to contribute to understanding the pathophysiology of HIV-related neurodegeneration. This preliminary study, although including a substantial number of patients, was not sufficiently powered to exclude a modest but clinically significant effects. Future studies will require much larger sample sizes and technical advances to allow screening at larger number of candidate loci.

The E318G substitution in PSEN1 gene is not connected with Alzheimer's disease in a large Polish cohort

Mutations in the presenilin 1 (PSEN1) gene are known to cause nearly 50% of early-onset, familial Alzheimer's disease (AD) cases. To determine whether E318G mutation is related causally to AD in the Polish population E318G mutation frequency was assessed using PCR-RFLP method in a total of 659 subjects: 256 AD patients, 210 healthy, age-matched control subjects, 100 Parkinson's disease patients and 93 centenarians. When the mutation frequencies were compared to healthy controls, no significant differences between the groups were found. It could be concluded that E318G mutation is not related causally to AD in the Polish population, either as a risk factor or a disease causing mutation.

Mutations in presenilin 1, presenilin 2 and amyloid precursor protein genes in patients with early-onset Alzheimer's disease in Poland

Mutations in three causative genes have been identified in patients with an autosomal-dominant form of early-onset Alzheimer's disease (EOAD). To determine the spectrum of mutations in a group consisting of 40 Polish patients with clinically diagnosed familial EOAD and 1 patient with mild cognitive impairment (MCI) and family history of AD, we performed a screening for mutations in the presenilin 1 (PSEN1), presenilin 2 (PSEN2) and amyloid precursor protein (APP) genes. Four previously recognized pathogenic mutations in PSEN1 gene (H163R, M139V) and APP gene (T714A, V715A), and three novel putative mutations in PSEN1 gene (P117R and I213F) and PSEN2 gene (Q228L) were identified. The 34 patients with no mutations detected were older than the patients with mutations. A frequency of APOE4 allele was higher in this group. Frequency of mutations is relatively low (17%), possibly due to used operational definition of a patient with familial EOAD (a patient having at least one relative with early-onset dementia). It could be concluded that screening for mutations in the three genes could be included in a diagnostic program directed at patients with a positive family history or age of onset before 55 years.

Apolipoprotein e4 decreases whereas apolipoprotein e3 increases the level of secreted amyloid precursor protein after closed head injury

Apolipoprotein E (apoE4) and head trauma are important genetic and environmental risk factors for Alzheimer's disease. Furthermore, apoE4 increases both the acute and chronic consequences of head trauma. The latter are associated with the deposition of amyloid-beta, which is particularly elevated in apoE4 subjects. The short-term effects of head injury are associated with transiently increased metabolism of amyloid precursor protein (APP) and its secreted fragment, APPs. In the present study, we examined the possibility that the acute, short-term pathological effects of apoE4 following head trauma and the corresponding neuroprotective effects of apoE3 are related to isoform-specific effects of apoE on APP metabolism. Accordingly, male transgenic mice expressing human apoE3 or apoE4 on a null mouse apoE background and apoE-deficient and control mice were subjected to closed head injury (CHI). The resulting effects on brain APP, and on its secreted products, APPs and secreted product of the alpha-cleavage of APP (APPsalpha) were then determined 24 h following injury. Immunoblotting revealed no significant differences between the basal APP, APPs and APPsalpha levels of the hippocampus or the cortex of the control and the apoE3 and ApoE4 transgenic mice. The apoE-deficient mice also had similar cortical basal levels of APP and its metabolites, whereas their corresponding basal hippocampal APP and APPs levels were lower than those of the other groups. CHI lowered the hipppocampal APPs and APPsalpha levels of the apoE4 transgenic mice, whereas those of the apoE3 transgenic mice and of the control and apoE-deficient mice were not affected by this insult. In contrast, CHI raised the cortical APP and APPs levels of the apoE3 transgenic mice but had no significant effect on those of the other mice groups. These animal model findings suggest that the acute, short-term pathological effects of apoE4 following CHI and the corresponding neuroprotective effects of apoE3 may be mediated by their opposing effects on the expression and cleavage of cortical and hippocampal APP. Similar isoform-specific interactions between apoE and APP may play a role in the acute, short-term effects of head trauma in humans.

Strong association between Saitohin gene polymorphism and tau haplotype in the Polish population

The saitohin (STH) gene is located in intron 9 of the tau protein gene. It has been postulated that the R allele of Q7R polymorphism at the Saitohin gene is over-represented in the homozygous state in sporadic Alzheimer's disease (AD). Tau protein was implicated in AD pathophysiology and the tau gene haplotype is probably connected with sporadic late-onset Parkinson's disease (PD). We analyzed the STH polymorphism and tau gene haplotype in 100 clinically diagnosed AD cases, 100 PD cases and 100 age-matched healthy controls. We found that the R allele of the STH gene is associated with the H2 haplotype of tau in all cases. Additionally we observed no correlation between R allele frequency and AD or PD.

ApoE4 impairs hippocampal plasticity isoform-specifically and blocks the environmental stimulation of synaptogenesis and memory

Alzheimer's disease (AD) is associated with genetic risk factors, of which the allele E4 of apolipoprotein E (apoE4) is the most prevalent, and is affected by environmental factors that include education early in life and socioeconomic background. The extent to which environmental factors affect the phenotypic expression of the AD genetic risk factors is not known. Here we show that the neuronal and cognitive stimulations, which are elicited by environmental enrichment at a young age, are markedly affected by the apoE genotype. Accordingly, exposure to an enriched environment of young mice transgenic for human apoE3, which is the benign AD apoE allele, resulted in improved learning and memory, whereas mice transgenic for human apoE4 were unaffected by the enriched environment and their learning and memory were similar to those of the nonenriched apoE3 transgenic mice. These cognitive effects were associated with higher hippocampal levels of the presynaptic protein synaptophysin and of NGF in apoE3 but not apoE4 transgenic mice. In contrast, cortical synaptophysin and NGF levels of the apoE3 and apoE4 transgenic mice were similarly elevated by environmental enrichment. These findings show that apoE4 impairs hippocampal plasticity and isoform-specifically blocks the environmental stimulation of synaptogenesis and memory. This provides a novel mechanism by which environmental factors can modulate the function and phenotypic expression of the apoE genotype.

Simultaneous analysis of five genetic risk factors in Polish patients with Alzheimer's disease

As Alzheimer's disease (AD) is a complex disease, we decided to estimate how previously reported genetic polymorphisms interact to increase the risk for the disease. Five candidate genes were chosen: apolipoprotein E (APOE), alpha 2-macroglobulin, cathepsin D, myeloperoxidase and nitric oxide synthase. Genotyping was performed in 100 cases of late-onset AD and 100 healthy controls. We found a highly significant difference in APOE epsilon 4 distribution between groups (P<0.005). However, no evidence of association for other studied loci was found. Cumulative analysis of five genetic polymorphisms was performed, but it also failed to reveal any synergistic effect of candidate genes greater than that caused by APOE itself. Our results suggest that the APOE epsilon 4 allele is the only known genetic risk factor for late-onset, sporadic AD.