脂联素、瘦素水平与阿尔茨海默病关系的系统评价

目的采用meta分析方法系统评价脂联素、瘦素与阿尔茨海默病(AD)之间的相关性。方法由两名研究者独立检索PubMed、《科学引文索引(SCI)》(Web of Science)、万方数据库、维普数据库(VIP)、中国期刊全文数据库(CNKI)、中国生物医学数据库(CBM)中脂联素、瘦素与AD的相关文献,检索时间为各数据库文献自收录开始至2019年1月。Meta分析采用Stata 14.0进行。结果脂联素相关文献纳入9篇文献,研究对象共2077例,其中AD患者558例,对照组1519例;瘦素相关文献纳入7篇文献,研究对象共539例,其中AD患者274例,对照组265例。Meta分析结果显示:(1)AD患者血浆平均脂联素水平(SMD=-0.79,95%CI:-1.94～-0.36,P=0.19)与对照组比较差异无统计学意义,Egger’s检验显示无发表偏倚(P=0.70),敏感性分析显示结果稳健。AD患者血清平均脂联素水平M (SMD=-0.94,95%CI:-2.08～-0.20,P=0.11)与对照组比较差异无统计学意义,Egger’s检验显示无发表偏倚(P=0.58),敏感性分析显示结果稳健。(2)AD患者血浆平均瘦素水平(SMD=0.34,95%CI:-1.36～-2.03,P=0.70)与对照组比较差异无统计学意义。AD患者血清平均瘦素水平(SMD=-0.48,95%CI:-0.66～-0.30,P0.00001)与对照组比较差异有统计学意义,Egger’s检验显示无发表偏倚(P=0.11),敏感性分析显示结果稳健。结论血浆中脂联素、瘦素水平以及血清中脂联素水平与AD无显著相关性。血清中瘦素水平有可能作为预测AD的生物标志物。     

3D打印导航模板与计算机导航系统在辅助椎弓根螺钉置入准确性与安全性的Meta分析

目的 系统评价3D打印导航模板与计算机导航系统在椎弓根螺钉置入术中的临床疗效与安全性。方法 系统检索中国知网、万方数据库和维普网、PubMed、Web of Science及The Cochrane Library数据库中有关3D打印导航模板与计算机导航系统在椎弓根螺钉置入术中的临床对照试验文献,检索时间范围为建库至2022-11,由2名研究者分别根据纳入、排除标准进行文献筛选,并进一步对数据进行提取和质量评价,使用RevMan 5.3软件对所提取出的数据进行分析。结果 共纳入7篇文献,包含3篇随机对照试验,其质量评价均为中等偏倚风险,4个回顾性研究,根据NOS量表进行评分,结果均>7分,为高质量文献;所纳入的文献共包含346例患者,其中3D打印组178例,计算机导航组168例。Meta分析显示,3D打印组和计算机导航组在手术时间(MD=-41.10,95%CI:-74.54～-7.67,P<0.05)、平均置钉(MD=-4.92,95%CI:-8.50～-1.35,P<0.05)和置钉准确率(RR=1.09,95%CI:1.04～1.15,P=0.001)上差异均有...     

幽门螺杆菌感染与阿尔茨海默病相关性的Meta分析

目的系统评价幽门螺杆菌（H.pylori）感染与阿尔茨海默病（AD）发生的相关性。方法 计算机检索PubMed、Embase、Cochrane Library、Web of Science、中国知网、万方数据库、维普数据库、中国生物医学文献服务系统数据库中关于H.pylori感染与AD之间关联的病例对照研究和队列研究，检索时限为2000年1月至2022年11月。2名研究者对文献进行筛选、提取资料和质量评价。采用RevMan 5.3软件进行Meta分析。结果 共纳入15项研究，包括9项病例对照研究（n=1 404）,6项队列研究（n=7 893）。Meta分析结果显示，AD组的H.pylori感染率高于对照组（OR=1.58,95%CI:1.21～2.06,P<0.05），血清中的H.pylori IgG抗体含量高于对照组（MD=6.14,95%CI:2.99～9.29,P<0.01），简易精神状态检査（MMSE）评分低于对照组（MD=-9.89,95%CI:-14.04～-5.74,P<0.01）;H.pylori阳性组的AD发生率高于H.pylori阴性组（RR=1...     

多发性硬化患者抗EB病毒抗体阳性检出率的Meta分析

目的 通过Meta分析探讨多发性硬化(MS)患者体内抗EB病毒(EBV)抗体阳性率。方法 检索对MS病例与对照血清中抗EBV抗体进行检测的随机对照试验(RCT),并通过Meta分析探索各种抗EBV抗体与MS之间的关系。计算机检索中国期刊全文数据库(CNKI)、万方科技期刊全文数据库、PubMed、EMbase和维普中文科技期刊全文数据库(VIP),检索时限均从建库至2021年12月。两名研究者严格根据制定的纳入及排除标准独立进行文献筛选并提取基本资料,依据修改后的纽卡斯尔-渥太华量表(NOS)工具评价文献质量。采用Rev Man 5.3软件合并计算所有纳入文献中的每一种抗EBV抗体血清阳性率的OR,并进行敏感性分析和亚组分析。以Egger检验评价发表偏倚。结果 共纳入35项研究。MS患者EBV衣壳抗原抗体(EBV-VCA)IgG/IgM、EBV核心抗原抗体(EBNA)IgG血清阳性率明显高于对照者,效应量指标总体OR值及其95%CI分别为：EBV-VCA IgM(OR=3.44,95%CI:1.93～6.13)、EBV-VCA IgG(OR=4.79,95%CI:2.82～8.15)、...     

双相障碍与血清尿酸水平关系的Meta分析

目的:探讨双相障碍与血清尿酸水平的关系。方法:应用计算机检索Cochrane数据库、PubMed数据库、Embase数据库、中国期刊全文数据库(CNKI)、万方数据库和维普数据库。检索时间为建库至2019年3月,搜索双相障碍与血清尿酸关系的对照研究。采用Review manager5.3软件进行Meta分析。结果:共纳入13篇中英文文献,其中双相障碍患者组1 344例,1 931名正常对照组。Meta分析显示双相障碍患者组血清尿酸水平高于正常对照组[SMD=0.84(0.61,1.08),P 0.00001]。根据亚组分析结果,双相障碍不同临床相患者的血清尿酸高于正常对照组(P 0.00001)。不同种族双相障碍患者血清尿酸高于正常对照组(P 0.00001)。根据t检验分析结果,躁狂发作组血清尿酸高于抑郁发作组。华人组双相障碍患者血清尿酸高于非华人组。结论:血尿酸水平升高与双相障碍相关。结论需进一步大样本研究证实。     

丙戊酸单药治疗与癫患者血浆同型半胱氨酸水平间关系的Meta分析

目的分析癫患者血浆同型半胱氨酸水平变化与丙戊酸单药治疗间的关系。方法选择epilepsy、valproate、homocysteine和epilep*为检索词,计算机检索1990年1月-2013年8月美国国立医学图书馆、科学引文索引数据库、荷兰医学文摘等数据库,获得丙戊酸单药治疗与癫患者血浆同型半胱氨酸水平间关系的相关英文文献,均为丙戊酸单药治疗的癫患者与正常对照受试者血浆同型半胱氨酸水平比较的病例-对照临床研究。通过Newcastle-Ottawa量表独立进行文献质量评价和数据提取,Stata 12.0统计软件行Meta分析。结果共纳入符合条件的英文文献8篇,包括266例行丙戊酸单药治疗的癫患者和489例正常对照受试者,所有纳入文献质量评分均6分。Meta分析显示,丙戊酸单药治疗组患者血浆同型半胱氨酸水平显著高于正常对照组[标准化均数差(SMD)=0.620,95%CI:0.320~0.920;P=0.000];经异质性检验存在显著异质性(I2=65.600%,P=0.005),根据不同地区和受试者年龄差异行进一步亚组分析,结果显示西亚组癫患者异质性风险(I2=47.400%,P=0.107)较整体(I2=65.600%,P=0.005)降低。采用敏感性分析评价Meta分析之稳定性,当任何一项研究被剔除后,相应的SMD值均不发生变化,表明分析结果稳定性良好。结论丙戊酸单药治疗可显著增加癫患者血浆同型半胱氨酸水平,后者是否受种族因素的影响尚待进一步研究。     

西洛他唑治疗动脉瘤性蛛网膜下腔出血后脑血管痉挛的Meta分析

目的系统评价西洛他唑治疗动脉瘤性蛛网膜下腔出血后脑血管痉挛的有效性以及安全性。方法检索PubMed、Cochrane Library、EMBASE、中国生物医学文献、维普及万方数据库,检索时间从建库至2018年09月,收集西洛他唑治疗动脉瘤性患者的临床对照试验。由2名研究者严格制定纳入标准、筛选文献,提取资料,评价质量并用Rev Man5. 3软件进行Meta分析。结果最终纳入临床研究6项,共618例动脉瘤性蛛网膜下腔出血患者。Meta分析结果显示西洛他唑在以下方面优于常规治疗,且差异有统计学意义(P 0. 05),西洛他唑能降低症状性脑血管痉挛(OR=0. 31,95%CI:0. 21-0. 48),重度脑血管痉挛(OR=0. 47,95%CI:0. 31-0. 69),迟发性脑梗塞(OR=0. 32,95%CI:0. 20-0. 52)的发生率,且能够改善患者预后(OR=2. 65,95%CI:1. 66-4. 21)。结论西洛他唑可以降低动脉瘤性蛛网膜下腔出血所致脑血管痉挛的发生率,并对改善预后有一定帮助。     

微信干预对社区精神分裂症患者服药依从性、精神病性症状及复发率影响的Meta分析

目的系统评价微信干预对社区精神分裂症患者服药依从性、精神病性症状及复发率的影响。方法计算机检索PubMed、Cochrane Library、CBM、中国知网、万方和维普数据库,搜集有关微信干预对社区精神分裂症患者影响的随机对照研究,检索时限均为2011年1月1日-2020年11月1日。由2名研究者独立筛选文献、提取数据并评价纳入研究的偏倚风险后,采用Stata 12.0进行Meta分析。结果共检索到381篇文献,最终纳入10项随机对照研究,共1251例患者,其中微信干预组641例,常规健康教育组610例。Meta分析结果显示,相对于常规健康教育组,微信干预组服药依从性(OR=3.05,95%CI:1.98~4.69,P<0.01)更高,PANSS评分(SMD=-1.05,95%CI:-1.46~-0.64,P<0.01)和复发率(OR=0.34,95%CI:0.24~0.48,P<0.01)更低。结论基于微信平台的互动干预方式可能有助于提高社区精神分裂症患者服药依从性、改善精神病性症状和降低复发率。     

中国精神分裂症患者认知电位P300研究的系统评价

目的 评价中国精神分裂症患者认知电位P300的特点及影响因素.方法 制定原始文献的纳入标准、排除标准及检索策略,检索PubMed、EMBase、Web of knowledge、Cochrane Library、PsycINFO、中国期刊全文数据库、万方数据库、维普中文科技期刊数据库及中国生物医学文献光盘数据库等.应用加强观察性流行病学研究报告的质量(STROBE)为参照评价标准评价文献质量.采用Stata 11软件对满足纳入标准的研究资料进行Meta分析.结果 共有38篇文献符合纳入标准进行Meta分析.随机效应合并分析显示,精神分裂症患者P300波幅低于正常对照组[总效应Z=7.98,合并SMD=-0.937,95％CI( -1.167～ -0.706),P＜0.000 01],潜伏期大于正常对照组[总效应Z＝7.69,合并SMD=0.969,95％CI(0.722～1.215),P＜0.000 01],差异均有统计学意义.敏感性分析结果显示,两组的合并效应结果稳定性均较好.Meta回归显示波幅与检验仪器(P＝0.036)有关,而潜伏期可能与是否用药(P＝0.099)有关.结论 精神分裂症患者存在认知电位P300异常,表现为波幅降低和潜伏期延长,两个指标的稳定性均较好.     

音乐疗法治疗卒中后抑郁的系统评价

目的:系统评价音乐疗法治疗卒中后抑郁的疗效和安全性。方法:计算机检索Pub Med、EMBASE、Cochrane Library、中国生物医学文献数据库(CBM)、中国期刊全文数据库(CNKI)、维普数据库(VIP)、万方医学网结合手工检索各数据库从建库至2018年1月纳入的音乐疗法联合常规疗法与常规疗法比较治疗卒中后抑郁(PSD)的随机对照试验(RCT)文献;参照纳入排除标准筛选文献,使用改良的Jadad量表评价纳入文献质量,提取治疗前后汉密尔顿抑郁量表(HAMD)评分及不良反应数据,以HAMD评分变化的均数差(MD)进行疗效评价,采用Rev Man 5. 3软件进行Meta分析。结果:共纳入16个RCT共1 431例患者,均为开放性非安慰剂对照试验。Meta分析结果显示,音乐治疗组患者抑郁症状改善优于对照组(MD=4. 14,95%CI:1. 66～6. 62,P 0. 01)。结论:音乐疗法联合常规疗法对降低PSD患者的HAMD评分优于常规治疗。     

No association between hypertension and risk for Alzheimer's disease: a meta-analysis of longitudinal studies

This study examined the association between hypertension and AD by using a quantitative meta-analysis of longitudinal studies. EMBASE and MEDLINE were searched for articles published up to February 2011. All studies that examined the association of hypertension or antihypertensive medication use with the onset of AD were included. Pooled relative risks (RR) were calculated using fixed and random effects models. Twelve studies met our inclusion criteria for this meta-analysis. All subjects were without dementia at baseline. Among them, 9 studies compared the incidence of AD between subjects with (7,270) and without (8,022) hypertension. The quantitative meta-analysis showed that there was no significant difference in incidence of AD (RR: 1.02, 95% confidence interval (CI): 0.91-1.14) between subjects with and without hypertension. Seven studies compared the incidence of AD between subjects with (8,703) and without (13,041) antihypertensive medication use. The quantitative meta-analysis showed that there was no significant difference in incidence of AD (RR: 0.90, 95% CI: 0.79-1.03) between subjects with and without antihypertensive medication use. The quantitative meta-analysis showed that neither hypertension nor antihypertensive medication use was associated with risk for incident AD.     

DJ-1基因多态性与帕金森病易感性的Meta分析

目的评价DJ-1基因多态性与帕金森病(PD)易感性的关系。方法检索知网、万方、Web of Science、Pub Med、EMBASE和Cochrane数据库,检索时间为2001年01月01日至2017年01月01日。确定文献纳入排除标准,并采用Newcastle-Ottawa Scale(NOS)进行质量评估,提取高质量文献的有用部分,使用stata12.0软件进行统计分析。结果共纳入12篇文献,收集到2895组病例和2817组对照,Meta分析结果显示,在帕金森病患者中,DJ-1基因g.168_185del缺失突变(OR=1.26,95%CI:1.06~1.50,P0.05)和c.G293A点突变(OR=2.74,95%CI:1.22~6.16,P0.05)均为PD的危险因素。在g.168_185del与PD相关性研究的亚组分析中,发现非中国人群g.168_185del多态性也是PD的危险因素(OR=1.41,95%CI:1.14~1.73,P0.05),但在中国人群中未发现其相关性(OR=0.98,95%CI:0.72~1.34,P0.05)。c.G293A与PD相关性病例对照研究中均为非中国人群,故未进行亚组分析。结论DJ-1基因g.168_185 del缺失突变和c.G293A点突变是PD的易感因素,但本Meta分析未发现DJ-1基因g.168_185 del缺失突变和c.G293A点突变与中国人群PD具有相关性。     

Interleukin-1A ?889C/T polymorphism and risk of Alzheimer’s disease: a meta-analysis based on 32 case–control studies

The Interleukin-1A (IL-1A) -889C/T polymorphism has been reported to be associated with Alzheimer's disease (AD) susceptibility, but the results of these previous studies have been inconsistent. The aim of this study was to explore whether the IL-1A -889C/T polymorphism confers susceptibility to AD. All studies published up to July 2011 on the association between the IL-1A -889C/T polymorphism and AD risk were identified by searching electronic databases PubMed, Embase and Alzgene. The association between the IL-1A -889C/T polymorphism and AD risk was assessed by odds ratios (ORs) together with their 95% confidence intervals (CIs). A total of 32 case-control studies including 7,046 AD cases and 7,534 controls were eventually identified. Overall, positive associations of the IL-1A -889C/T polymorphism with AD risk were found in allele comparison T versus C (OR = 1.019, 95% CI= 1.027-1.198), recessive model TT versus CT + CC (OR = 1.278, 95% CI = 1.073-1.522) and dominant model TT + CT versus CC (OR = 1.102, 95% CI = 1.013-1.200). In subgroup analysis stratified by ethnicity, significant associations were demonstrated in Caucasians but not in Asians. In subgroup analysis according to the age of onset, no significant association was detected. The present meta-analysis suggests that the IL-1A is a candidate gene for AD susceptibility. The IL-1A -889C/T889C/T polymorphism may be a risk factor for AD in Caucasians. Further investigations taking the APOE ε4 status and other confirmed genetic factors and potential gene-gene and gene-environmental interactions into consideration for this polymorphism should be conducted.     

Plasma and cerebrospinal fluid levels of amyloid beta proteins 1-40 and 1-42 in Alzheimer disease

BACKGROUND: In brains with AD, Abeta is a major component of diffuse plaques. Previous reports showed that CSF Abeta42 levels were lower in patients with AD than in controls. Although studies showed higher plasma Abeta42 levels in familial AD, a recent report has indicated that plasma Abeta42 levels were similar in a sporadic AD group and controls. However, no information is published on plasma Abeta40 and Abeta42 levels in relation to Apo E genotype or severity of dementia in sporadic AD. OBJECTIVE: To examine plasma and cerebrospinal fluid (CSF) levels of amyloid beta protein 1-40 (Abeta40) and 1-42 (Abeta42) levels in patients with probable Alzheimer disease (AD) and elderly nondemented control subjects in relation to the apolipoprotein E (Apo E) genotype and dementia severity. SETTING: Two university medical centers. PATIENTS AND METHODS: Levels of Abeta40 and Abeta42 were measured in plasma from 78 patients with AD and 61 controls and in CSF from 36 patients with AD and 29 controls by means of a sandwich enzyme-linked immunosorbent assay. RESULTS: Mean plasma Abeta40 levels were higher in the AD group than in controls (P = .005), but there was substantial overlap; Abeta42 levels were similar between the groups. Levels of Abeta40 and Abeta42 showed no association with sex or Mini-Mental State Examination scores. There was a significant relationship between age and Abeta40 level in controls but not in the AD group. Levels of Abeta40 were higher in patients with AD with the Apo E epsilon4 allele than in controls (P<.01). Cerebrospinal fluid Abeta40 levels were similar in the AD group and controls. However, Abeta42 levels were lower in the AD group than in controls (P<.001). The levels showed no association with severity of dementia. CONCLUSIONS: Although mean plasma Abeta40 levels are elevated in sporadic AD and influenced by Apo E genotype, measurement of plasma Abeta40 levels is not useful to support the clinical diagnosis of AD. Lower levels of CSF Abeta42 in the AD group are consistent with previous studies.     

Association of the NQO1 C609T polymorphism with Alzheimer's disease in Chinese populations: a meta-analysis

Several molecular genetics studies have investigated the association of NQO1 C609T polymorphism with Alzheimer's disease (AD) susceptibility in Chinese populations; however, the findings are inconclusive. To investigate the association, we performed the present meta-analysis of 5 case-control studies (including 735 AD cases and 828 controls). We searched literature from PubMed, Embase, HuGNet and CNKI databases for eligible articles that evaluated the association between NQO1 C609T polymorphism and AD risk. We used odds ratios (ORs) with 95% confidence intervals (CIs) to evaluate the strength of the association. Overall, C609T polymorphism was significantly associated with an increased AD risk (homozygote: OR = 1.87, 95% CI = 1.39–2.51, P = 0.000; heterozygote: OR = 1.93, 95% CI = 1.22–3.06, P = 0.019; dominant: OR = 1.97, 95% CI = 1.25–3.12, P = 0.004). When stratified by source of control, significant results were observed in subjects of population-based (PB), whereas no increased risk was observed among the hospital-based (HB). When stratified by APOE?4 carrier status, no effect of the NQO1 C609T polymorphism was seen in subjects of APOE?4 carriers and APOE?4 non-carriers. In conclusion, our results showed that NQO1 C609T polymorphism increases the risk of AD in Chinese populations. Larger studies with different ethnic populations are required to validate our findings.     

ABCA2 is a strong genetic risk factor for early-onset Alzheimer's disease

Recent epidemiological, biological and genetic data indicate a relationship between cholesterol and Alzheimer's disease (AD) including the association of polymorphisms of ABCA1 (a gene that is known to participate in cholesterol and phospholipid transport) with AD prevalence. Based on these data, we postulated that genetic variation in the related and brain-specific ABCA2 gene leads to increase risk of AD. A large case-control study was conducted where the sample was randomly divided into a hypothesis-testing sample (230 cases/286 controls) and a validation sample (210 cases/233 controls). Among the 45 SNPs we tested, one synonymous SNP (rs908832) was found significantly associated with AD in both samples. Additional analyses performed on the whole sample showed a very strong association between this marker and early-onset AD (OR = 3.82, 95% C.I. = [2.00 - 7.30], P = 5 x 10(-5)). Further research is needed to understand the functional role of this polymorphism. However, together with the reported associations of AD with APOE, CYP46A1 and ABCA1, the present result adds a very significant support for the role of cholesterol and phospholipid homeostasis in AD and a rationale for testing novel cholesterol homeostasis-related therapeutic strategies in AD.     

Tracking cognitive decline in Alzheimer's disease using the mini-mental state examination: a meta-analysis

OBJECTIVES: To estimate the annual rate of change scores (ARC) on the Mini-Mental State Examination (MMSE) in Alzheimer's disease (AD) and to identify study or population characteristics that may affect the ARC estimation. METHODS: MEDLINE was searched for articles published from January 1981 to November 1997 using the following keywords: AD and longitudinal study or prognosis or cognitive decline. The bibliographies of review articles and relevant papers were searched for additional references. All retrieved articles were screened to meet the following inclusion criteria: (a) original study; (b) addressed cognitive decline or prognosis or course of AD; (c) published in English; (d) study population included AD patients with ascertainable sample size; (e) used either clinical or pathological diagnostic criteria; (f) longitudinal study design; and (g) used the MMSE as one of the outcome measures. Data were systematically abstracted from the included studies, and a random effects regression model was employed to synthesize relevant data across studies and to evaluate the effects of study methodology on ARC estimation and its effect size. RESULTS: Of the 439 studies screened, 43 met all the inclusion criteria. After 6 studies with inadequate or overlapping data were excluded, 37 studies involving 3,492 AD patients followed over an average of 2 years were included in the meta-analysis. The pooled estimate of ARC was 3.3 (95% confidence interval [CI]: 2.9-3.7). The observed variability in ARC across studies could not be explained with the covariates we studied, whereas part of the variability in the effect size of ARC could be explained by the minimum MMSE score at entry and number of assessments. CONCLUSIONS: A pooled average estimate of ARC in AD patients was 3.3 points (95% CI: 2.9-3.7) on the MMSE. Significant heterogeneity of ARC estimates existed across the studies and cannot be explained by the study or population characteristics investigated. Effect size of ARC was related to the initial MMSE score of the study population and the number of assessments.     

Association between interleukin-10 polymorphisms and Alzheimer's disease: a systematic review and meta-analysis

It has been hypothesized that polymorphisms of interleukin (IL)-10 genes affect the risk of developing late onset Alzheimer's disease (AD). However, results of different studies are often inconsistent. Our aim was to investigate by meta-analysis the association of the common polymorphisms comprehensively defining the genetic variability of the IL-10 gene with AD risk. Fifteen studies investigating the association between IL-10 polymorphisms (-1082, -819, -592) and AD were found and analyzed. The model-free approach was applied to meta-analyze these case-control genetic association studies. Available data suggested an association between -1082 polymorphism and AD risk with a marginal statistical significance (GG versus AG/AA: pooled odds ratio [OR]: 0.82, 95% confidence interval CI: 0.65-1.02) and evidence of a moderate degree of between-study heterogeneity (χ2 = 27.13, d.f. = 13, p = 0.01, I2 = 52%). For the -819 and -592 polymorphisms, we did not find an association with AD, but significant between-study heterogeneity made genotype data pooling unacceptable. Analysis by IL-10 haplotype showed that the -1082G/-819C/-592C haplotype is associated with a lower risk of AD, although with a marginal statistical significance, probably due to the low number of studies included (GCC versus other genotypes: OR: 0.61, 95% CI: 0.32-1.15; I2: 85%). Current findings suggest a possible association between -1082 A > G polymorphism and the risk of developing AD; this effect is more evident in the oldest patients. The high degree of between-study heterogeneity, due to several underpowered studies and to other methodological problems of individual studies underlies the need for further methodologically adequate studies.     

Tumor diagnosis preceding Alzheimer's disease onset: is there a link between cancer and Alzheimer's disease?

Studies reporting an inverse association between Alzheimer's disease (AD) and cancer are scant. Available data are mostly based on ancillary findings of mortality data or obtained from studies evaluating frequency of neoplasms in AD patients independently if they occurred before or after AD. Moreover, some studies estimated frequencies of neoplasms in demented individuals, who were not necessarily AD patients. We estimated frequency of tumors preceding the onset of AD in AD patients and compared it to that of age- and gender-matched AD-free individuals. Occurrence of tumors preceding AD onset was assessed through a semi-structured questionnaire. Tumors were categorized as benign, malignant, or of uncertain classification and as endocrine-related or not. Odds ratios (OR), used as measure of the association between the two diseases, were adjusted for tumor categories and known risk factors for AD and tumors. We included 126 AD patients and 252 matched controls. Tumor frequency before AD onset was 18.2% among cases and 24.2% among controls. There was a suggestive trend of an overall inverse association between the two diseases (adjusted OR 0.6; 95% CI 0.4-1.1; p = 0.11). Risk for neoplasms was significantly reduced only for women (adjusted OR, 0.5; 95% CI 0.3-0.9; p = 0.03) and for endocrine related tumors (adjusted OR, 0.5; 95% CI 0.2-1; p = 0.04). Our study confirms the inverse association reported in previous epidemiological studies. Though our findings might be explained by processes playing an opposite role in tumors development and neurodegeneration, they are also suggestive for a possible role of estrogen.